18

University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

  • Upload
    others

  • View
    1

  • Download
    0

Embed Size (px)

Citation preview

Page 1: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

������������� ����������������������������� !���#"%$'&��(�)$+*,-$/.��0�#��$����

1�2436587:9�;�</=?>�@BA82DCE9F7G7H�IKJ�L�M�NOL-PQP)RTS)J�UWV6NYX[Z6\^]:_Q\G`Bab(c8dWNYe[fgX[PFh/iQNYjQkmlonp`onpkpq8rF_os)N4t�ugd#v)U)wWV6x4yEj6z�x

{ P)q|lQ}-n8]~]����|PF]�x k { _�x a)n)x kpPWR

�������p���B�Q�)����`Q�Wr { \�rF`Qq\:`o_onph)\:`oa���ZB`okpq�\GP)`o��lDrp�)n { npkpnp`Qq�]GsK�Dn�np`��|loP�}�`�q|P�Dn�n8�Ynpkpq�\G�)n���P {��o{ PQ_BZokm\G`Ba/nm�km\Gnp`Qq { npkpPWa)`Q\:q�\GP)`+r#]Ga)P { \:q|loR��pxO�(P�}-np�Wn { NDq|lonR�P)�|q4ZB�|nm��Z6]��|lDr � n�_Bn��|k { \ � q|P { �?��P {?{ n�kpP)aW`6\Gq�\:PW`r { n��^ �¡m¢)�8P {-£p¤�¥�¦~§ �^ �¡8¢)� { rFq|lon {q|lDr�` ¨)�^ Q©m¢)�ªx���`!q|lQ\:� � r � n { }-n�\G`Qq { PQ_BZokpn/rF` r �B�o{ PQr�kml q|l�rFq�q�\:n���q|PWa)npq|lon {]:PQk�rp]�\:`Q�Wr { \�r�`Qq�_onp�|k { \ � q�\GP)`o��\:`Qq|P�]�r { aWn { PW�6«¬npkpq�_onp�|k { \ � q�\GP)`o�pxY­�lBn�R�npq|lBPQ_}-P {|® �}-nm]^]���P {� ]�r�`Dr { P)�Q«|npkpq|�¯rF`o_�lDr���Dnpnp`�Zo�|np_�}-\:q|lQ\G`�q�}-P!_Q\~�On { np`Qq{ npkpP)aW`6\Gq�\GP)`��|sQ�|q|n�R��px

