Interactive Animation And Modeling By Drawing - Pedagogical Applications In Medicine

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Medicine is a discipline where visualization is an essential component of learning. However, the three-dimensional, dynamic structure of the human body poses difficult teaching challenges. There is a need for truly interactive computer tools that will enable students to create and manipulate computer models, not just watch them. We propose di erent approaches with that goal in mind. We were first interested in interactive physically-based animation of anisotropic elastic materials. One possible application scenario is an anatomy course on heart physiology where students can build interactive samples of cardiac muscular tissue. To achieve this, our model exhibits two key features. The first one is a low computational cost that results in high frame rates; the second one is an intuitive system image that ensures easy control by the user. Next, we were interested in interaction in three dimensions using two-dimensional input, either for annotating existing models, or for creating new models; taking advantage of the fact that drawing practice is still considered a fundamental learning method by some anatomy teachers in the French medical school curriculum. Our 3D drawing system has a stroke representation that enables drawing redisplay when the viewpoint changes. Moreover, this representation can be mixed freely with existing polygonal surfaces for annotation purposes. In contrast, our modeling by drawing tool uses information from both stroke geometry and the drawn image, to allow three-dimensional modeling without explicit depth specification.

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iMAGIS-GRAVIR / IMAG

Animation interactive et modélisation par le dessin

Applications pédagogiques en médecine

David Bourguignon

Doctorat de l’INPGSpécialité : modèles et instruments en médecine et biologie

Préparé au sein du laboratoire GRAVIRSous la direction de Marie-Paule Cani

M.C. Escher

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Burgeoning field

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Burgeoning field

•Biology and medicine are visual disciplines– Three-dimensional shapes

Frog tomography data

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Burgeoning field

•Biology and medicine are visual disciplines– Three-dimensional shapes– Dynamic phenomena

Dynamic imagingleft ventricle human heart

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Burgeoning field

•Biology and medicine are visual disciplines– Three-dimensional shapes– Dynamic phenomena

•Problems for teaching using real organisms– Practical availability

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Burgeoning field

•Biology and medicine are visual disciplines– Three-dimensional shapes– Dynamic phenomena

•Problems for teaching using real organisms– Practical availability– Practical feasibility

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Current solutions– Anatomical databases (images, 3D models)

http://www.netanatomy.com

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Current solutions– Anatomical databases (images, 3D models)– Multimedia documents

http://www.froguts.com

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Current solutions– Anatomical databases (images, 3D models)– Multimedia documents

http://www.froguts.com

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Current solutions– Anatomical databases (images, 3D models)– Multimedia documents

http://www.froguts.com

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Current solutions– Anatomical databases (images, 3D models)– Multimedia documents

•Drawbacks– No editing tools available

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Current solutions– Anatomical databases (images, 3D models)– Multimedia documents

•Drawbacks– No editing tools available– Teacher and students in observer role

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Need for truly interactive teaching tools– User-centered

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Need for truly interactive teaching tools– User-centered– Understand shape and function of organs

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Need for truly interactive teaching tools– User-centered– Understand shape and function of organs– Create, edit, animate models

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Need for truly interactive teaching tools

•Two interdisciplinary collaborations– MENRT research action “Beating heart”

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Need for truly interactive teaching tools

•Two interdisciplinary collaborations– MENRT research action “Beating heart”– Anatomy laboratory CHU Grenoble

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Need for truly interactive teaching tools

•Two interdisciplinary collaborations

•Two pedagogical scenarios– Physiological anatomy course

• Build interactive samples

• Experiment

iMAGIS-GRAVIR / IMAG

Information Technology in Teaching

•Need for truly interactive teaching tools

•Two interdisciplinary collaborations

•Two pedagogical scenarios– Physiological anatomy course– Structural anatomy course

• Draw or annotate

• Create or edit

iMAGIS-GRAVIR / IMAG

Our Contributions

•Part 1: Interactive physically based animation– Animating anisotropic elastic materials

[Bourguignon and Cani, EGCAS 2000]

•Part 2: Interaction in 3D using 2D input– Drawing in 3D [Bourguignon et al., EG 2001]– Modeling by drawing

iMAGIS-GRAVIR / IMAG

Our Contributions

•Part 1: Interactive physically based animation– Animating anisotropic elastic materials

