MATERIAŁY DYDAKTYCZNE DO PRZEDMIOTU INTRODUCTION TO GEODESYwisge-moodle.tu.kielce.pl/file.php/1/Introduction_to_Geodesy.pdf · and Isaraeli’s commercial system EROS. All of them

Projekt ,,Politechnika Świętokrzyska – uczelnia na miarę XXI w.’’ Program Operacyjny Kapitał Ludzki Priorytet IV Działanie 4.1, Poddziałanie 4.1.1

na podstawie umowy z Ministerstwem Nauki i Szkolnictwa Wyższego UDA – POKL.04.01.01-00-381/10-00

Projekt współfinansowany ze środków Unii Europejskiej w ramach Europejskiego Funduszu Społecznego

Biuro Projektu al. Tysiąclecia Państwa Polskiego 7 25-314 Kielce

tel. 41-34-24-209, e-mail: [email protected]

MATERIAŁY DYDAKTYCZNE DO PRZEDMIOTU

INTRODUCTION TO GEODESY

Wydział Budownictwa i Inżynierii Środowiska

Opracował Ludwik Śliwa



Projekt współfinansowany ze środków Unii Europejskiej w ramach Europejskiego Funduszu Społecznego

Biuro Projektu al. Tysiąclecia Państwa Polskiego 7 25-314 Kielce


Biuro Projektu al. Tysiąclecia Państwa Polskiego 7, 25-314 Kielce




L1 - What is Geodesy?

Geodesy belongs to the family of so called “Geosciences”, or a group of the scienc-

es dealing with our planet {Geo (from Greek language) = Earth}; similar to Geophysics,

Geology, Geography, Geomorphology, etc. For centuries the people have been trying to

understand our planet: its size,shape, and the gravity field, the landscapes and their evolu-

tion. The art and science concerned with the study of the Earth’s size , shape, orientation,

and the variations of these quantities over the time is called Geodesy. Geodesy provides

the data as the result of the surveys [measurements]. Their analysis and proper interpreta-

tion belongs usually to specialists in related areas. Such as, planetary sciences, geophysics,

oceanography, meteorology, GIS, or land planning & development. Besides human’s curi-

osity, adavances in Geodesy were driven by many practical applications, such as the nav-

igation, or surveying and mapping, to mention a few. Naturally, the concepts & under-

standing of our planet have been changing and modified accordingly over the time. From

Aristoteles’s (384-322 B.P.) concept of gravity, Ptolemy’s (305-282 B.P.) theory of the

Sun evolving around the Earth [which wasn’t challenged for almost 2 000 years (!)], to

Copernicus theory of the Earth evolving around the Sun, to Newton’s theory of classical

mechanics, and Einstein’s theory of relativity. There were many “milestones” on this path

. A few of them are listed below: determination of the size of the Earth by Eratostenes (ca

276 -194 B. P.) [with the error margin of 7 %], discovery of telescope by Galileo (1564-

1642), introduction of the rectangular coordinate system by Descartes (1596-1650) discov-

ery of the gravity field of the Earth [and other planets], formulation of the law of the plane-

tary motion by Johannes Kepler (1571-1630) [with contribution of Tycho de Brache

(1546-1601), who collected the observational data used by Kepler], introduction of the

concept of triangulation [or, another words: covering the countries by the sets of triangles

for the purposes of surveying & mapping] by Snellius (1580-1626), Mercator’s (1512-

1594) contribution to navigation & cartography (in 1569), contribution of mathematicians

such as Gauss (1777-1855) and Lagrange (1736-1813) to analitycal treatment of observa-

tional data, Wegener’s theory of plates tectonic motion, or launching the first artificial

Earth’s satellite [Sputnik] by former Soviet Union in 1957 [which initialized the so called

“space era”]. Human’s curiosity hasn’t changed much. What changed over the centuries is

the precision of carrying out the observation, the technics of data acquisition and the

amount of the acquired data. They usually confirm, or reject the mathematical models,

which are formulated to support the postulated theory. Small, yet detectable changes are

significant in Geodesy. Mainly, because these are associated with problems of great im-

portance, such as plate tectonic movements [and the earthquakes, which usually are asso-

ciated with them], ice caps melting and [as the consequence] the sea level rise, land sub-

sidence due to depletion of the natural resources [such as oil, gas, or other minerals], or

rate of precipitation and variations in ground water levels. All of them have a significant

impact on the society. The 20-th century was dominated by the type of measurements per-

formed mostly from the surface of the Earth. The advancements in electronic, sensors and

computer science had an impact on development of modern equipment and geodetic survey

techniques. They contributed to simplification and precision of the surveys and shortening

the time of the measurements performed in the field. They also facilitated the analysis and

interpretation of the data. But, although the types of surveys performed from the surface

of the Earth will not be eliminated altogether, in 21-th century the type of geodetic meas-

urements obtained mostly from space will prevail [“Satellite Geodesy”]; eventually with





conjunction [combination] with the surveys performed on the Earth.The new term: Space

Geodesy was coined by the late eighties of 20-th century. It covers the whole spectrum of

geodetic surveys , which relay on precise distance or phase/phase differences measure-

ments transmitted or reflected from extraterrestrial objects. Examples of which are: qua-

sars, the Moon, or artificial satellites. At the beginning of the space geodetic measurements

the accuracy levels were within the range of several centimeters.The examples of these

types of geodetic measurements are: Very Long Baseline Interferometry {VLBI], Lunar

Laser Ranging {LLR}, Synthetic Aperture Radar {SAR} or early LANDSAT missions.

The tremendeous advantage of using these types of geodetic measurements was, that it

covered the entire globe, without the necessity of direct access to vast, remote, hard to

access, or hazardeous areas. Such as the ridges of the mountains, deserts, jungles, earth-

quake zones, cones of the vulcanoes or flooded areas.Another one is, that geodetic space

techniques usually do not require the direct line of sight (LOS) between the measurement

points, as was the case with triangulation, trilateration or levelling. It might be interesting

to mention, that the uplift in Fennoscandia and the confirmation of the plate tectonic mo-

tions was due to [among others] direct geodetic observations. However, due to improving

space geodetic technologies and refining the methods of data treatment [detection and re-

moval of blunders, sofisticated methods of data analysis and displays], the accuracy in-

creased to subcentimeter levels. Small movements of the Earth’s solid and fluid surface

can be detected nowadays with space geodetic observations. The range of applications is

not limited to Solid Earth (SE) only, examples of which are: detection of earthquake and

magma –induced crustal deformation on the surface. But its also extended to Oceanogra-

phy and Hydrology {i.e Bathymetry,variations in Sea Surface Topography (SST), changes

in the ground water levels} or Atmospheric Sciences [among others they contribute to im-

provements in the weather prediction]. Generally, the space based geodetic observations

can be subdivided into five basic techniques (EOS): positioning, altimetry, interferometric

synthetic aperture radar (InSAR) and gravity [although gravity observations can be per-

formed on the surface of the Earth as well]. GNSS stands for Global Navigation Satellite

Systems. It encompasses the US Navy’s Global Positioning System (GPS), Russia’s Glob-

alnaya Navigatsionnaya Sputnikova Sistema (GLONASS) and European’s Galileo. Alt-

hough the first two missions were originally designed and developed for the military and

navigation purposes, they became very useful in Geodesy as well. Especially for precise

positioning with sub-centimeter levels. The advantage of GNSS over other survey tech-

niques is, that it provides very high temporal resolution measurements, pertinent to moni-

toring time-dependent phenomena, such as the processes occurring in the ionosphere, at-

mosphere and the lithosphere. But space geodetic satellite missions are not limited to

GNSS exclusively. Other missions worth mentioning are: Precise Range and Range Rate

Experiment (PRARE) – the autonomous dual space borne two-way, dual-frequency mi-

crowave tracking system [3] developed in Germany, Doppler Orbitography and Radio Po-

sitioning Integrated by Satellite (DORIS) – the French development with objectives similar

to PRARE , Japanese Experimental Geodetic Satellite (EGS) better known under the nick-

name of “water – snake” or AJISAI. Other countries are readily following the above men-

tioned examples, joinig “the space club”, launching their satellites and expanding the

range of the services and cover of the specific parts of the globe.

Other space missions, which significantly contributed to mapping of our planet and

its resources, were the above mentioned LANDSAT - series (USA), SPOT-series (France),

Shuttle Imaging Radar series (SIR: A, -B, and C, USA), ENVISAT (European Space





Agency, ESA, Europe), RADARSAT (Canada), Shuttle Radar Topography Mission

(SRTM, USA), and commercially operated: IKONOS, QuickBird and OrbView-3 (USA),

and Isaraeli’s commercial system EROS. All of them use the principles of Remote Sens-

ing (RS). That might be defined, as methods and technics to obtain information about the

objects, without the physical contact with them. In comparison with the space geodetic

techniques, in Remote Sensing the broader range of electromagnetic spectrum (EM) is

used. The aim is to monitor the energy level reflected from the surface of the Earth [or

other planets - planetary bodies] or objects placed on them. Thus the type of sensors, their

range [i.e. cover of the specified portion of the EM spectrum] and their sensitivity is of

critical importance. The sensors are usually subdivided into 2 groups: passive and active

[eventually the combination of both]. Advancement in computer science contributed to

computer aided cartography and the development of Geographic Information Sysstem,

generally known as GIS. Thus our perception of the space, mapping of space-time phe-

nomena , the concepts of scale and maps had to be modified, alternatively re-defined. And

so, the terms such as: soft copy maps, fluid scale, or zooming are permanently imbeded in

modern cartographer’s vocabulary. Certainly, not all techniques of Space Geodesy and

Remote Sensing are fully explored and the possibilities of their applications exhausted, as

yet….

Literature: 1. Vaniček P., Krakiwsky E.: Geodesy: the Concepts, North – Holland 1986

2. Torge W.: Geodesy, de Gruyter, 2001

3.Seeber G.: Satellite Geodesy, de Gruyter, 1993

4. van Sickle J.: GPS for Land Surveyors, CRC Press, 2008

5. American Society of Photogrammetry and Remote Sensing: “Manual of Photogrammetry”, ASPRS, 2004

6. Lillesand T., R. Kiefer R., J. Chipman J.: Remote Sensing and Image Interpretation, J. Wiley & Sons, 2007





L 2 - SCIENTIFIC ASPECTS OF GEODESY

Geodesy belongs to a group of so called „hard sciences”, opposite to “ soft scienc-

es” such as Philosophy, Social or Human Sciences. It deals mainly with the Earth and the

phenomena occurring inside the Earth, on its surface, or outside our planet. They all have

an impact on Earth costituence, its behaviour and its position among other planets. The

range of topics of investigation related to our planet is vast. As usual, they are approached

first by observing the phenomena which occure, developing the theories for their explana-

tion, building the mathematical model(s) for describing the phenomena under investiga-

tion, collecting the evidence [representative data] to fit the model, analyzing them, and

stating conclusions which confirm [or reject] the postulated model and/or theories. When

the proposed models do not sufficiently explain the occurring phenomena, but the way of

data collection, size od data sets and their inner homogenity are considered as appropriate

– the models have to be changed, augumented, or the new ones have to be built. Finally,

theories should be modified, or changed; or new one postulated. The important role the

Geodesy plays among other sciences is, that Geodesy provides the quantitative data [as re-

sults of observations or acquisition], which in turn are used by other disciplines. Mainly,

to confirm or reject the postulated theories. Geodynamic might be an exception. It usually

starts from fundamental physical principles to interpret & predict Earth’s behavior, instead

of working backwards from observations. Naturally, the theories are not validated based

exclusively on the results of geodetic observations. The results from related fields, [let it be