° ±�²(³Y´Yµ�¶�·�¸?³O¹mµ�²

º?»�º ¼!½F¾�¿-À�Á�¿[ÂDÃYÄQ¾ÅÃY¿[ÆÁF¿ÈÇÊÉDË�ÉY½�Ì8Í?ÄÏÎ�ÉYÐ6Í4À?¿-¾�ÆW¾ÅÍ4¿Ñ�2Y9�A�3Q;mÒ!@QÓE5m9WÔp@oÕBÖY×:;8×:ÖYÕ�@oØoÙp9WÔ#A8;�Ó�58@BÚÜÛ�ÖYÒDÖY@QC�Ö ÝD×:9�C�Þ4@B×:Ö�Am;�×:;�;mÞ49F9WßD9WßKÛYÞ�;8×:ÕoÖY×~Ó�à×�Ô�36Ö�Am7:á+C�2�9�Ö�×:Ö4ßD9pâY×:ÖYÕ�Ó�ÛYÖ4ÔpAm×G@BÖY;/36589�ÛY;89Wßã=�ä-ÝB9�Ö�A82�@oÛYÕB2å×:A�×:;Ôp7:9W365A82436A3ÏAm2Y589F9ÞY2?3Q;89�Þ4365�3oßO×GÕBÚæÛ�;8×:ÖYÕ�çWè�é:è�ê#ë|ì�íQîYïDì�î?ðoè#ñòì�îOóE3QÖ4ß!êpíQô�ôpèpç|õYíQî4ðBè�î4êpè�ö:÷o÷møY×:;[ÖY9)Ôp9�;8;p3Q5má�Ó�@o55m9WÔp@oÕBÖY×:A8×:@oÖÊïDA82Y9×:Ö4ßO9pâY×GÖ�Õ�ÞY243Q;m92436;�ÛYÖDA8×:7[5m9WÔp9�ÖDA87:á!Ø?9�9�Öå367GÚ�@B;8A�9�ÖDAm×G5m9�7:áÏ×:ÕoÖ�@o589)ß�=ù|Ö Þ�5�3oÔ#A8×�Ôp9oï?A82�9/9�Ú�Þ�243Q;m×G;�@QÓ�A82�9589WÔ#@oÕoÖ�×GAm×:@oÖ ÞY5m@YÔp9WßDÛY5m9�243Q;�Ø49F9�ÖåÞ�7�3BÔp9Wß!@BÖ ÞY5m@QàßDÛ?Ôp×:ÖYÕ/5m9�7:×�3QØY7:9Ôp@o5m589�;mÞ4@BÖ4ßD9�Ö?Ôp9¯367:Õo@o5m×:A82YÚ�;�ú¬3�5m9�ÝD×G9FCæ×:;�Õo×:ÝB9�ÖÏ×:Ö ö:÷o÷mø�û�=Yüý9�ÖY9�5p3Q7:7:á�ï;mÛ4Ôm2þ3Q7:ÕB@o58×:Am2YÚ�;Ôp@oÚ�Ú�ÛYA89�×:Ö4ßO9pâY×GÖ�Õ A8@å3ÿ7G×:ÖY9)3Q5;m9W3Q5pÔ82 Am2Y58@BÛYÕo2�Am2Y9ÏÚ�@YßD9�7�Ø436;89ÞY5m@YßDÛ4Ôp×:ÖYÕ 3QÖ�×:ÖY9 � Ôp×:9�ÖDAÞY58@YÔp9F;8;�ßDÛY9�A8@K3QA8Am9�Ú�ÞYAm;A8@!ÚÏ3QApÔm2�9�Ýo9�5máåÚ�@YßD9F7�A8@ Am2Y9;pÔp9�ÖY9o=

�D×:Ö4Ôp9�Am2Y9Ï3QÞ�ÞY7:×�ÔF3QA8×:@BÖå@6Ó0ÕB9�@oÚ�9�Am58×�Ô�×:ÖDÝo3Q58×�36Ö�Am;�Am@åÔp@oÚ�Þ�ÛYA89�5�Ý�×:;m×G@BÖå×:A�2436;Ø49#àÔp@BÚ�90Ô#7G9)3Q5-2Y@QC�A82�9E×:Ö4ßD9#âO×:ÖYÕ�ÞY58@BØY7:9�ÚTÚÏ3)á�Ø49�@QÝB9�5�Ô#@oÚ�9o=)ù|ÖDÝo3Q5m×�36ÖDA8;[Þ�58@QÝD×�ßD9E;m243QÞ?9ßD9F;�Ôp5m×GÞ�A8×:@oÖY;�A82?3QA�3Q589�ÛYÖ4Ôm2436ÖYÕo9Wß%ØDá�Ý�×:9�C�Þ?@o×:ÖDAWïB3QÖ4ß%Ú�9W3Q;mÛY589�;�@6Ó�3QÖ�×:ÖDÝo3Q5m×�36ÖDAÈÔF3QÖØ?9ÏÛY;m9Wß�A8@ ×:Ö4ßO9pâ ×:Ö�Am@ Ú�@YßD9�7�;8Þ43BÔp9 3QÖ4ß 2Dá�Þ?@oAm2Y9�;m×G;m9ÏAm2Y9!ÞY589�;m9�Ö4Ôp9�@QÓ�3QÖ�@oØoÙp9)ÔpA×:Ö 3�;pÔp9�ÖY9o=ã<T589FÝ�×:9�C @QÓE;m@oÚ�9@6Ó�A82Y9�9W3Q5m7:×G9F5�3QÞ�ÞY7:×�ÔF3QA8×:@BÖ+@6Ó�×GÖDÝo3658×�3QÖDA8;�×:Ö ÝD×:;8×:@BÖ+×:;ÕB×GÝB9�ÖÏ×:Ö ö��Y÷mø8ï�@oA82�9�5�C�@o5mÒ�;�C�2�9�589×:ÖDÝo3Q5m×�3QÖDA8;�243)Ýo9�Ø?9�9�Ö�Ôp@oÚ�Þ�ÛYA89Wß+Ó�@o5�3�Ýo3Q5m×G9FA|áÏ@QÓßD×���9�589FÖ�A�ß�3QA�3�A|áDÞ49F;�3Q589�ö:÷Qï��4ïYï�÷��Yï�÷ �Dï�÷��Yï���Dï���Dï����ï���Dï�Y÷#ø8=o<�7GAm2Y@oÛ�Õo2Ï×:Ö4ßO9pâY9�;Ô�36ÖØ?90Ôp@BÚ�ÞYÛYAm9Wß×:Ö;m×:A8Û436A8×:@oÖY;ÊC�2Y9�5m9E×:ÖDÝo3Q5m×�36ÖDA8;[Ô�36ÖYÖY@oA�ö:÷ �Fø8ï�×:ÖÕB9�ÖY9�5p3Q7|ï)×:Ö�Ýo3658×�3QÖDAm;ÞY5m@QÝD×�ßO9�A82�9Ú�@o;mA�9 � Ôp×:9�ÖDA�58@BÛYA89�A8@�Am2Y9�×:5�Ôp5m9W3QAm×G@BÖ[=