[Bourguignon and Cani, EGCAS 2000]

•Part 2: Interaction in 3D using 2D input– Drawing in 3D [Bourguignon et al., EG 2001]– Modeling by drawing

iMAGIS-GRAVIR / IMAG

Motivation

•Manipulate interactive samples

Part 1

iMAGIS-GRAVIR / IMAG

Motivation

•Manipulate interactive samples

•Biological materials– Dynamics– Nonlinear elasticity– Anisotropy– Incompressibility

Part 1

Computer model ofcardiac geometry andmuscle fiber (McCulloch, UCSD)

iMAGIS-GRAVIR / IMAG

Motivation

•Manipulate interactive samples

•Biological materials– Dynamics– Nonlinear elasticity– Anisotropy– Incompressibility

Human liver (Epidaure, INRIA)

Part 1

iMAGIS-GRAVIR / IMAG

Motivation

•Manipulate interactive samples

•Biological materials

• Intuitively and efficiently

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Continuous Models– Large deformations [O’Brien and Hodgins, 1999]

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Continuous Models– Large deformations [O’Brien and Hodgins, 1999]– Multiresolution [Debunne et al., 2001]

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Continuous Models– Large deformations [O’Brien and Hodgins, 1999]– Multiresolution [Debunne et al., 2001]– Physical nonlinearities and transversal isotropy

[Picinbono et al., 2001]

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Continuous Models– Large deformations [O’Brien and Hodgins, 1999]– Multiresolution [Debunne et al., 2001]– Physical nonlinearities and transversal isotropy

[Picinbono et al., 2001]

•Problems– Incompressibility

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Continuous Models– Large deformations [O’Brien and Hodgins, 1999]– Multiresolution [Debunne et al., 2001]– Physical nonlinearities and transversal isotropy

[Picinbono et al., 2001]

•Problems– Incompressibility– Parameters setting

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Discrete Models– Large deformations

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Discrete Models– Large deformations– Physical nonlinearities [Lee et al., 1995]

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Discrete Models– Large deformations– Physical nonlinearities [Lee et al., 1995]

•Problems– No multiresolution [Debunne et al., 2001]

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Discrete Models– Large deformations– Physical nonlinearities [Lee et al., 1995]

•Problems– No multiresolution [Debunne et al., 2001]– Anisotropy [Ng and Fiume, 1997]

Part 1

iMAGIS-GRAVIR / IMAG

Previous Work

•Discrete Models– Large deformations– Physical nonlinearities [Lee et al., 1995]

•Problems– No multiresolution [Debunne et al., 2001]– Anisotropy [Ng and Fiume, 1997]– Incompressibility

Part 1

iMAGIS-GRAVIR / IMAG

Mass-Spring Systems

• Mesh geometry influences material behavior– Undesired anisotropy

– Incorrect behavior in bending

Tetrahedral mass-spring system

Part 1

iMAGIS-GRAVIR / IMAG

Mass-Spring Systems

• Mesh geometry influences material behavior– Undesired anisotropy

– Incorrect behavior in bending

Part 1

Tetrahedral mass-spring system

iMAGIS-GRAVIR / IMAG

Our Approach

•Goal– As simple and efficient as mass-spring system– Speed vs precision tradeoff– Anisotropy– Incompressibility

Part 1

iMAGIS-GRAVIR / IMAG

Our Approach

•Goal– As simple and efficient as mass-spring system– Speed vs precision tradeoff– Anisotropy– Incompressibility

•Choice– Discrete model– Uncouple forces directions and mesh geometry

[Barzel, 1992]

Part 1

iMAGIS-GRAVIR / IMAG

Our Approach

•Data: Geometry

Surface mesh

Part 1

iMAGIS-GRAVIR / IMAG

Our Approach

•Data: Geometry

Surface mesh

Part 1

Volume mesh

iMAGIS-GRAVIR / IMAG

Our Approach

•Data: Vector field

Surface mesh

Part 1

Volume mesh

Vector field

iMAGIS-GRAVIR / IMAG

Our Approach

•Elements

Surface mesh

Part 1

Volume mesh

Vector field

Barycenter

Axes of interest(mechanical characteristics)

iMAGIS-GRAVIR / IMAG

Our Approach

•Elements

Surface mesh

Part 1

Volume mesh

Vector field

Barycenter

Axes of interest(mechanical characteristics)