Astronomy, Astrophysics, Atmospheric Sciences, Geology, Geophysics, Geology, Mag-

netism or Seismology] are also coming in the play. There is always a question of the selec-

tion and choice of the tools to collect the data. Significant progress has been made within

the last 50 years or so, when space technology tremendeously influenced [i.e.improved] the

way of data collection [vast amount of data], coverage of the regions to be investigated

[change from local (eventually: regional) to global], time scale & frequencies of sampling

of the data. Thus contributing – among others - to better data resolution and allowing for

detection of temporal variation of/within the phenomena. Space technics & technologies

allowed also for the departure from classical data collection [“point by point”] towards

pixel-type of data collection. Where the size of the pixel and its resolution [“footprint on

the ground”] is of importance. The relevance of investigated phenomena determines [or at

least: should determine] the duration of the project {research], its costs, time span, and the

ways of data collection. Typically we must decide, if the monitoring [observations] should

be done in campaigne-type or continuous way. And over what period of the time [called

the” time span”] the data should be collected. Some of the important activities, missions,

and /or phenomena in which Geodesy plays an important [if not: the key] role are : Interna-

tional Earth Rotation Service (IERS) - established in 1987 by International Astronomical

Union (IAU) and International Union of Geodesy and Geophysics (IUGG) for the estab-

lishment of terrestrial reference frame and the control of the rotational behavior of the

Earth. It is based on the following space techniques: Very Long Baseline Interferometry

(VLBI), Satellite Laser Ranging (SLR), Global Positioning System (GPS) and Lunar Laser

Ranging (LLR). IERS Reference System is composed of 2 parts: IERS standards & IERS

reference frames (ITRF). IERS reference frames consist of the IERS Terrestial Reference

Frame (ITRF) and IERS Celestial Reference Frame (ICRF). The Terrestial Reference

Frame has its origin located in the center of the mass of the Earth. It is realized through the

sets of terrestrial fiducial sites & list of their coordinates. The Celestial Reference Frame is





realized through the coordinates of compact radio sources and is based on VLBI observa-

tions. The earth orientation parameters are published in weekly and monthly bulletins and

in annual reports. The important satellite missions, which contributed to improved

knowledge of our planet are [among other]: CHAMP (CHAllenging Mini satellite Pay-

load). GRACE (GRavity And Climate Experiment), GOCE (Gravity and Ocean Circula-

tion Experiment), ICESat (Ice, Cloud and Land Elevation Satellite) and - in earlier days -

GRAVSAT, MAGSAT, and TOPEX/POSEIDON.The important satellite missions for

monitoring & mapping the Earth’s resources based on remote sensing data acquisitions

are: LANDSAT-series (USA), SPOT-series (France), Shuttle Imaging Radar series (SIR:

A, -B, and C, USA), ENVISAT (European Space Agency, ESA, Europe), RADARSAT

(Canada), Shuttle Radar Topography Mission (SRTM, USA), and commercially operated:

IKONOS, QuickBird and OrbView-3 (USA), and Isaraeli’s commercial system EROS.

Geodesy has contributed to faster acceptance of Wegener’s theory of tectonic

plates. Motion of tectonic plates can be monitored with geodetic technics such as VLBI,

SLR, and GPS. The plate motion can be nowadays described with complete models with

respect to uniform reference frame [1]. Commonly used and compared against each other

are : the ITRF and NUVEL models. Examples of the networks and campaignes for moni-

toring the movement of the plate tectonics in selected regions are: Central Asia Tectonic

Science (CATS), Jordanian GPS Activities (JOGA), San Andreas Fault Experiment

(SAFE), South American Geodynamic Activities (SAGA).

The Global Navigation Satellite Systems (GNSS) is under steady development and

refinement. Following the military space systems (USA’s: GPS and Russia’s GLONASS)

other countries decided to launch their own. Examples are: the European Space Agency’s

(ESA’s: GALILEO), China’s BEIDOU/COMPASS, or Japan’s QUASI-ZENITH SATEL-

LITE SYSTEM (QZSS). Certainly, one of the reasons is becoming independent of the

“brass-hats”. Other, is the possibility of interoperability between the systems. Which im-

plies, among other: increased number of satellites (and signals), better satellite availabili-

ties, better dilution of precision, fewer multipath problems or better accuracies in urban ar-

eas.

But the determination of the orbits of the satellites, monitoring the consequences of

the earthquakes {San Andreas fault, Himalaya region, Andes , Japan islands - to mention a

few} volcanic eruption and their prediction {Mt St Helen, Pinatubo, Java},and tsunamis

are not the only applications of Geodesy in everyday life. The navigation in the air, on

land or sea is hard to imagine without GPS. Monitoring the movement of masses within the

Earth, on its surface or lava raise and flow is difficult without the knowledge of the gravity

changes. The extends of catastrophic deseasters such as tsunamis, due to volcanic erup-

tions, lava flow, melting of the ice caps, raise of the oceans, changes in the coastal lines,

land slides, river floods, - to mention a few – are monitored via remote sensing, photo-

grammetry, or terrestrial technics. The results are analysed faster and better displayed

thanks to variety of applications which Geographic Information System (GIS) offers.

The brief sketch presented above is only (as one of my Proferors used to say)

“scratching of the surface”.

As someone said it already before:”Science is the murder of beautiful theories by

the cruel data evidence”





Literature: 1. G. Seeber G.: Satellite Geodesy, de Gruyter, 1993

2. W. Torge W.: Geodesy, de Gruyter, 2001

3. van Sickle J.: Geodesy for Land Surveyors, CRC Press, 2008

4. Lillesand T., Kiefer R., Chipman J.: Remote Sensing and Image Interpretation, J. Wiley & Sons, 2007





L 3 - REFERENCE FRAMES USED IN GEODESY

At the very beginning, it might be worth pointing out, that all reference frames and

reference systems are the matter of their definitions and conventions. But we need them,

in order to relate the results of our observation “ to something” and to be able to compare

or analyse them. Some of them, such as Cartesian or polar coordinate systems are com-

monly accepted and/or adopted. Other, as for example the Geodetic Reference Systems

were [and still are] evolving with time. They were [and still are] refined and modified, as

our knowledge and understanding progresses.

The Earth is not a regular surface. Its first approximation is the sphere. The radius

of the Earth , considered to be sphere is 6 371 km. The position of the points on the sphere

are described by so called spherical coordinates. However the position of the points on the

Earth are commonly known as geographical coordinates [geo=Earth (gr)]. Geographical

coordinates are traditionally denoted by two capital greek letters: Φ and Λ. These types of

coordinates are familiar to users of GPS. Φ – denotes the geographical latitude (counted

from the equator, as the reference plane). Geographic latitude is changing from 0 º - 90 º.

Conventionally, on the northern hemisphere the geographic latitude is considered to be

positive ( “+”); and on the southern hemisphere the geographic latitude is considered to be

negative (“-“). Λ – is called the geographic longitude (counted from Greenwich meridian

). The longitude is changing from 0º - 360º counted eastward from the Greenwich meridi-

an. However is some countries [ for example in USA] the accepted is the subdivision from

0º – 180º. The latitude eastward from the Greenwich meridian is positive (“+”), and west-

ward from Greenwich meridian – negative (“-“). However the Earth is not a sphere. As the

consequence of the Earth’s rotation-among other reasons- the Earth is flattened at the

poles. Thus the radii of the Earth are not equal: the polar radius is ca 21 km shorter than

the equatorial radius. That is not that much, if will consider equatorial radius of the Earth

equal to ca 6371 km. The parameter describing Earth’s flattening is usually denoted by f .

It is the ratio of the differences between the Earth’s radii (equatorial minus polar) to equa-

torial radius of the Earth. Earth’s flattening is ca 1: 298, 25. So, because the radii of the

Earth are not equal, the next [and more precise] geometrical figure to approximate the

Earth is the ellipse [at the cross-section], or, better said: rotational ellipsoid [as the Earth is

rotating around its axis]. The rotational ellipsoid is the mathematical figure, which de-

scribes [more precisely than the sphere] the position of the points on [but also: above or

below ] it. But the actual figure of the Earth is known as geoid. It is the figure, which equi-

potential surface of Earth’s gravity field coincide with the mean sea level. Thus if we de-

note the gravity potential as W, we may state [write], that for geoid W= constant. Another

definition, which is probably easier to remember [or: imagine] is, that geoid is the sur-

face perpendicular to plumb line. Geoid is considered to be a closed and continuous sur-

face, which extends partially under the continents. Its curvature displays abrupt density

changes. Examples are the changes of densities on the boundries such as: air-water, air-

rocks, or water-rocks. Geoid is not an analytical surface [in the global sense]. However it

may be sufficiently approximated with mathematical tool called spherical harmonic ex-

pansion. The geoid plays an important role in geodesy and oceanography as a height refer-

ence. Nowadays we are approaching the “cm” accuracy level of the geoid [1]. Since the

heights coming from leveling are related to geoid [as refence surface], but heights coming

from GPS are related to reference ellipsoid, the knowledge of separation between the el-





lipsoid and the geoid is very important. If we know them with sufficient accuracy, then we

can convert the geoidal heights to ellipsoidal heights [and vice versa]. Geoid plays also the

vital role in Geophysics, particularly in Geophysical Exploration. As the changes in gravity

might imply existence of some minerals or energy sources such as gas, or oil.

As mentioned before, we need some reference system in order to relate the results

of our observations to a common system, thus to be able to compare and analyse them.

Although for non geodesist, the section presented below may seem somewhat awkward [or

strange], we’ll briefly summarise the most important [common] reference frames in Geod-

esy. They are known as GRS-80 and the WGS-84. In year 1979 in Canberra, the Interna-

tional Union of Geodesy and Geophysics (IUGG) introduced Geodetic Reference System

1980 (GRS-80). It is based on the theory of geocentric equipotential ellipsoid. The minor

axis of reference ellipsoid is parallel to the direction defined by Conventional Internation-

al Origin (CIO) and the primary meridian is parallel to zero meridian of the Bureau Inter-

national de l’Heure’s (BIH) adopted longitudes. The following constants were defined:

Equatorial radius of the Earth: a= 6 378 131 m

Geocentric gravitational constant of the Earth (including the atmosphere) GM =

398 600.5 x 10 9 m3 s2

Dynamical form factor of the Earth (excluding the permanent tidal deformation) J2 =

1 082.63 x 10-6

Angular velocity of the Earth’s rotation ω = 7. 292 115 x 10-5 rad s-1

This system is consistent with the 1976 International Astronomical Union’s (IAU)

system of astronomical constants [1].

GPS measurements are referred to World Geodetic System (WGS), which latest

version from the year 1984 is known as WGS-84. The defining parameters of this systems

are as follows [1], [2]:

Semimajor axis of the Earth a = 6 378 137 m

Reciprocal flattening 1/f = 298. 257 223 563

Geocentric gravitational constant of the Earth GM = 398 600.4418 x 10 9 m3 s2, which

includes the atmospheric part GMatm = 0.35 x 10 9 m3 s2

Angular velocity of the Earth’s rotation ω = 7. 292 115 x 10-5 rad s-1

2nd zonal harmonic C2,0 = - 484.16685 x 10-6

The associated with WGS-84 gravity field in is given by the Earth Geopotential

Model from year 1996, known as EGM 96. As we may notice, the WGS-84 partially coin-

cides with GRS-80.