��9�9�Ú�ÞY2436;8×:;89�Am243QA�×:ÖDÝo3Q5m×�36ÖDA8;�3QÖ4ß�×:Ö4ßD9pâY9�;�3Q5m9�Ö�@oA�9pâ43oÔ#A87:áÏAm2Y9;�36Ú�9�@oØoÙp9WÔ#A8;W=��589 �BÛY9FÖ�Am7:á�ïFA82Y9�×:ÖDÝo3Q5m×�3QÖDA ßO9�;�Ôp5m×:ÞYA8×:@oÖýÓ�@o5[3�;89�AÊ@QÓYCE@B587�ß�Ó�9W36A8ÛY5m9�;-×G;[3�7:×G;mA�@QÓYÖDÛYÚ�Ø49�5m;Am243QA-Ô�3QÖØ?9�ÛY;m9Wß�ßD×:589WÔpAm7:á�Am@�Ó�@o5mÚ 3�Ú/Û�7GAm×~à ßD×:Ú�9�Ö�;8×:@oÖ4367W×:Ö4ßO9pâ[=�Ñ�2Y×:;[×:;ÊA858Û�9-Ó�@o5ÊÞY7�3QÖY9367GÕB9�ØY5p3Q×�Ô!×:ÖDÝo3Q58×�36Ö�Am;W=���@QC�9�Ýo9�5)ï�×:ÖDÝo3Q58×�36Ö�AÏßO9�;�Ôp5m×:ÞYA8@B58;å36589�;8@BÚ�9�A8×:Ú�9�;Kç�ì:óQî��)ë��Dô�è#çÔp@BÚ�ÞYÛYAm9Wß%Ó�58@BÚÜ3+ê��6î4íQîYì�ê��6é� �ô��"!�è(C�2Y×�Ô82 Ô�36ÖYÖY@BA�Ø49�ÛY;m9Wß!3Q;�3QÖ!×:Ö4ßD9#âÏA8@Ï3�Ú�@OßO9�7Ø436;89oïDØ�ÛYAEÚ�ÛY;mAEØ?9�ÚÏ3QÞYÞ?9Wß�Am@/3�Ö�Û�Ú�9�58×�Ô�Ýo367:ÛY9�ÛY;m×:ÖYÕ/3�Ô82�@o;89FÖ+Am5�36ÖY;|Ó�@B58Ú Þ�58×:@o5�A8@