For each element:1. Element deformation2. Local frame deformation3. Forces applied to local frame4. Forces applied to nodes

iMAGIS-GRAVIR / IMAG

Forces Calculations

Stretch:Axial damped spring forces (each axis)

Shear:Angular spring forces(each pair of axes)

f1

I1’

I1

e1

f1’

f3

I1’

I1 e1

e3

I3

I3’f1

f1’

f3’

Part 1

iMAGIS-GRAVIR / IMAG

Volume Conservation• Soft constraint [Lee et al., 1995]

• Conserve sum of barycenter-vertices distances

fC

fB

fD

fA

Part 1

iMAGIS-GRAVIR / IMAG

Volume Conservation

•Comparison with mass-spring systems

With volume conservationforces

Mass-spring system

Without volume conservationforces

Part 1

iMAGIS-GRAVIR / IMAG

Results• Comparison with mass-spring systems

– No more undesired anisotropy

– Correct behavior in bending

Orthotropic material (as muscle fiber)Same parameters in the 3 directions

Part 1

iMAGIS-GRAVIR / IMAG

Results• Comparison with mass-spring systems

– No more undesired anisotropy

– Correct behavior in bending

Part 1

Orthotropic material (as muscle fiber)Same parameters in the 3 directions

iMAGIS-GRAVIR / IMAG

Results• Different anisotropic behaviors with same tetrahedral mesh

Horizontal

Part 1

iMAGIS-GRAVIR / IMAG

Results• Different anisotropic behaviors with same tetrahedral mesh

Diagonal

Part 1

iMAGIS-GRAVIR / IMAG

Results• Different anisotropic behaviors with same tetrahedral mesh

Part 1

Hemicircular

iMAGIS-GRAVIR / IMAG

Results• Different anisotropic behaviors with same tetrahedral mesh

Part 1

Concentric Helicoidal

iMAGIS-GRAVIR / IMAG

Results• Different anisotropic behaviors with same tetrahedral mesh

Part 1

Concentric Helicoidal (top view)

iMAGIS-GRAVIR / IMAG

Results• Different anisotropic behaviors with same tetrahedral mesh

Part 1

Random

iMAGIS-GRAVIR / IMAG

Validations

• Emerging behavior [Boux de Casson, 2000]– Define a behavior at the element level

– Measure the emerging behavior at the object level

Part 1

iMAGIS-GRAVIR / IMAG

Validations

• Emerging behaviorObject level behavior

Part 1

f1

I1’

I1

e1

f1’

Element level behavior (data points fit) +

iMAGIS-GRAVIR / IMAG

Validations

• Multiresolution behavior [Debunne, 2000]

Part 1

iMAGIS-GRAVIR / IMAG

Validations

• Multiresolution behavior [Debunne, 2000]

Mass-spring system Our model

Part 1

iMAGIS-GRAVIR / IMAG

Conclusion and Future Work

•Conclusion: Pedagogical application– Build interactive samples of biological materials

• Nonlinear, anisotropic behaviors

• Soft constraint for volume conservation

• Efficient

Part 1

iMAGIS-GRAVIR / IMAG

Conclusion and Future Work

•Conclusion: Pedagogical application– Build interactive samples of biological materials

• Nonlinear, anisotropic behaviors

• Soft constraint for volume conservation

• Efficient

– Experiment by varying model parameters• Intuitive system image [Norman, 1988]

Part 1

iMAGIS-GRAVIR / IMAG

Conclusion and Future Work

•Conclusion: Pedagogical application

•Future work: “Animated sketches”– Draw sample

Part 1

iMAGIS-GRAVIR / IMAG

Conclusion and Future Work

•Conclusion: Pedagogical application

•Future work: “Animated sketches”– Draw sample– Specify parameters by drawing

Part 1

iMAGIS-GRAVIR / IMAG

Conclusion and Future Work

•Conclusion: Pedagogical application

•Future work: “Animated sketches”– Draw sample– Specify parameters by drawing

Animate!