For Europe the European Terrestial Reference Frame (ETRF) exists, which was

defined for the epoch 1989 (ETRF 89). In year 1999 it consisted of ca 200 stations, with

separations between them ranging from 300-500 km. ETRF should rotate with the stable

part of European tectonic plate. That ensures that this frame remains unchanged over long-

er intervals of time. In Poland there are 11 stations of ETRF, which coordinates were de-

termined in 1992. They were adopted by International Association of Geodesy (IAG) in

1994 as part of European Reference Frame (EUREF) and are known as EUREF-POL.





EUREF-POL was next densified in Poland with ca 350 stations. The name of this network

is POLREF.The separation between the stations is ca 30 km. EUREF-POL and POLREF

created the base for adjustment of an old astro-geodetic network and triangulation (of the I

class), and horizontal network (of the II class) in Poland.

As mentioned before, the concept of geoid is one of the fundamentals in Geodesy.

The definition of geoid was slightly modified over time. One of them says that “geoid

could be defined as the equipotential surface which best fits mean sea level at certain

epoch” [1]. Geoid is of particular importance when dealing with heights. Because it serves

as the height reference surface. Besides different mareographs, used as reference points for

national, or regional height determination [i.e. establishment of leveling networks], there

are also different concepts of heights used in Geodesy. Examples of which are:

Dynamic height (Hdyn), which is obtained by dividing geopotential numbers

[i.e. the negative potential difference of point P to the geoid] by the constant gravity value

at 45 º latitude ( γ 0 45). When Hdyn is constant, it determines the equilibrium surface

Orthometric height (H), defined as the linear distance between the surface

point and the geoid reckoned along the curved plumb line [ although it may come as a sur-

prise for someone, that plumb line is curved]

Normal height (HN), which is obtained by dividing the geopotential number

( C ) by mean normal gravity ( γ ). The reference surface for the normal height is quasi-

geoid [in Poland: Molodensky’s quasi-geoid]

Vertical datum, called also Zero height surface of national height system

[such as, for example The North American Vertical Datum (NAVD)]. It is defined by

mean sea level, derived from long time observations of tide gauges records

Level surfaces, known also as geopotential surfaces. These are the surfaces

of constant gravity potential

References:

1. W. Torge W.: Geodesy, de Gruyter, 2001

2. Seeber G.: Satellite Geodesy, de Gryter, 1993

3. Jagielski A.: Geodesy (in polish), Geodpis, 2005





L4 - GEODESY, GEODETIC SURVEYS and PLANE SURVEYING

Geodesy is a part of geosciences and engineering sciences, including navigation

and geomatics. It may be divided into the areas of global geodesy, geodetic surveys (na-

tional and supranational), and plane surveying [1]. “ Global geodesy includes the determi-

nation of the size and the shape of the Earth, its orientation in space, and its external gravi-

ty field. The geodetic survey stands for determination of Earth’s surface and gravity field

over a region that typically spans a country or a group of countries. The Earth’s curvature

and gravity field must be considered in geodetic surveys. In plane surveying (topographic

surveying, cadastral surveying, engineering surveying), the details of the Earth’s surface

are determined on a local level, and thus curvature and gravity effects are generally ig-

nored.” ([1], ibid.)

There is a close relation between these three divisions. Geodetic surveys are linked

to geodetic networks, which are established by global geodesy. These surveys adopt the

global parameters for the figure of the Earth and its gravity field. The results of the geodet-

ic surveys may however contribute to the work of global geodesist. Plane surveys are gen-

erally referenced [related to] control points established by geodetic surveys. Plane surveys

are used in the development of national and state map-series, cadastral information sys-

tems and in civil engineering projects. There is a close relation [ i.e. interdependence] be-

tween all of them. Space methods , which originated and prevailed in global geodesy are

nowadays commonly used in geodetic surveys and plane surveys as well. To perform

these kinds of surveys properly, the knowledge of the detailed Earth’s gravity is required.

GPS, GLONASS and Galileo are good examples.

In Poland, Geodesy is subdivided in the following way [2]:

1. General Geodesy, which deals with measurements [surveys] and making maps of

small areas, i.e. without considering the curvature of the Earth

2. Higher Geodesy, which deals with size & the shape of the Earth. The surveys are

done [performed] on bigger areas, where the curvature of the Earth is considered

3. Cartography, which is the science about maps, methods and ways of making them.

Also, about the ways of using the maps

4. Topography, which deals with making “general-geogpaphic” maps, which scales

range from 1:5 000 to 1: 100 000

5. Photogrammetry, which is the technique of making, producing & utilizing ground, -

aerial and -satellite’s photos for the survey puposes and making the maps [i.e. cartography]. Photo-

grammetry used for map making is called phototopography or photogrammetric topography

6. Surveying Instruments, dealing with construction, checking [adjustment], utilizing

and service [maintenance/use] of surveying tools

7. Adjustment Computation, dealing with methods of computation, adjustment of sur-

vey results, solving the sets of equations for the [most probable values of] unknowns, analysis of

the results from the adjustment, optimization of geodetic work & ensuring the fulfillment of speci-

fied accuracies under given [initial/assumed] conditions

8. Economic Geodesy, with a broad range of application of geodetic methods in differ-

ent branches of state management and economy [such as: administration,industry, agriculture, min-

ing, railways etc]. There are the following specializations within this discipline: surveying enge-

neering, cadastral surveying, forest surveying, mining surveying, railway surveying





9. Dynamic Geodesy, dealing with the shape and spatial placement [position] of the ge-

oid. It is founded on the gravity surveys, from which the acceleration and gravity potential can be

estimated [determined]

10. Geomatic, also known as Geoinformatic, which is closely related to computer sci-

ence. Geomatic deals with problems related to data: acquisition, transmission, analysis, manipula-

tion & release. These types of information are called space georeferenced information. The basis

of which is Geographic Information System (GIS)

Although basically correct, this subdivision is, however, somewhat obscolete. Dy-

namic Geodesy is considered as part of Geodynamics.It plays an important role in Dy-

namics of the Continents [interior, roots and margins], Intra-plate Volcanism [origins,

causes and consequences], and Earthquake Dynamics [including tsunamis]. In English

speaking countries there is the difference between Geomatic and Geoinformatic [although

the term “ Geomatic” is still somewhat vague, and there are several distinctively different

definitions, of what “Geomatics” actually means]. It is hard to distinguish nowadays

[or:draw the clear line], where Geodesy ends up and Surveying starts. In English speaking

countries there is an attempt to to cover this gap, [or: “pave the bridge” between Geodesy

and Surveying] , through concept of Geodetic Surveying, or Geodetic Surveys. Interesting-

ly enough, the term: Geodetic Survey was created [“coined”] in US mostly by the people

coming from neither Geodesy, nor Surveying [i.e. outside of either specialization].

In the USA the ranking of surveying profession does not have the tradition and

prestige as it has in Europe. The main reason is, that surveys in the US were mostly done

by Civil Engineers. Until recently, there was no formal education in Surveying in the

USA. The lawyers who have the power to overturn some of the decisions and statements

made by surveyors [although the lawyers hardly have the knowledge of simple trigono-

metric functions, not to mention the surveying methods and the technics ] took advantage

of this situation. In some parts of the USA transits (i.e. the optical-mechanical instruments

with verniers and four foot screws) are still in use. And the conversion to SI units is going

very slowly. It seems however, that development in electronic, total stations and robotic

type of instruments will soon bridge this gap. Also the advancements in GPS technology

and GPS receivers suited for performing the surveys should soon even out these discrep-

ancies. Geodesy in the USA was mostly linked with either Geology [ in earlier days] or –

later on – with Geophysics. The political subdivision of Canada (the French dominated

Quebec and the fact, that Canada officially is still considered to be the part of “Britisch

Kingdom”) seems to be a contributing factor to the existing situation in Canada. Contrib-

uting factors to existing situation in Canada seem to be the political subdivision of Cana-

da: The SI system was adopted in Canada and has still been in use.

Literature:

1. Torge W.: Geodesy, de Gruyter, 2001

2. Jagielski A.: Geodesy, Geodpis, 2005 (in polish)

3. Kahmen H.: Vermessungskunde, de Gruyter, 1997





L5 - SENSORS. THEIR APPLICATION IN SURVEYING

Our every day life is influenced by the developments coming from the fields of

micro electronic and computer science. We have no choice, but accept and adopt the inven-

tions, which new technology is offerring. The role of sensors and their role in the industry

and fields dealing with measurements is gaining the momentum and importance. The im-

pulses coming from developments in microelectronic are stimulants for the new sensors to

be made. They allow the development of modern instruments and techniques for both:

survey and capture of different phenomena [such as for examples bending of the beams

under load in construction, elements of bridges under heavy traffic, or deformation meas-

urements in surveying] through better, improved treatment of the signals. Until recently,

the knowledge of optics and basics from mechanics was sufficient for the surveyors to per-

form their surveys. However in last decades it changed dramatically. Electronic sensors

used in one dimensional measurements [i.e. distance, angle and hight], two dimensional

measurements [use of CCD array cameras as receivers, development of computer aided

systems and three dimensional measurements [related/referenced to position, form or tra-

jectories of objects of interest] have found the permanent place in surveyors life. To en-

sure, that the tasks are accomplished under specified accuracy criteria, it is not sufficient

to know which bottons to push. The surveyor must know and understand the basic princi-

ples of the tools he/she has in the hands to get the job properly done. Moreover, one should

also know, how the results are obtained, so that one knows the sources of possible errors.

Also, it is necessary to know of how to control and minimalize their impact on the results

of the surveys. It is impossible to do that without the deep and throughout knowledge of

the sensors and understanding of how they work [i.e. function]. In the same way as we

learned in the past the basic principles of optics and mechanics to understand of how the

theodolites, transits and levels function, we must nowadays comprehend and to augument

our knowledge through the basics of electronic and sensors. It is necessary, as we must

make the right decisions, when it comes to evaluation of the error budgets, how to limit or

control them with the tools we are given [or have in our hands].It might be that the thor-

ough knowledge of electronic and sensors is not necessary. However, we should have the

overview of the entire spectrum of possibilities, the electronic and sensors are offering in

the fields of our specialization. That will certainly be advantegous while making the right

decision, i.e. selecting the proper instruments for the task to be accomplished, or choosing

the appropriate methods of the surveys. The knowledge of the vocabulary coming from

these areas is also necessary. Without it, the communication and mutual understanding ,

even between everyday partners, such as for example the project manager and the surveyor

is not possible to accomplish the tasks properly done [not to mention the professional dis-

cussions, or posing the right questions [i.e. to salesmen, or instrument makers]. Particu-

larly that English professional language and literature are full of abbreviations.

Proposed is “new”, or different look at phenomena such as: the light [as a narrow

portion part of electromagnetic (EM) spectrum], light rays [as beams of wavelengths with

specified lenghts], interference and polarization of light and its applications in surveys [

parallel plates, mirrors, lenses; but also its use in (for example) deformation measurements

[i.e. method of constant reference line], optics [as interaction between two (or more) me-

dia with different density and cristal structures [or: constituencies]], materials used for the

production/making of modern instruments [metal, plastic, but also cristalls of certain min-





erals such as kalcit, or quarz used in liquid cristal displays (LCD)], or signals processing

(i.e. varieties of signal modulation techniques).