Page 2: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

×:Ö4ßD9pâY×:ÖYÕ?=�äÊâ436Ú�ÞY7:9�;�@QÓ[Am2Y×:;EÔ�36;893Q5m9�A82�9�ÞY7�3QÖ�9�ÔpÛY58ÝB9�;8×:ÕoÖ436A8ÛY5m9�;�×GÖ ö��Dï�����ï����òø ïB3QÖ4ß��# ;8×:ÕoÖ?3QA8Û�589�;�Ó�@B5�@oØoÙp9)ÔpA8;�Ôp@oÖDA�36×:ÖY×:ÖYÕ/Þ�7�36ÖY9�;�@6Ó�ØY×:7�3QAm9�5�367�;8áDÚ�Ú�9�A85má ö����Fø8=

º?»%$ &('�¾Å¿�À)&(Í?À4ÉDÆ�*�ÉDÄ,+�Í[Ð6Ã-/.0*-Ã1�É3254-ÉY½

1�9�5mA�3Q×:Ö�Ôp58×:Am9�58×�36�BÛ43Q7:×~Ó�á!A82Y9�ÛYAm×G7:×:A|á!@QÓ03%;82436Þ49ÏßO9�;�Ôp5m×:ÞYA8@B5 7Ê;8@oÚ�9�@QÓ�A82Y9�;m9ÏÔp58×:Am9�58×�33Q5m9�7:×G;mA89Wß�×:Ö ö��Dï?÷ �Fø8=��DÛYØ�;89 �BÛY9�ÖDA�A8@3QÖ�9FÝo3Q7:Û43QAm×:@oÖ@6Óã3�C�@o58ÒD×:ÖYÕ�589)Ôp@oÕBÖY×:A8×:@oÖ�;8áD;8Am9�Ú@oÖ�9 589W367:×G;m9�;ÏAm243QA�Am@o7:9�5p3QÖ4Ôp9�A8@�@YÔ�Ôp7:ÛY;m×G@BÖ ×G;�ÖY9WÔp9F;8;�3658áD=���×:A82Y@BÛYA/Am2Y×:;ÏC�9 Ô�3QÖYÖ�@oA2Y@BÞ49�Ó�@o5 36Ö�á Ú�9W36;8ÛY5m9å@6Ó¯5m9�7:×�3QØY×:7:×:A|á�ÛYÖ4ßD9�5K3�;8Þ?9WÔpAm58ÛYÚ @6Ó/ÝD×G9FC�×GÖ�ÕþÔp@BÖ4ßD×:A8×:@oÖ�;W=ù|Ö4ßD9FÞ49�Ö?ßD9�Ö4Ôp9�Ó�5m@oÚ @YÔ�Ôp7:ÛY;8×:@BÖþÔ�36Ö Ø?9+3oÔm2Y×:9�ÝB9Wß�C�2Y9�Ö éGí)ê��6é�@o5�çWè8!�ì:98é:íWê��Qé~ï�5�36A82Y9F5A82?3QÖ óòé:í�;��Qé~ï�ßO9�;�Ôp5m×:ÞYA8@B58;+36589!ÛY;m9Wß�=�ù|Ö�@oÛY5ÏÔ#@oÖDA89pâYA)ï-CE9 ßD9�<?ÖY9!7G@YÔ�367�Ú�9W3Q;mÛY589F;�A8@Ø?9�@oØY;m9�58Ýo36ØY7:9¯36A�3�;8×:ÖYÕB7G9�Þ4@B×GÖDA)ï 36Ö4ß�;89�Ú�×~à|7G@YÔ�367[Am@+Ø?9�Ú�9W3Q;mÛY589Wß�36A�3�ÖDÛYÚ�Ø49�5�@6ÓÞY5m@)âO×:ÚÏ3674Þ?@o×:ÖDA8;�Ôp@QÝo9F58×:ÖYÕ�3�;8ÚÏ367G7?ÞY5m@oÞ?@o58Am×:@oÖÏ@6ÓÈ36ÖÏ@oØoÙ#9WÔpA�Ø4@BÛYÖ4ßY3658áD=��@QC�9�Ýo9�5)ïD×:ÖA82�9/;m9 �BÛY9�7�Am2Y9�589�×:;�7G×:AmA87:9�ÖY9�9WßKAm@+ßD×:;8Am×:ÖYÕoÛY×:;m2+Ø?9�A|C�9�9�Ö�Am2Y9�;89�A|C�@ÏÔ�36;89�;�7�Ø4@BA82KC�×:7G7Ø?9/ßD9�;pÔp58×:Ø?9Wßå36;éGí)ê��Qé^=