Part 1

iMAGIS-GRAVIR / IMAG

Our Contributions

•Part 1: Interactive physically based animation– Animating anisotropic elastic materials

[Bourguignon and Cani, EGCAS 2000]

•Part 2: Interaction in 3D using 2D input– Drawing in 3D [Bourguignon et al., EG 2001]– Modeling by drawing

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Most people draw– Writing alternative

• Faster

• More convenient

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Most people draw– Writing alternative– Minimal tool set

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Most people draw– Writing alternative– Minimal tool set– Since kindergarten

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Most people draw

•Few people sculpt– Materials difficult to handle

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Most people draw

•Few people sculpt– Materials difficult to handle– Simpler with computer ?

• Scanning

• Modeling

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Most people draw

•Few people sculpt

•Drawing application: Teaching– Example: Pr. Jean-Paul Chirossel, anatomy

laboratory CHU Grenoble

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Drawing characteristics– Visual abstraction

Human heart

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Drawing characteristics– Visual abstraction– Indication of uncertainty

Leonardo da Vinci

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Drawing characteristics– Visual abstraction– Indication of uncertainty– Limitation to single viewpoint

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Drawing characteristics– Visual abstraction– Indication of uncertainty– Limitation to single viewpoint

•Problems– Drawing with multiple viewpoints

Part 2

iMAGIS-GRAVIR / IMAG

Motivation

•Drawing characteristics– Visual abstraction– Indication of uncertainty– Limitation to single viewpoint

•Problems– Drawing with multiple viewpoints– Modeling by drawing

Part 2

iMAGIS-GRAVIR / IMAG

Our Contributions

•Part 1: Interactive physically based animation– Animating anisotropic elastic materials

[Bourguignon and Cani, EGCAS 2000]

•Part 2: Interaction in 3D using 2D input– Drawing in 3D [Bourguignon et al., EG 2001]– Modeling by drawing

Part 2.1

iMAGIS-GRAVIR / IMAG

Previous Work

•2D-to-3D drawing: 3D Strokes– Input stroke and its shadow [Cohen et al., 1999]

• 3D curves design, no drawing

Part 2.1

iMAGIS-GRAVIR / IMAG

Previous Work

•2D-to-3D drawing: 3D Strokes– Input stroke and its shadow [Cohen et al., 1999]– Deep canvas [Disney, 1999]

• Need a 3D model

Part 2.1

iMAGIS-GRAVIR / IMAG

Previous Work

•2D-to-3D drawing: 3D Strokes– Input stroke and its shadow [Cohen et al., 1999]– Deep canvas [Disney, 1999]– Billboard, terrain, etc., stroke [Cohen et al., 2000]

• Drawing modes adapted to landscaping only

Part 2.1

iMAGIS-GRAVIR / IMAG

Previous Work

•2D-to-3D drawing: 3D Strokes

•2D-to-3D drawing: 3D Objects– Reconstruction [Lipson and Shpitalni, 1996]

• No free-form drawing

Part 2.1

iMAGIS-GRAVIR / IMAG

Previous Work

•2D-to-3D drawing: 3D Strokes

•2D-to-3D drawing: 3D Objects– Reconstruction [Lipson and Shpitalni, 1996]– Sketching interface [Igarashi et al., 1999]

• Closed strokes only

Part 2.1

iMAGIS-GRAVIR / IMAG

Our Approach

•Drawing in 3D– Augment strokes to true 3D entities

• Line stroke: Space curve (view-independent)

Eye

Edgar Degas

Part 2.1

iMAGIS-GRAVIR / IMAG

Our Approach

•Drawing in 3D– Augment strokes to true 3D entities

• Line stroke: Space curve (view-independent)

• Silhouette stroke: Surface contour (view-dependent)

Back

Edgar Degas

Part 2.1

iMAGIS-GRAVIR / IMAG

Our Approach

•Drawing in 3D– Augment strokes to true 3D entities– Annotation of existing 3D models