Considering the applications of sensors, they may be divided in 3 classes:

Sensors for geometrical properties

Sensors for mechanical properties

Sensors for the temperature

In modern surveying instruments [such as tachymeters, or robotic total stations] the

components for electronic distance measurements (EDM) are built in. They are the integral

part of the measuring systems. The lengths of electromagnetic waves used for the distance

measurements range from microwaves to visible light [wavelengths (λ) from 1 m to 10-6 m]

[1]. The equipment usually consists of electronic unit and a retro prism. The electronic

unit transmits the waves [signals] to the prism, which reflects it back to the unit for analy-

sis. Thus the double slope distance between the two points is measured. Some of the direc-

tions in development of tachymeters/total stations are listed below. These are: 1) increas-

ing the range of the measured distances; 2) measurement with and without the retro-prism;

3) built-in servomotors, which eliminate manual operation of the instrument; 4) one man

system, i.e. possibility of controlling the measuring unit from the position of the range pole

and retro-prism ; 5) self-calibration and automated search for the prism/target; 6) integra-

tion with GPS receivers; 7) built-in scanners or digital cameras for recording the surveyed

objects (“as built”) or the the stake-out; 8) tracking and recording of the moving objects; 9)

simplicity and ease of use [related to both: the keyboard and the built-in software]; 10) in-

creased capacity of memories [internal and external]; 11) longer time span of the charged

batteries; 12) direct data transmission from the field to an office; 13) apart from being built

as water-and dustproof, they also have an increased robustness.

Although the results of conventional surveying techniques are reliable, they howev-

er have their limits when: a) objects are moving very fast or deformations are very rapid

[i.e. visual observations are too slow to “catch” the phenomena];b) the movements of many

objects should be measured/recorded simultaneously and their deformations should be

measured at different moments; c) 3-D position and deformation should be measured in

large quantities and the consequtive measurements should follow in very short time inter-

vals. Examples might be the crash tests of new cars ‘ models, before their series produc-

tion, or analysis of the athlets’ bodies [i.e. while swimming, running, etc.].

The limiting factors are: 1) the velocity and the direction of data flow; 2) the form

in which the results should be presented [that is called “modelling”].

The solution is on-line measurement, in real time. This can be done by merging

surveying measurement techniques with CAD and the development of control and the nav-

igation routines. Some of these systems are already used. Examples are:

CAPSY {(Computer Aided Positioning System)

CIM (Computer Integrated Manufacturing)

DOM (3D – Online – Measuring Systems)

LPS (Local Positioning System)





Literature:

1. Buckner R.: Surveying measurements and their analysis, Landmark Enterprises, 1983

2. Schlemmer H.: Grundlagen der Sensorik, Wichmann, 1996

3. Deumlich F.: Instrumentenkunde der Vermessungstechnik, VEB Verlag fuer Bauwesen, Berlin





L6 - Types of leveling. Height reference system in Poland.

The determination of horizontal planes, heights or height differences was one of

the tasks people have been trying to do since ancient times. Over the years the methods and

technics of height, or height differences determination have been refined. But even today

the vials and similar simple instruments are in use. One of the instruments commonly used

on construction sites to determine the heights or height’s differences are levels and the lev-

eling rods. If the instrument is levelled [set up perpendicular to the plumb line] by taking

the readouts between any two visible points [by placing the leveling rods on them], we are

able to determine the height difference between these points. It is done in a simple way:

just by making the difference between the two readouts from the leveling rods.This is

known as geometric [technical] leveling. Another way of determination the height differ-

ences is with the use of the laser levels. The inclined laser beam is rotating, and where the

beam is intersecting, the horizontal plane is determined. Knowing the horizontal [refer-

ence] plane, we are able to determine the height differences. These are the two most com-

mon methods, we encounter on variety of construction sites. However, there are also other

methods to determine the height, or height differences. These are known as leveling, or

leveling procedures [methods]. Among them we distinguish:

Barometric leveling. As we know, the pressure of the atmosphere is decreasing with

the elevation. This principle is used in barometric leveling. Instruments such as quick silver barom-

eters and aneroids are used. However, the accuracy of height determination with this method is

usually of order of several meters; in the best cases of several decimeters. As it depends on factors

such as: the weather condition, temperature of an air, water wapour pressure, humidity or geo-

graphic location where the height determination takes place. So it is rarely used nowadays; and

mostly for the preliminary studies

Trigonometric leveling. Knowing the distance between the points and the vertical

angle between them, we can compute the difference in elevation with simple trigonometric relation

[Δh=D * tg ά, where: Δh is the height difference, D-distance between the points, ά-vertical angle].

The accuracy of this method is depending of the instruments used, and particularly: precision of

the distance and vertical angle measurement. But the weather conditions have to be considered,

too. The precision of this method is of order of several centimeters. Although much better results

[of order of several millimeters] were also achieved. There were also attempts to use this method in

so called “motorized leveling”.

Geometric leveling. Here we distinguish between the technical and the precise level-

ing. The principle is the same. However, the main difference lies with the instruments and methods

applied. As for precise leveling we use the levels with better parameters, such as magnification,

precision of taking the readout, and marking of the points, between which the height difference

should be determined. Also, the weather condition, season of the year and the time of day [or

night], when the survey should be performed should be carefully chosen. The accuracy of precise

leveling depends – among others – on the distance and the chosen way to determine the height or

height differences. But its usually below milimeters level. On the other hand, the accuracy of tech-

nical geometric leveling is of order of several millimeters.

Hydrostatic leveling. In hydrostatic leveling the method of communicating vessels is

used. Hydrostatic leveling is based on the principle, that liquid in state of balnce is determining the

same [reference] plane. Usually the connected vessels are filled up with destilled water. The range





of hydrostatic leveling is limited to relatively small areas. It is used in some engineering projects,

mostly related to periodical checks of the heights, or refernce points [ called the benchmarks] in

specified areas. This method is labour-intensive and time consuming. But its one of the most pre-

cise methods to determine the heights or heights differences. Usually the accuracy of hydrostatic

leveling is within 0,1 – 0,01 mm.

Leveling with GPS. The accuracy of height determination with GPS is within several

centimeters. Recently more and more GPS receivers are mounted on construction equipment, such

as buldozers. Its because this accuracy is sufficient for some jobs on construction sites, such as

grading, or slope determination. However, one should be aware, that heights obtained with GPS

leveling are referred to reference ellipsoid [ellipsoidal heights] and not to geoid [as other types of

leveling are]. So, if we would like to compare the GPS leveling against the results from other level-

ing methods [techniques], the separation between the geoid and the reference ellipsoid has to be

considered [encounted for].

Direct determination of the height differences. This can be done by placing the

steel tape [with some kind of plum bob or other heavy device at one of the ends], or other graduat-

ed device [like leveling rod] perpendicular [which means: along the plumb-line] to the points where

we need to know the height differences [for example along the face of the wall or building, the pil-

lar, the column etc.]

The geoid is the height reference surface in leveling. The heights referred to geoid

are known as geoidal heights. However, the heights obtained with GPS measurements are

referred to reference ellipsoid. Thus, we must know the geoid-ellispsoid height differences

[known as :geoid-ellipsoid separation], if we would like to compare the results from lev-

eling with those obtained with GPS. This is particularly “tricky” in the areas, when the ge-

oid’s slope is changing, i.e. from negative to positive, or the other way around. As in some

areas the geoid might be above , and in others-below the reference ellipsoid.

The height reference system in Poland is based on so called “normal heights” re-

ferred to Molodensky’s quasi-geoid. Normal height is the difference of gravity potential

between the geoid and the given point. Quasi-geoid is the surface of oceans, seas and those

points below the Earth’s surface, for which the average value of normal gravity [denoted in

literature as γ] is equal to the average value of gravity [denoted in literature as g]. Heights

in Poland are referred to Kronschtadt’s mareograph [of Baltic Sea, in Finnish Bay, close to

Sankt Petersburg, in Russian Federation]. Another mareograph commonly used in Europe

is the one of Amsterdam.

Literature:

1. Torge W.: Geodesy, de Gryter, 2001

2. Jagielski A.: Geodesy, Geodpis, 2005 (in polish)

3. Kahmen H.: Vermessungskunde, de Gruyter, 1997





L7 - Terrain Analysis

Every architect, civil engineer, developer, geologist, land planner and surveyor is

aware of the importance of terrain configuration. The surveyor’s concern is mostly related

to selection of the vantage sites for establishment of the points of the network, and - alter-

natively - their monumentation. From these points he/she could either perform the survey,

or continue densification of the network further. It was customary to separately establish

horizontal network and separately the vertical network. Nowadays, the so called 2-

functional networks [i.e. horizontal and vertical simultaneously] are commonly used. [i.e.

established, when needed]. Nevertheless, the knowledge of the terrain, its landforms, origin

and configuration should be an integral part of professional training/knowledge. The pur-

pose of the topographic surveys is to present the terrain in the way, which is understood by

specialists from related fields. These are mostly architects, civil engineers, land planners

and land developers. The surveyor should place on the sketch of the survey, besides the

numbers (and alternatively: elevations) of the measured points, also the characteristic lines

(called also: the pattern of the landforms, or “skeletal lines”) of the surveyed terrain. These

are: the ridge lines [and the direction of their slopes],the runoff lines [and directions of the

flow towards the streams/rivers], the banks of the streams/rivers, and the abrupt changes in

elevation [such as: ditches, pits, canyons]. Also, indicated on the sketch should be the

measured points, between which the interpolation of contour lines (i.e. the lines connect-

ing the points at the same elevation) should not be done [performed]. The results of the

surveys of the terrain are displayed on the map or plan. The plan is sometimes called the

“blue print”. The difference between the two is mostly in the scale. The blueprints [plans]

are usually made in bigger scale [i.e. small denominator, for example: 1:250], as compared

to maps [i.e. bigger denominator, for example: 1: 5 000]. Maps are usually made with

some kind of carthographic projection, whereas the blue prints [plans] are usually lacking

it. Traditionally either maps or plans should be done in the pre-determined [i.e. fixed]

scale. They should “adequately” represent the measured terrain. Its features are presented

with conventional signs. The elevations are shown with countour lines. The separation be-

tween the contour lines is mostly depending on the scale of the map [plan]. In some cases

the scale of the map [plan] is specified: either by agencies awarding the projects, or by the

contractors/developers. Photogrammetry and Remote Sensing significantly contributed to

development in interpretation and analysis of the terrain. Photo and image interpretation

are well established tools. They possess several unique factors, which are important for da-

ta collection. Among them are: the representation of conditions, which existed during the

exposure; coverage & overview of relatively large areas; 3-D viewing aspects, which facil-

itates the depth perception. The photo interpreter should follow the principles [rules] of

pattern recognition using the indicators such as: size and shape of the objects, pattern

[which is relatively difficult to observe on the ground, but easily seen from the air; exam-

ples are: drainage, pipelines, highways or railroads]; tone [which provides information re-

lated to different soil types, their moisture, conditions, crops and manmade materials]; the

texture [the density of which may suggest the same crops or rock types, or allow to distin-

guish between different types of them]; shadow, which in some cases is the primary ele-

ment in image recognition [for example: the vertical chimneys, smokestacks, firetowers

and oil derricks are sometimes difficult to spot (or which might be overlooked on images),

but are easily identifiable by their shadows; many foresters also observe the tree shadows





for branching patterns identification, so that they can be correlated with certain spe-

cies].There is a range of engineering and construction problems, which should be consid-

ered early in the planning process, before the development begins. These are the physical

site requirements and capabilities for sewage and solid waste disposal, trenching, excava-

tion and grading, dewatering, sources of construction materials, compaction of fills, pond

or lake construction, as well as foundation and highway construction. The capability of a

landform to support sewage system depends upon its characterictics of slope, depth of wa-

ter table and bedrock [or other impervious stratum] and of the soil percolation rate. Solid

waste disposal is best, when is disposed as sanitary landfill system. The ideal location for

it, is the natural, or manmade depression underlaid by an impervious stratum. Depth of

seasonal water table, soil permeability and suitability of the materials are important factors

to be considered. The soil materials covering each day’s deposit of wastes should be ade-

quate to provide an impervious layer. In that way the rainwater does not penetrate and

forms the leaches. When it comes to trenching [regardered here as temporary trench exca-

vations of depth up to 7 m], the physical site conditions influence the difficulties and de-

termine the cost during the trenching.These are: soil composition, cohesion, water table

depth, soil depth, stoniness and rock typer. Same holds for excavation and grading. These

operations are related to removal of earth materials to create either large, flat sites for land

uses [airports, industrial parks, or commercial shopping centers]; or pit excavations for the

construction of foundation structures. As for dewatering, soil permeability is the most criti-

cal factor in determining the amount of water that enters the given size of excavation over

time.. The flow of water from the water table must be decreased to an insignificant amount

in order to allow for safe and efficient removal operation. Construction materials are rating

as: not suitable, poor, fair, good and excellent. They are evaluated relatively to general ca-

pability of various landforms to supply them. Among generally suitable construction mate-

rials we distinguish: topsoil, sand, gravel, aggregate, surfacing, borrow and building stone.