ù|Ö!ÞY5p3oÔpAm×�Ô#9ÚÏ3QÖDáÏ@6Ó�Am2Y9×:ÖDÝo3Q58×�36Ö�Am;E5m9�Þ?@o58Am9Wß�×GÖ!Am2Y9�7G×:Am9�5�36A8ÛY5m9/3Q5m97:@OÔF3Q7|=��@QC�à9�ÝB9�5Wï�;8@BÚ�9!Ø�á�Ö43QAmÛY589K3Q589�Õo7:@oØ4367036Ö4ß�;8@ 36589 ÖY@BA�589�7:9�Ýo36ÖDA�A8@�A82�9åßD×:;�ÔpÛ�;8;8×:@BÖ�×:ÖA82�9Þ43QÞ?9�5�=ò=>-5m9WßD@BÚ�×GÖ?3QÖDAE9#â�36Ú�ÞY7:9�;�@QÓ-A82Y9F;89/36589�?DÚ�@BÚ�9�ÖDAEØ436;89Wß�Ú�9�Am2Y@YßD;�öG÷Bï���Fø@7×:;8@6à¬Þ?9�58×:Ú�9�Am58×�Ô�Ú�9W36;8ÛY5m9�;�ö ��Fø@7Y3QÖ4ß�Õo7:@BØ43Q7A<4A8Am×:ÖYÕ�@QÓ�3Q7:Õo9�Ø�5�3Q×�Ô�ÔpÛY58ÝB9�;ö:÷ �DïB���Fø8=