Part 2.1

iMAGIS-GRAVIR / IMAG

Our Approach

•Drawing in 3D– Augment strokes to true 3D entities– Annotation of existing 3D models– Illustration in 3D

Part 2.1

iMAGIS-GRAVIR / IMAG

Our Approach

•Drawing in 3D

•Choices– Represent line stroke as space curve

Part 2.1

iMAGIS-GRAVIR / IMAG

Our Approach

•Drawing in 3D

•Choices– Represent line stroke as space curve– Represent silhouette stroke using local surface

• Infer local surface from user input

• New silhouette from new viewpoint

Part 2.1

iMAGIS-GRAVIR / IMAG

Silhouette Stroke

• Infer local surface from user input– Simplest: same local curvature in 3D as in 2D

Part 2.1

iMAGIS-GRAVIR / IMAG

Silhouette Stroke

• Infer local surface from user input– Simplest: same local curvature in 3D as in 2D– Modulate width as if fitting circles along curve

Part 2.1

iMAGIS-GRAVIR / IMAG

Silhouette Stroke

• Infer local surface from user input– Simplest: same local curvature in 3D as in 2D– Modulate width as if fitting circles along curve– Resulting surface

Part 2.1

iMAGIS-GRAVIR / IMAG

Silhouette Stroke

•New silhouette from new viewpoint– Approximate silhouette

Part 2.1

iMAGIS-GRAVIR / IMAG

Silhouette Stroke

•New silhouette from new viewpoint– Approximate silhouette– Represent uncertainty away from viewpoint

Part 2.1

iMAGIS-GRAVIR / IMAG

Silhouette Stroke

•New silhouette from new viewpoint– Approximate silhouette– Represent uncertainty away from viewpoint– Manage occlusion with background color

Part 2.1

iMAGIS-GRAVIR / IMAG

Interface for Drawing

•Two drawing modes– In empty space

Part 2.1

iMAGIS-GRAVIR / IMAG

Interface for Drawing

•Two drawing modes– In empty space– Relatively to other objects

Part 2.1

iMAGIS-GRAVIR / IMAG

Interface for Drawing

•Video

Part 2.1

iMAGIS-GRAVIR / IMAG

Applications

•Annotation

Part 2.1

iMAGIS-GRAVIR / IMAG

Applications

• Illustration

Part 2.1

iMAGIS-GRAVIR / IMAG

Conclusion

•System for drawing in 3D– View-dependent strokes

Part 2.1

iMAGIS-GRAVIR / IMAG

Conclusion

•System for drawing in 3D– View-dependent strokes– Useful for drawing simple scenes in 3D

Part 2.1

iMAGIS-GRAVIR / IMAG

Conclusion

•System for drawing in 3D– View-dependent strokes– Useful for drawing simple scenes in 3D– Useful for annotations

Part 2.1

iMAGIS-GRAVIR / IMAG

Conclusion

•System for drawing in 3D

•Limitations– Switching between stroke types

Part 2.1

iMAGIS-GRAVIR / IMAG

Conclusion

•System for drawing in 3D

•Limitations– Switching between stroke types– Plane positioning can be tedious

Part 2.1

iMAGIS-GRAVIR / IMAG

Our Contributions

•Part 1: Interactive physically based animation– Animating anisotropic elastic materials

[Bourguignon and Cani, EGCAS 2000]

•Part 2: Interaction in 3D using 2D input– Drawing in 3D [Bourguignon et al., EG 2001]– Modeling by drawing

Part 2.2

iMAGIS-GRAVIR / IMAG

Motivation

• Input: Just plain strokes…– Silhouette, sharp features ?– Texture, shading ?– Open, closed, self-intersecting ?