When soils are excavated to be used as fill, many of their original characteristics are signif-

icantly modified. These are, in particular: the average porosity, permeability and compress-

ibility, which all increase. To avoid excessive settlement of the fill over time, its a common

practice to compact soils in layers, as they are deposited for fills. The extent to which the

soil can be compacted under specified procedure is primarily depending upon the water

content in the soil. Groundwater table is defined as the level at which permanent, saturated

conditions are found. The seasonal high water table in soils may, or may not reflect the el-

evation in ground water table. Groundwater supply for municipal needs depends on many

factors; but permeability of the water - bearing strata is one of the most significant. When

it comes to search for potential sites for agricultural pond, large lakes, or regional reser-

voirs, data supplied by satellite images, aerial photographic interpretation and landform

analysis can be used to identify the most attractive sites.The major factors for the selection

of that site are: 1) the physical charcterictics of the valley (including landforms, soils, area,

and dimensions); 2) the occurrence of previous landslides or potentially unstable zones; 3)

the characteristic of watershed area (including drainage net, vegetative cover, land uses,

and potential sedimentation); 4) the supply of construction materials to be used for dam

construction and to provide a suitable bottom seal; 5) the physical site characteristics that

affect the location and design of a dam, spillway, or major associated structures. The eval-

uations are made based upon: a) suitabilities of an associated soils as impervious bottom

materials for preventing the leakage; b) problems of placing the dam structure; c) possible





situation hazards, with recommendations for their prevention by proper watershed man-

agement.

Literature:

1. Way D.: Terrain Analysis, McGraw-Hill, 1978





L8 - Photogrammetry. Basic Terms and Applications

Photogrammetry is the science and technology of obtaining spatial measurements

and other geometrically reliable products derived from photographs. It may be divided as:

Mono and stereophotogrammetry [one & two picture/images]

Topographic and non-topographic photogrammetry

Terraphotogrammetry [when the photos/images are taken from the ground],

Aerophotogrammetry [when the photos/images are taken from above the ground],

and

Satellite photogrammetry [when the photos/images are obtained from the platform

placed several hundred kilometers above the Earth’s surface]

Mono-photogrammetry deals with single photogramms, representing the image or

the object(s) of interest. In stereophotogrammetry-the pair of photos/images, called the ste-

reograms are used. That allows for the 3-D view of the objects registered on the pho-

tos/images. Thus the advantage of the depth perception can be fully explored and used

while analyzing /interpreting the objects [i.e.extracting the information about the objects

registered on the photos or images]. Topographic photogrammetry is used to produce the

topographic maps. Nontopographic photogrammetry is applied to document and to analyse

ground objects [usually in the large scale].

Until recently most ground & aerial photogrammetry was based on emulsion,

which was coated either on the glass plates, or film. Development of the photos was made

with chemical treatment of the emulsion, previously exposed to the light. So, the “hard-

copy”, or: analog photogrammetry dominated the market & the map production [until late

60-ties]. Nowadays both: emulsion/film-based and the digital photogrammetry are widely

used. Digital, or: “soft-copy photogrammetry” is any photogrammetric operation involving

the use of digital raster photographic image data instead of hard-copy images. It might be

of interst to mention, that ca 90% of the worldwide maps are produced with photogram-

metric methods. Photogrammetric products such as colored orthophotomaps [i.e. maps ob-

tained with “differentially recified” photographs, which geometric accuracy - particularly

with respect to elevation – is superior to conventionally rectified photogramms] or the

Digital Elevation Models (DEM) are widely used in Geographic Information Sysytem

(GIS). The advantages of aerial photos/images and aerial photogrammetry over the ground

phots/images and photogrammetry are enormous. Some of them are listed below:

Improved vantage point. The coverage of the terrain is usually bigger and no special

points (camera sites) have to be selected a priori

We can see the whole picture. And all observable elements (Earth’s features) are

recorded simultaneously

Capability to stop the action. Photography and Photogrammetry are particularly

useful to study the dynamic phenomena, such as wind load on the structures, flooding, oil spills,

forest fires, traffic congestion at the peak hours, migration of the wildlife and similar

Permanent recording. The photos & aerial photos (or images) have documentary

character. Its often used – and taken advantage of – for example when giving the speed tickets and

wrong parking of vehicles





One photo/image can be used by many users. Each of the user might be interested

in extracting different information from the same image/photo/ aerial photo

When taken over a period of time in the same region/area/or of the same objects, they

can be used to monitor the changes (so called: “change detection”)

Broadened spectral sensitivity. It is because we can record the broadened electro-

magnetic spectrum (EM): ultraviolet (UV) and infrared (IR) with photographs (both: ground and

aerial) and images. By using this kind of photos/images, we can “see” what human eyes cannot.

For example: discharged hot water spilling into reservoir, or heat-loss in poorely islolated buildings

Increased spatial resolution. That can be achieved with proper choice of the flight

parameters, types of sensors, or types of the cameras used

Geometric fidelity. Assuming that distortion of lenses is negligible and the sensors

are functioning properly, we can actually perform the measurements on the photos/images with

proper ground reference . That significantly saves the man-power and costs of map productions

Unquestionable advancement in photogrammetry [in particular: aerial photogram-

metry] came with the use of the GPS. This technology is widely used to position air vehi-

cles [airplains, helicopters, balloons] and ground based reference stations. That virtually

eliminates the need for the labour-intensive “ground control”. Ground control is estab-

lished by “marking” on the ground (and thus making visible on the photos/images) the

identifiable reference points, called also “photopoints”. [although some of well identifiable

control points may still be used, for example to calibrate the air photos/images]. Some of

the topics addressed in photogrammetry include:

Preparation of the flight plan to acquire aerial photography

Determination of the scale of vertical photographs [as the scale of vertical photo-

graphs varies with elevation]

Estimating ground distances from measurements made on vertical photographs (to

calculate the areas, ground coverage, etc.). Once the scale of photographs is known at any particu-

lar elevation, ground distances at this elevation can be estimated

Production of so called “orthophoto-maps”. Once relief displacement is carefully ana-

lysed, and considered, then reliable maps can be produced. Relief displacement on the aerial pho-

tographs causes any object standing above the ground [terrain] to “lean away”- radially from the

principal point of the camera. Othophotos are identical with conventionally rectified photographs.

However, their geometric accuracy, if the terrain is not completely flat, is superior.The orthophoto

technique is relatively simple. This technique is suitable for mass production and automation

Determining the height of objects from relief displacemet measurements. The magni-

tude of relief displacement depends on the flying height, the distance from the photo’s principal

point to the features to be measured, and on their heights. Since these parameters [quantities] are

geometrically interrelated, we are able to determine the height of the objects of the features record-

ed on the photographs.

Literature:

1. American Society of Photogrammetry and Remote Sensing (ASPRS): Manual of Photogrammetry ,5th edi-

tion, ASPRS, Bethesda, Md, 2004

2. Lillesand T.M., R. W. Kiefer R.W., J.W. Chipman J. W.: Remote Sensing and Image Interpretation, J. Wiley

& Sons, Inc., 2007

3. Butowitt J., Kaczynski R.: Photogrammetry WAT, Warsaw, 2010, (in polish),





L9 - Remote Sensing. The Concept and the Principles.

“Remote sensing is the science and art of obtaining information about an object, ar-

ea, or phenomenon through the analysis of data acquired by the device that is not in contact

with the object, area, or phenomenon under investigation” [1]. Right now, as you are read-

ing this text, you are actually applying remote sensing principle. The Roman letters are ap-

pearing on the screen /paper/. They stimulate our senses and are absorbed by them. Our

brain separates them from the blank screen /paper/ and forms them in words [data]. The

words are combined in sentences [data sets]. These are processed by our brain [computer].

We recognize them and interpret the information which sentences convey. Another exam-

ples might be looking at the pictures /photos/ or watching TV. Gravimeters or gradiometers

acquire the information about the gravity force (eventually its variations) . Sonar obtains

the data about the variations of the acoustic waves distribution. Our senses register only the

certain portions of electromagnetic spectrum. One of the advantages of using sensors in

remote sensing is, that they may register signals in broader spectrum then our senses can

do. Thus we may obtain the information about phenomena that we can’t see with our eyes

[for example when its occurring in the invisible portion of an electromagnetic [EM] spec-

trum: like ultraviolet [UV] or Infrared [IR]]; or which we cannot hear (with our hearing).

Remote sensing is concerned with EM spectrum. Its based on energy sources, the princi-

ples of radiation, energy interaction in the atmosphere (such as: scattering, and absorption)

and the Earth’s surface features. The Sun and the heat generated inside the Earth [as result

of nuclear reactions taking place there] are the main sources of energy. Spectral reflectance

and the response patterns play an important role in pattern recognition. Features such as

asphalt, concrete, clouds, rocks, sand, soil, snow, vegetation, and water have different re-

sponse patterns. Although they are “spectrally separable” it is vital to be able to distinguish

between these boarders of separation. It is not an easy task, as factors such as atmospheri-

cal and geometrical influences on spectral response have to be considered. The selection of

the sensors also plays an important role. Particularly their type and the pre-selected range

of their spectral sensitivity within the EM spectrum. Consequently the platform on which

the sensors are placed is the next important task . The sensors may be placed on the

ground, or just above its surface ( i.e. hand held spectroradiometer, or photogrammetric

camera attached to the tripod); or in the vehicles flying on low or high altitude (i.e. lidar,

aerial videography); eventually on boards of satellites (i.e. Shuttle Imaging Radar). That is

called the multistage remote sensing concept. Features may be recorded as point, line, or

area features. Examples are: determination of well depth (point feature), highway/rail

tracks/power lines (line features) or soil mapping units (area features), respectively. Re-

motely sensed data have to be validated. That can be done through reference data. The

referernce data might serve any, or all of the following purposes:

To aid in the analysis and interpretation of remotely sensed data

To calibrate the sensor

To verify information extracted from remote sensing data

Successful application of remote sensing involves:

1. Clear definition of the problem

2. Evaluation of the potential for addressing the problem with remote sensing techniques





3. Identification of data acquisition procedures appropriate for the task

4. Determination of the data interpretation procedures and the reference data needed

5. Identification of the criteria by which the quality of information can be evaluated

The topics/tasks in remote sensing include:

Elements of Photographic Systems

Principles of Photogrammetry

Visual Image Interpretation

Multispectral, Thermal , and Hyperspectral Scanning

Digital Image Interpretation and Analysis

Microwave and Lidar Sensing

Earth Resource Satellites Operating in Optical Spectrum.

The Landsat Satellite Program - which began in 1967 by NASA and US Depart-

ment of Interior as Earth Resources Technology Satellites (ERTS) – was one of the first to

map Earth’s resources. ERTS was renamed in 1975 to Landsat series (to distinguish from

the planned Seasat oceanographic satellite program). The data were acquired from Land-

sat1 to Landsat 7 missions (except the Landsat 6, because of the failure upon launch on

October 5, 1993). Different types of sensors and their combination have been included in

these missions. Among them are: Return Beam Vidicon (RBV), the Multispectral Scanner

(MSS), the Thematic Mapper ™, the Enhanced Thematic Mapper (ETM) and the En-

hanced Thematic Mapper Plus (ETM+). The Landsat 1-3 satellites had an orbit at 900 km

altitude with 18 days repeatability. The Landsat 4-5-& - 7 an orbit at 705 km altitude with

16 days repeatability. There is a joint effort from US Geological Survey (USGS) and

NASA to continue the collection of “Landsat-like” imagery. There is also an interagency

group to develop long term plan to achieve and continue technical, financial and manageri-

al stability for imaging the land (however it will not be constrained to technical capabili-

ties of current Landsat series). The US Integrated Earth Observation System (IEOS) is

USA contribution to Global Earth Observation System of Systems (GEOSS). Another

program for mapping the Earth’s resources called SPOT was initiated by French govern-

ment in 1978. SPOT is an acronym, which stands for: Systeme Pour l’Observation de la

Terre. It was developed by French space agency called CNES (Centre National d’Etudes

Spatiales). SPOT has developed into a large scale international program with ground re-

ceiving stations and data distribution centers located in more than 20 countries. It began

the new era in space remote sensing. SPOT 1,2 & 3 were launched at an altitude of 832

km and repeatability of 26 days. The sensor payload consisted of two identical High Reso-

lution Visible (HRV) imaging systems and auxiliary magnetic tape recorders. This was the

first system that included the linear array sensor and employed so called pushbroom scan-

ning techniques. It allows – among others –the full – scene stereoscopic imaging from two

different satellite tracks, over the same area. SPOT 4 (launched in 1998) had an improved

sensors, i.e. on board were: High Resolution Visible and Infrared (HRVIR) and Vegetation

instruments. SPOT 5 (launched in 2002) is equipped with two High Resolution Geometric

(HRG) instruments, a single High Resolution Stereoscopic (HRS) instruments and Vegeta-

tion instrument. is The spatial resolution of the pixels, given in meters is important for as-

sessment of the quality of received data . They vary somewhat, depending in which portion

of EM spectrum we are analyzing the images. Currently, there are ca 30 other commercial

and governmental Earth’s observation systems in space, operating in optical spectrum..





These are moderate and high resolution systems. High resolution systems, such as for ex-

ample : IKONOS, EROS-A, B, C, OrbView-3, or GeoEye1 are able to collect the data with

1- 4 m spatial resolution, and the resolution in panchromatic band approaching 0,5 m. That

is quite good, considering the altitude of these satellites, of ca 400 km (and more). Besides

USA and Europe, there are other countries, like Japan, India, Korea or Malaysia success-

fully entering “the space club”. So, we are living in interesting times, where our perception

and interpretation of the phenomena occurring on the surface of the Earth (but also above

and in inner part of our planet), will have to be revisited, and – eventually – newly inter-

preted.

Literature:

1. Lillesand T.M., Kiefer R.W., Chipman J.W., : Remote Sensing and Image Interpretation, J. Wiley &

Sons, Inc., 2007





L10 - CARTHOGRAPHY. MAP PROJECTIONS

Literacy, articulacy, numeracy & graphicacy are the basic forms of communica-

tion. As we know, 81% of our perception is acquired through visualization [seeing]. The

end results of the cartographer’s job is the map. Also maps’ derivatives such as plans, or

atlases, which are commonly used. Its an attempt to present the features of the Earth’ s

surface in 2-D, or [even more often]: 3-D . This might be seen, as reduction of spatial

properties of big surfaces and giving them the form, which enables the communica-

tion.Usually with an aid [the use] of conventional signs. Similarly to speech & writing,

maps offer us the possibility to communicate with the objects of our interest without the

necessity of direct contact with them. Its a way of monitoring & displaying the phenomena

on which [at least; to some degree/extend] men’s existence depends. In which case the

time factor plays an important role. Example of which might be : flooding, hurricanes,

changes in the coastal lines, monitoring the moisture content in the soil or air, illumination,

ground water fluctuation, depletion of reservoirs, raise of the sea level [i.e. due to global

warming], deposits of natural resources [and their exploration/excavation], communication

ways [rivers, highways, airways] These are used to interprete geographical environment.

They are the source of information which might serve as an aid in the process of decision

making. Examples of which might be the route planning for our leisure time , or rational

planning in land and urban development. Each discipline technology driven is changing

rapidly. Usually, the greater the role of technology [plays in a given specialization], the

faster its development and progress. Carthography is not an exception. It might be seen,

as the process of data acquisition and data processing, in which the following stages are

involved : 1.) source of the information { “real world”} 2.) encoder {“ conventional

sighns used in cartography”}; 3.) signal { which is created in our brain by 2-D or 3-D pat-

tern of conventional signs, presented in any given form, which enable us to understand

and interpret the presented pattern} 4.) decoder { “receptors in our vison” : eyes, or

“mind’s eyes” while creating so called “mental maps”}. As noise might be considered an-

ything which contributes to inappropriate or difficult interpretation of the attempt to pre-

sent/ display reality in a “commonly/traditionally” understood way. Examples of which

might be: inappropriate illumination, or use of conventional signs, inappropriate generali-

zation of the details [i.e. deleting the significant ones for a given/specified purpose, for ex-

ample for the defence/military reasons]. The sphere is considered as the first approxima-

tion of the Earth. An ellipsoid, or: reference ellipsoid [which implies the ellipsoid with the

specified parameters] being the next one. Therefore in cartography we are trying to project

the sphere [or: ellipsoid] on the plane [map]. There are two ways of representing the sur-

face on the plane [2]:

Direct method, where the transformation is done directly from the ellipsoid to the pro-

jection surface

Indirect method, where transformation is done first from ellipsoid to the sphere, and

next from the sphere to projection surface

As the projection surface the plane, cylinder or cone are commonly used. The atti-

tudes of projection surfaces might be: normal, transverse or oblique. Three cartographic

criteria are applied to the evaluation of map projection properties. These are:





Equidistance, which implies correct representation of distances

Conformality, which implies correct representation of shapes

Equivalency, which implies correct representation of areas

Besides the selected projection surface, the scale of the map is also important. It

characterizes the ratio between the length of the distance on a map and the length of the

same distance on the reference surface. Oversimplifying, we may say, that it is a ratio of

the distance presented on the map to the same distance in the terrain. It may be presented in

the numerical form [for example 1: 250 000], descriptive form [for example: 1 cm = 2,5

km], or graphical form [for example as the lineal with subdivisions]. Scale is often taken

as criteria to subdivide the maps into:

Large scale maps [scale greater then 1 : 200 000]

Small scale maps [scale smaller then 1 : 1 000 000]

Medium scale maps [scale between the scales of large and small scales’ maps]

The landforms and pattern of the terrain are usually presented with the contour

lines. These are the lines connecting the points at the same elevations. By knowing the cut

[separation] between the contour lines, and the distance between them, we are able to de-

termine the slope of the terrain.

Colours are also used to aid the plasticity of presented landforms. The water

[oceans, seas, rivers, streams, etc] is presented with varieties of blue colour; the plains-

with varieties of green and the hills and the mountains with varieties of brown/red. The

man made features are usually presented with conventional signs and in black.

Some grids of parallels and meridians help us to localize the point. It may be shown

as geographical coordinates [latitude and longitude], in state plane coordinate systems, or

in both.

With advancement of computers, the new discipline first called: computer assisted

cartography, and nowadays: numerical [digital] cartography was created. The terrain is

represented there in the digital form, which is suited for computer data manipulation and

reproduction of the maps. The use of computers forced us to think over [or: re-think] the

concept of the scale of the map via introduction of so called “floating” [zoomed] scales.

Also, in numerical cartography, the possibility of using wider range of colours was taken

advantage of. So called “virtual maps” were created. These are helpful to represent dynam-

ic phenomena.

In Poland there is at present so called: “System 2 000” in use, which is based on

cylindrical transverse {Gauss-Krűger} projection and GRS 80 reference ellipsoid.

Literature:

1. Robinson A., Sale R., Morrison J. : Elements of Cartography, J. Wiley & Sons, 1988

2. Richardus P, Adler R.: Map Projections , North-Holland, 1972





L11 - Definition of GIS / in polish: SIP/

This acronym [term] is used for denoting the computer aided system which enable the

collection, storing, archiving and the integration of spatial data derived [coming from]

different sources. It is used to perfom variety of operations on the stored data, such as:

data manipulation, data analysis and data display [presentation, or: visualization] im-

bebed in the specified geographical environment. The users can incorporate the specif-

ic models on which they are actually working with the data already existing [con-

tained] within the system in order to look [search] for the answers on the topics related

to:

Objects identification

Placement of the objects

Trends

Optimal paths

Relations

And models

The fundamental function of GIS is to serve as an aid [the tool] in decision making

processes

Subdivision of the Space Information Systems: Space Information System [In Polish: Sys-

tem Informacji Przestrzennej, or: SIP], System Informacji o Terenie or SIT, Geograficzny

System Innformacji or: GIS]

Note:

In English literature this subdivision practically does not exist, as anything related to

geographical location is coined with the term: Geographical Information System or GIS.

However, in Polish literature the scales of comparable maps are serving [taken] as the

criteria for that kind of subdivision

Space Information System (SIP)

this term is used to describe [encompass] the system of data acquisition, manipulation

and provision which contain space information about the specific [specified] objects

within this system, together with their relevant descriptive information. These objects

are viewed/seen/interpreted as an integral part of the space under consideration,

[Gaździcki 1990].





Land Information System (SIT, English: LIS) - [ Systemy Informacji o Terenie – (

SIT) ]

which operate [act, perform on] the original information (acquired either by direct sur-

veys or from big scale air-photos); their accuracy is comparable with/the large/big/

scale maps (i.e. scale greater then 1: 5 000, such as for example: 1: 2 000)

Geographics Information System, ( English: GIS)

which operate [act, perform on] the secondary [i.e. already manipulated, but not origi-

nal] information; their accuracy is comparable with/to middle and small scale maps

(i.e. scale 1: 10 000, and smaller such as for example: 1: 25 000)

Information Systems

SIT

The criteria which distinguishes SIT from other systems is not only its accuracy, but

also specific, details oriented data in the data base. SIT is chracterized by its institu-

tional aspects, in which the institutional aspects, [such as law, political, economical

and social] are considered. These are related to proper functioning of the entire/whole

system. Naturally, the important link – not to be overseen – are the organization-

al/structural aspects, [which mirrors the interrelation between techniacal means, range

of information and customers using/working with SIT]

According to the definition given by International Organization of Surveyors (FIG)

„SIT is the tool in the processes of decision ma king pertained to law, administration

& economy. It serves as an aid in planning & development. SIT consists of the data

base, in which spatial data pertinent to a given [specified] region are stored. SIT also

Information systems

Other (no spatial) systems Spatial information systems

Other information systems Spatial information systems

related to the earth surface

Geographic information sys-

tem

Field information system





defines [describes] the procedures and technical aspects for systematic data collec-

tion, actualization and their release”

Space Information System (SIP)

SIP provides mechanisms for the input of the spatial data, their collection, storage and

manipulation. It should ensure data unity and their integrity, thus allowing for their

preliminary verification [check].