Part 2.2

iMAGIS-GRAVIR / IMAG

Motivation

• Input: Just plain strokes…

•Output: Manifold polyhedral surface

Part 2.2

iMAGIS-GRAVIR / IMAG

Motivation

• Input: Just plain strokes…

•Output: Manifold polyhedral surface

•Pen-and-paper for sculptors– Painter and sculptor shading

Michelangelo BuonarrotiRembrandt van Rijn

Part 2.2

iMAGIS-GRAVIR / IMAG

Previous Work•Painting depth as luminance [Williams, 1990]

Part 2.2

+

iMAGIS-GRAVIR / IMAG

Previous Work•Silhouette inflation [Williams, 1991]

Part 2.2

iMAGIS-GRAVIR / IMAG

Previous Work•Editing gradient by shading [van Overveld, 1996]

Part 2.2

iMAGIS-GRAVIR / IMAG

Previous Work•Bump map inference [Johnston, 2002]

Part 2.2

iMAGIS-GRAVIR / IMAG

Previous Work•Direct manipulation interface

Artisan [Alias|wavefront, 2002]

ZBrush [Pixologic, 2002]

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D

•Overview

Strokes2Ddiscontinuous

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D

•Overview

Strokes

Geometry

2Ddiscontinuous

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D

•Overview

Strokes

Geometry Constrained triangulation

2Ddiscontinuous

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D

•Overview

Strokes

Geometry Constrained triangulation

Non-convex hull

2Ddiscontinuous

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D

•Overview

Strokes

Geometry

Image

Constrained triangulation

Non-convex hull

2Ddiscontinuous

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D

•Overview

Strokes

Geometry

Image

Constrained triangulation

Non-convex hull

Height field

2Ddiscontinuous

2.5Dcontinuous

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D•Find a non-convex hull

– Original drawing (polylines)

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D•Find a non-convex hull

– Original drawing (polylines)– Constrained Delaunay triangulation

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D•Find a non-convex hull

– Original drawing (polylines)– Constrained Delaunay triangulation– Non-convex hull [Watson, 1997]

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D•Hole marks

– In comics books production

Stone #3, Avalon Studios

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D•Hole marks

– In comics books production– In our system

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D• Infer a height field

– Large features have large inflations

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D• Infer a height field

– Large features have large inflations– Use geometry information to build it

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D• Infer a height field

– Large features have large inflations– Use geometry information to build it– Use texture information to modulate it

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D• Infer a height field: First step

– Euclidean distance transform

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D• Infer a height field: First step

– Mapping to unit sphere [Oh et al., 2001]

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D• Infer a height field: First step

– Adaptive low pass filter [Williams, 1991]

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D• Infer a height field: Second step

– Use same filter for image

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D• Infer a height field: Third step

– Use previous height field as matte for image

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D• Infer a height field: Result

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D

•Fast polygonal height field approximation [Garland and Heckbert, 1995]

Part 2.2

iMAGIS-GRAVIR / IMAG

From 2D to 2.5D

•Result: Manifold polyhedral surface

Part 2.2

iMAGIS-GRAVIR / IMAG

Results

•A simple sketch of a human heart

iMAGIS-GRAVIR / IMAG

Conclusion

•System for modeling by drawing– Plain strokes as input– Manifold polyhedral surface as output– Using sculptor shading convention

Part 2.2

iMAGIS-GRAVIR / IMAG

Conclusion

•System for modeling by drawing– Plain strokes as input– Manifold polyhedral surface as output– Using sculptor shading convention

•Limited to a single viewpoint

Part 2.2

iMAGIS-GRAVIR / IMAG

Future Work

•From 2.5D to 3D: Iterative modeling process

Modeling by drawing

Changing viewpoint

Part 2.2

iMAGIS-GRAVIR / IMAG

Future Work

•Relief metaphor– From low to high relief– From painting to sculpture

Fourth century B.C.

First century B.C.

Fifteenth century

Part 2.2

iMAGIS-GRAVIR / IMAG

General Conclusion

•Animation of anisotropic material– Intuitive– Efficient

iMAGIS-GRAVIR / IMAG

General Conclusion

•Animation of anisotropic material

•Three-dimensional drawing system– Use drawing characteristics– Good geometric detail vs modeling speed tradeoff

iMAGIS-GRAVIR / IMAG

General Conclusion

•Animation of anisotropic material

•Three-dimensional drawing system

•Modeling by drawing from a single viewpoint

iMAGIS-GRAVIR / IMAG

General Future Work

•Evaluation according to ergonomics methods

•“Drawing as a front-end to everything” [Gross and Do, 1996]

iMAGIS-GRAVIR / IMAG

Merci de votre attention

iMAGIS-GRAVIR / IMAG

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