Based on the data stored within the system it is possibile to perform different types of

analysis, which primarely rely on the spatial relation between the objects of interest

The results of the spatial analysis could be presented in descriptive (i.e. tables), or

graphiacal ways (maps, diagrams, drawings, sketches etc.). Therefore the distinct fea-

ture of the SIP is visualization of the spatial data in the desired form

Functions of the SIP

The four basic functions for the SIP systems are :

Data input

Data management

Data manipulation

Data release

GIS should give [provide] the answers to the types of questions related to:

Spatial characteristics of the objects [of interest];

Characteristic and /or evaluation of the specified areas;

Relation between these areas ;

Space-time relation , i.e. the changes occuring over specified period of time;

Transport of the people or materials along the specified routes.

Definition of GIS

GIS is an organized frame cosisting of the computer hardware, software, geographical data (spatial

and non-spatial) and the human resources (providers/executors and users) created to efficiently:

Collect ,

Store ,

Release,

Manipulate ,

Analise ,

Visualise

all geographical data .





GIS applications

GIS can be used as :

system for data manipulation (for example in order to produce maps, or 3-D visualization)

information system (for example in documentation, service )

management system ( for example in the real estate, or natural resources )

planning system (for example in construction, excavation, provision of water, gas and energy

for the users [people] or in emergency cases)

navigation system for all kinds of transportation ( i.e. over the land, see and air)

system for the data analysis ( for example while solving the environmental problems or in op-

timization processes )





L12 – SKILLS WHICH THE PROFESSIONAL SHOULD POSSES

In recent years in Poland we may observe a certain „fashion” to study Geodesy-

Geomatic. This is related to the change of the political system. The implication of which

are the development of infrastructure [with the aids from European Union] and the empha-

sis on the privatization. However few of the [potential] students realize, what the Geodesy,

Geodetic Surveying or Surveying is all about. The aim of this writing is to outline, what

skills are expected from the student and potential professional in these fields.

Generally speaking, Geodesy and Surveying are closely related to the fields of ap-

plied Mathematics. So, the knowledge of certain disciplines, such as for example: Linear

Algebra, Matrices, Vectors and Tensors, Statistics, Adjustment Computations and Com-

puter Science is required. They form – among others – the foundation on which the data

[i.e. the results of the measurements] obtained [in direct, or indirect ways] are to be ana-

lysed. The data are fed in the computers to verify mathematical models. But, the mathe-

matical models serve as only the tools to verify the physical phenomena under investiga-

tion. Examples might be: the deformation measurements, slope instabilities, inclination or

bending of the structures under the load, wind, variations in temperatures and the like.

Thus, he potential candidate is expected to:

Possess the ability to think logically

Be able to connect the reasons, with the outcome

Verify the data [i.e. reject the blunders, recognize the influence of systematical

factors and accordingly to correct the data, and justify the random errors – if these are

within acceptable tolerances]

Be able to control [check] the results in an independent way [directly, or indi-

rectly].

Analyse the data. This means, not only to feed them in the computer, but also

be able to state, if the results “make sense”

Distinguish between the errors of survey [data acquisition] and to separate

them from the results obtained with applied mathematical model

Relate the results [i.e. to interpret them] to phenomena, which they should de-

scribe [for example: the deformation measurements in Surveying Engineering]

Be able to state about implication of these results on the impact [behavior] of

the phenomena, which they describe [one-time phenomena, occurring periodically, eventu-

ally: how often, foresee the dynamic of the phenomena [i.e. the “time –factor”], and the

consequences

Suggest the solutions or implications within the specified time frame [i.e. sub-

sidence, deformations, changes in area or volume]

Know the adjacent disciplines, such as: Geotechnical Engineering, Founda-

tions, Construction, Materials, Static [in Surveying]; or: Geophysics, and in particular:

Seismology, Volcanology, Atmospheric Sciences, Remote Sensing, Sensors, Computer

Science [in Geodesy] – to mention a few

Be able to present the results of the surveys to specialists from related

fields/disciplines in a clear way.





While geodesists are spending most of time working with computers [working on variety

of projects], additional [and slightly different] skills are expected from surveyors. Among

them are:

Chose the “adequate tools” [i.e. instruments] and proper method of the survey.

There are no rules here [although some operations might be repeated], as almost each sur-

vey or enginnering project should be approached and analysed on “case by case bases”

[i.e. individually/separately]

Good orientation in the field

Organizational and managerial skills. Sometimes several surveying crews (of-

ten from different companies) are working simultaneously on the same project. Thus coor-

dination skills and good judgement of time are essential for the tasks to be accomplished

Communication skills. Often the members of survey party are coming from

other fields, or are unskilled. Thus the responsibilities of the party chief is to teach them,

how to properly use the equipment and mark the surveyed [or stake-out] points. And, after

the survey is accomplished, to present the results [sketch] and explain the people for whom

this job is done [i.e. foreman or a man responsible for the construction site] of what this

numbers, hubs, coloured paint, stakes or flagging signify

Know the flow of the traffic [“peak hours in the cities”]; or time, when it is

“the best” to perform the survey. Examples might the precise leveling, or surveys on con-

struction sites [vibrations, loosing the control points or lines of sights]

Work in adverse weather conditions [like: wind, rain, snow, fogg]; on different

elevations [multi-storeys buildings, construction of chimneys, tunnels, underground garag-

es and the like]

Know the time table of construction sites [ i.e. to be able “to foresee”, when

the surveyor will be needed]

Observe the safety rules and precautions, both in the city-traffic and on con-

struction sites; also to know and observe the local laws, rules and regulations

Work on different construction sites [sometimes to serve up to three construc-

tion sites in the same day]; and to be able to perform the different type of surveys on each

of them, using different instruments [i.e. GPS-receivers, levels, total stations]

Know the conventional signs, hand signals on construction sites, read [and

check] the engineering drawings and the blue prints

Be physically fit [carry the surveying equipment for some distances, to differ-

ent hights, clear/cut the lines of sights] and be skilled in performing minor repairs of the

vehicles





L13 - Uniqueness of Engineering and Urban Surveys

The engineering surveys are among the most demanding and challenging types of

surveys. Their uniqueness is related to accuracy and tolerances, which should be ensured.

In precise engineering surveys often there is a span between 0, 1 – 0, 01 mm. Examples

are: building of particles’s collider, alignment of power plant turbine’s axes, trans-rapid

railways, tunnels/subways or the deformation measurements. Thus, the surveyor must be

able to perform the error analysis a priori, i.e. before starting to establish the survey control

network. Then to choose the method of the survey(s). Next to choose the proper tools,

which rarely remain the “classical instruments”, like total station or precise level. And, to

establish the control in a way, which ensure the possibilities of independent check [con-

trol] and that the influence of environmental factors such as: heat, vibrations, refraction,

instabilities of the ground, or rapid changes in temperatures, to mention a few, will be

minimized . Often the space [i.e. the working area], where the surveys are to be done is

limited. Sometimes there is not enough room to set-up the tripod or instrument. The tools,

which are not “typical”, like sliding rules or micrometers sometimes have to be used. The

surveying markers are often to be “custom made”, i.e. of the special design, which will

match the applied survey method(s). Besides, the knowledge of other areas of specializa-

tion, like Theory of Elasticity, Strain and Stress Analysis, Static, Mechanics of the Materi-

als, or Geotechnical Engineering is required, [to mention just a few]. Properties of materi-

als, alloys, coefficients of their thermal expansions, distributions of the temperatures dur-

ing nights and days , or influence of atmospheric refractions and its minimalization [on the

results of surveys] is also essential. All that calls for a specialist, who is fluent not only in

methods and technics of performing the surveys, but other disciplines as well. Naturally,

all of the mentioned above, does not come out “overnight” and requires time to gain the

necessary experience and knowledge.There are usually the specialized companies [for ex-

ample Soletanche, or Hoch-Tief ] to perfrom the tunnel surveys or to carry out other highly

specialized projects. They usually either have “their own survyors”, i.e. surveyors em-

ployed by these companies, or cooperate with the surveying companies , which are able to

” provide” the surveyors fulfilling their specified condtions and/or requirements.

Urban surveying is another type of surveys, which require another [i.e. not “typi-

cal”] consideration and/or approach.

There are many factors, which influence the way, in which the surveys should be

done. Among them are:

Urbanization. The surveys in the cities are usually done either to update the ex-

isting maps [for example for the city planners] or to carry out the development in certain

parts [districts/areas] in the city. The architecture of each city is different, usually with his-

torical downtown quarter in older cities; and different traffic solutions [subways, busses,

tramways, paths for cyclists]. Thus the zones in the cities [residential, commertial, indus-

trial], the widths of the streets and types of the surface [asphalt, concrete, cobble-stones],

distribution of service lines and heights of the buildings have to be considered.

Dense population and the traffic congestion. This is especially noticeable in the

“ rush hours”, when people are hurrying up to/from work or schools





Obstruction of the lines of sights. These are caused by pedestrians walking on

sidewalks, city buses, tramways, cyclists, or parking vehicles unloading / loading the sup-

plies

Dense/congested network of underground utilities. There are sewers, pipes

made of different materials and different diamenters [like: water, gas, steam] and variety of

cables [electric, tv, telephone, optical fibre] which have to be identified and measured in

the field. Certain aid is provided by the electronic locators for underground utilities , the

satellite images and aerial photogrammetry [to identify the manholes, light poles, fire hy-

drants, etc]. However, one should not relay solely on them. Thus “in situ” verification, to

confirm the depth and the type of localized cables or pipes is necessary.

Except the GPS surveys, the elements measured are usually the angles, the distanc-

es, or combination of both. Depending on the geometry and city design, one of the follow-

ing methods is usually chosen:

Traverse

The polar method

The orthogonal method

The extension method

The resection method

Intersection of points by distance measurements

Intersection of points by angle measurements

The use of Photogrammetry is of special interest in urban areas. Terrestial Photo-

grammetry is often used to do an inventory of interiors of architectural objects, such as

churches. Or to anlyse the existing structures and/or objects such as historical monuments,

facades of historical buildings, or city halls before their renovation/restoration. Aerial Pho-

togrammetry and satellite images are helpful to identify the features of underground and

surface utilities such as the manholes, fire hydrants, traffic lights or light poles.

While performing the GPS surveys in the cities, the urban canyons have to be iden-

tified and the effect of multipath has to be accounted for [considered].

Literature:

[1] Blachut T.J., Chrzanowski A., Saastamoinen J.H.: “Urban Surveying and Mapping”, Springer, 1979





L14 - Challenges in Geodynamics1i

Within the last years Geodesy significantly contributed to the development in Geo-

dynamics. By providing the vast amount of observational data it helped to verify some

models, eventually to build the new theories. The scope of challenges in Geodynamics is

broad. According to [1], they are related to: “

Early Days of the Earth. What processes occurred within the first few hun-

dred million years of its formation that made the Earth habitable today?

Generation of Plate Tectonics from Mantle Convection. Why does plate

tectonic occur on Earth but not in other terrestrial mantles in our solar system?

Thermo-Chemical Evolution of Mantle and Core. Cooling of the Earth by

mantle convection is the pacemaker for growth and dispersal of continents, volcanism

worldwide, and solidification of the inner core

Tectonics, Water, Climate, and the Biosphere. The mantle is Earth’s largest

reservoir, sequestering and exchanging water, carbon dioxide, and other volatiles with the

surface environment

Dynamics of the Continents – Interiors, Roots, and Margins. How do the

continents, with their deep roots, ancient interiors, and deforming margins, accommodate

tectonic plate motions?

Intra-plate Volcanism – Causes and Consequences. The origins of intraplate

volcanism remain deeply controversial, especially the major long-lived, mid-plate hotspots

such as Hawaii

Earthquake Dynamics. How can geodynamics lead to better understanding of

destructive earthquakes and tsunamis?

Geology of the Core-Mantle Boundry Region. What geological processes

shape the core-mantle boundry, the most fundamental transition in the Earth’s interior?

Origin of the Earth’s Changing Magnetic Field. How does dynamo process

in the core sustain our constantly changing geomagnetic shield?

Alternate Earths. Extra –solar Planetery Interiors and their Surfaces.

Earth-sized solid planets exist outside our solar system: how do we connect astronomical

observations to their interior structure and dynamics?”

These topics are addressed to potential researchers who would like to work within

Geodesy,[ i.e. geodetical methods, observations and technics] to contribute to some of

unsresolved, or controversial issues in Geodynamics The processes which occure in the

Earth’s interior are manifested by the surface deformation. GPS and InSAR data help to

quantify the deformation fields on the surface of the Earth. Geodynamic models help to

verify the theories.The models are mainly propelled by the data. They can be interpreted on

the global, regional and local scales. We distinguish between the short term and the long

term models. There are the two groups of interpretation methods to quantify the plate mo-

tion across the broad deformation zones. These are: the block models and the continuous

models. They are mainly related to mantle convection. are The processes taking place

along the boundries of plate tectonics, the seismicity and the volcanism are of particular

interest for geodesists. Only ca 1% of all seismicity occurs away from the plate boundries.

However it is important to identify these zones, as they are occurring in usually densly

populated areas. GPS observations help to identify and verify regions which were thought





to be stable. These observations are complimented by seismic anisotropy. But when seis-

mic anisotropy is combined with laboratory data, then it helps to deduce the shear at the

depth. That leads to modified [or: new] interpretation of mantle flow beneath the continen-

tal lithosphere, the cratons and the flow within the lower crust. However, we should not

limit the scope of problems solely to plate boundries and deformation fields. The interplay

between topography changes and erosion, sedimentation and land slides is also important.

As enhanced erosion seems to control the rock uplift and exhumation. That in turn may in-

fluence tectonic responses. Weathering and also: long and short term climate changes had

an impact on evolution of the surface. Due to Global Warming effect, and – as the conse-

quence – the predicted heterogeneous sea level rise [i.e. due to collapse of the West

Anatrctic Ice Sheet] we may expect changes in the gravity, changes in Earth’s rotation and

changes in the shore line. The unresolved questions in continental dynamics remain. They

include [1, ibid]:”

What is the exact nature of deforming continental lithosphere?

What controls the rheological properties of continents?

How do cratons remain thick and undeformed over hundreds of millions of

years?

What is the role of basal tractions produced by large-scale mantle flow in

driving continental deformation?

What effect does the delamination of thickened lithosphere have on the sur-

face deformation pattern?

How is strength within the continental lithosphere distributed with depth?

What is the role of lower crustal flow in driving surface deformation?

What drives intra-plate continental deformation?

What does seismic anisotropy represent in the crustal mantle?

What is the role of dynamic topography in continental dynamics?”

In the future more than traditional models and simple geodynamic paradigms

should be done . The processes occurring in short, medium, and large spatial and temporal

scales have to be linked together. To compare the results among independent users or in-

terdisciplinary groups, standardizing input and output of benchmarked geodynamic mod-

els is necessary. The Computational Infrastructure for Geodynamics (CIG) is the step in

this direction. Earthquake physics should help to answer the frequently posed question:

where and when the major earthquakes will occure. Connecting earthquake cycles, after-

shock events and slow earthquakes should help to connect kinematic patterns of plate mo-

tion and the stress in the crust. The improved methods of data acquisition and their analy-

sis should contribute to proper interpretation of the past – to understand the present – and

to project for the future.

Literature:

1. Grand Challenges in Geodynamics, Caltech, USA, March 1, 2010, 109 pp.

i This lecture is based on workshop held In Caltech, California, USA in March 2009





L15 - Geodesy in 21st century

Geodesy-the study of Earth’s size, shape, orientation, gravity field and variation of

these quantities over time - is driven by technology. Geodetic measurements are dominated

by measurements from the space. The specialization dealing with them is called Space Ge-

odesy. Space Geodesy uses technics, which rely on precise distance or phase measure-

ments transmitted , or reflected from extraterrestrial objects. These objects might be: the

quasars [and associated with these type of measurement technic called: Very Large Base-

line Interferometry (VLBI)], the Moon [and so called: Lunar Geodesy], or artificial satel-

lites [Global Navigation Satellite Systems (GNSS); satellite systems such as GPS,

GLONASS, Galileo].Distances or phase measurements conducted between the Earth’s sur-

face and extraterrestrial objects are very precise. In some cases they are of the order of mil-

limeters – or their fractions – over distances ranging up to several thousands of kilometers.

They are easily repeated and could be obtained for almost any surface location. Moreover,

in combination with terrestrial measurements, they allow the (almost) global coverage.

Thus positioning, surface elevation, gravity field and their changes can be determined

more precisely than ever before. These types of measurements are of great social im-

portance. The rate of ice melting and associated with it sea level rise, can be determined

from the combined satellite gravity and the GPS measurements. Global sea level changes

could be estimated from the space technic called satellite altimetry [the measurements

conducted by releasing pulses towards the Earth’s surface every several milliseconds, thus

obtaining the circular ground measurements (called “footprints”) along the satellite’s

track]. This is important for monitoring the changes of the coast lines along the continents

and the islands. Depletion of aquifiers caused by exploration of natural resources [oil, gas,

mining activities] causes disturbance of natural balance in the nature. It may be manifested

as surfaces’ deformation [land subsidence, land slides] or changes in ground water level.

Each of them has an impact on conditions of human life and land use, and/or development.

They can be easily monitored with satellite technic called SAR, or: Synthetic Aperture Ra-

dar. And, even – more precisely – by comparison of pixel–by-pixel SAR phase observa-

tions of the same area to produce the Digital Elevation Models [DEM’s], or surface dis-

placement maps. This technic is called InSAR, or Interfrometric Synthetic Aperture Radar.

Space Geodesy is applied in Earth science disciplines on global, regional [continental] and

local scales. Global scale applications are related to monitoring the tectonic plate motions

[including those on the short-time geological scale]; monitoring the Earth’s rotation and its

variations, [which affect the length of the day and polar motion]; and more precise deter-

mination of the geoid. The above mentioned applications belong to set of applications

called Solid Earth (SE). Another application is the Bathymetry of ocean floor. It belongs

to so called Ocean Sciences. By using altimetry measurements combined with gravity

measurements, it is possible to detect the location of the unknown sea mounts. It is of im-

portance for navigation of submarines and investigations related to ocean bottom topogra-

phy. Application of Space Geodesy on continental [regional] scale include monitoring the

boundries of tectonic plates. Also, monitoring the deformations along them, together with

associated earthquakes and volcanic eruptions. Programs such as Plate Boundry Observa-

tory [which expanded existing GPS networks in western US] or EarthScope, allow con-

tinous monitoring [i.e. data flow]. The time scale is relatively broad. It ranges from sec-

onds to decades. They are well suited not only for monitoring tectonic plate motions and

volcanic eruptions but also for monitoring strain accumulations and pre-during-and post





seismic surface displacements related to earthquakes [earthquake deformation cycles],.

Glacial Isostatic Adjustment (GIA), formerly known as Post-Glacial Rebound is another

example of continental scale application. Due to ice caps melt, following the glacial peri-

od, the unloaded mantle undergoes the changes. Monitoring them provides information re-

lated to mantle viscosity and Earth’s dynamic oblateness [which in turn reflects the latitu-

dinal changes in mass within the Earth]. Water will be one of the most precious natural re-

sources in the future. Thus monitoring water budget on global and regional scales is im-

portant.They include – among others – monitoring of the flow of the glaciers [Cryosphere],

aquifier-system response, wetland water level changes, and river and lake water levels .

The last three applications are related to Hydrosphere. Multi-year and seasonal redistribu-

tion of water and ice mass are manifested by small, yet detectable changes in Earth’s grav-

ity field. Besides ground measurements with instruments called gravimeters, satellite mis-

sions such as GRACE and ICESat significantly contribute to better understanding of these

phenomena. GRACE stands for Gravity Recovery and Climate Experiment and the satellite

allows monitoring of large-scale regional water budget and changes in polar ice mass

changes [due to melting od an ice]. ICESat stands for Ice, Cloud and Land Elevation Satel-

lite. Together with other altimetry missions, they allow monitoring the changes of geoid

and elevation changes over ice caps. Thus, the changes of GIA induced crustal uplift can

be separated from changes induced by ice melting. That allows the better estimate of the

rate of polar ice cap melt. Signals transmitted from GNSS satellites are sensitive to water

content in the atmosphere. So, knowledge of their propagation contributes to improved es-

timation of water vapor. That has an impact on weather prediction [i.e. forecast of heavy

storm and/or hurricanes’ intensity]. GNSS signals are also sensitive to Total Electron Con-

tent (TEC) in the ionosphere. Retrival of the TEC helps to forecast the adverse space

weather. That is important in flights’ safety, the weather predictions and launching of the

satellites. On the local scales, Satellite Geodesy helps monitoring (induced by the magma

flow) deformations of volcanoes and continental rifts. InSAR combined with water level

gauges allow to monitor the changes in the coastal areas, in which tide gauges are in use.

Analysis of data from InSAR and tide gauges let us separate the regional uplift from the

sea level changes. Combination of the regional and local gravity data together with the data

obtained from the gravity satellites’ missions, allows for better estimation of soil moisture

content. These are also the tools for studying the so called surficial processes, such as land-

slides or urban and/or infrastructure subsidence. Airborne Light Detection And Scanning

(LIDAR) and Terrestial Laser Scanning (TLS) are other examples of 3-D data sets acqui-

sition to be mentioned. The recorded points are facing the sensors placed in the instrument

or platform. Their use in Geodesy, Remote Sensing, Surveying [i.e. use of the scanners in

total stations, monitoring “as built”] are likely to increase. The changes in Geodesy will be

influenced by advancements in related fields. Mathematical Modelling, Computer Science,

Mechatronics (Robotics, Sensors) are a few of them to mention and to watch for.

Literature:

1. Geodesy in the 21st Century, EOS, Vol. 90, No. 18, May 2009

Documents

MATERIAŁY DYDAKTYCZNE DO PRZEDMIOTU INTRODUCTION TO GEODESYwisge-moodle.tu.kielce.pl/file.php/1/Introduction_to_Geodesy.pdf · and Isaraeli’s commercial system EROS. All of them