Ñ-@o7:9�5p3QÖ4Ô#9/Am@ @YÔ�Ôp7:ÛY;8×:@BÖ Ô�3QÖ�Ø?9Ï3oÔm2Y×:9�ÝB9WßK@oÖY7:á ×~ÓEAm2Y9�5m9+3Q5m9Ï3!7�3Q5mÕo9�Ö�Û�Ú/Ø?9�5@6Ó;82?3QÞ?9�ÔpÛY9�;�;8ÞY5m9W3oß�3658@BÛYÖ4ß�A82Y9�Ø?@oÛYÖ?ßY3Q5má@QÓ[3QÖ�@oØoÙp9)ÔpA�ú�Am2Y×:;-ÞY589�ÝB9�ÖDA8;�A82Y9�Þ?3QA82�@o7:@oÕ6à×�Ô�3Q7�Ô�36;89�@6Óã3ý;8×:ÖYÕo7:9�ßD9F;�Ôp5m×GÞ�A8@o5�Ø?9�×:ÖYÕ@YÔ�Ôp7:Û4ßD9)ßYû�=DÑ�2Y×:;-×:;�ô�èpðC��î?ð��Qî?ê8D�3QÖ4ßýÓ�5m@oÚ 3QÖDáÖY@B58ÚÏ3Q7�ÝD×:9�C�Þ4@B×:Ö�A�@oÖY9�CE@BÛY7�ßK@oØY;m9�58ÝB9ÿ3ÿÖ�Û�Ú/Ø?9�5�@QÓ�ßD9�;pÔp58×:ÞYAm@o5m; ú�ÕB9�ÖY9�5p3Q7:7:áåÚ�@B589A82?3QÖ @BÖY9Wû�=�Ñ�2Y9�ÞY58@BØY7:9�Ú 9�Ö4Ôp@BÛYÖDA89�5m9Wß ×:Ö!ÛY;m×GÖ�ÕÏ3�7G@YÔ�367[Ú�9W36;8ÛY5m9�Ó�@B5�589WÔp@BÕoÖY×:Am×G@BÖÏ×:;A82?3QAE367GAm2Y@oÛ�Õo2�×GA-ÚÏ3)á2DáDÞ?@oA82�9�;8×:;89�Am2Y9�Þ�589�;m9�Ö4Ôp9�@QÓ[3QÖ�@oØoÙ#9WÔpA�×GÖ�3�;�Ôp9FÖY9oïD;8Û?Ô82Ï3ý2�áBàÞ?@oA82�9�;8×:;�Ó�5m9 �BÛY9�ÖDA87:áÏáD×:9�7�ßD;�@oÖY7:á�3Þ?@D@o5�9�;8Am×:ÚÏ3QA89�@QÓ-A82Y9�@oØoÙp9WÔ#A�Þ4@B;89�ú�Am2Y×:;E×:;�;82Y@QC�Ö7�3QAm9�5E×:ÖE<4ÕBÛY589/�oßYûF=F��ÛY5mA82Y9�5mÚ�@o5m9oïo7:@YÔ�367 ßD9F;�Ôp5m×GÞ�A8×:@oÖY;�A89FÖ4ß�Am@/áD×:9�7�ßÝB9�58á�;mÞ43Q5m;89�589FÞDà589F;89�ÖDA�36A8×:@oÖ�;�@6Ó�@oØoÙp9WÔ#A8;�A82436A�ßD@�ÖY@oA�Þ�58@QÝD×�ßD9/3�;mÛ � Ôp×:9�ÖDA87:á�58×�Ôm2åßD9�;pÔp58×:ÞYAm×G@BÖå@6Ó�A82Y9Õo9F@oÚ�9�Am58á!@QÓ�3QÖÏ@BØoÙp9WÔpA�Ó�@o5�ÚÏ36ÖDá�A�3Q;mÒD;W=

ù|Ö�A82Y×:;�Þ436Þ49�5�C�9!ÞY589F;89�ÖDA+3ÿÓ�5p3QÚ�9�C�@o5mÒ�A82436A�9�Ö43QØ�7G9F;�7G@YÔ�367�×:Ö�Ýo3658×�3QÖDA�Ó�9W3QAmÛY589Õo5m@oÛYÞ�;�A8@�Ø49�A8×:9Wß�A8@BÕo9�Am2Y9�5�×:ÖDA8@ÕB7G@BØ43Q7�;8A85mÛ4ÔpAmÛY589�;)=HG�7:Am×GÚÏ36A89�7:áAm2Y9�;m9ÞY58@QÝD×�ßD9�Ôp@oÚ�àÞY7:9�Am9 @oØoÙp9)ÔpA ßD9�;�Ô#58×:ÞYA8×:@BÖY;ÏÛY;m9pÓ�ÛY7�Ó�@B5�589WÔ#@oÕoÖ�×GAm×:@oÖ[=-Ñ�2Y9�ÞY58@YÔp9�;m; @QÓ�Ú�9�58ÕB×:ÖYÕ�7:@OÔF3Q7@oØoÙ#9WÔpAÏ2DáDÞ?@oA82�9�;89�;�A8@BÕo9�Am2Y9�5Ï×:;�ÒDÖY@QC�Ö�3Q;JIFDpõYí)ëKIOè#ç#ì�ç�è#ñ)ë èFîDç�ì�íQî�ö����)ø8ï-3QÖ4ß Ô�36Ö Ø49Ôp@BÚ�Þ43Q5m9Wß Am@ÏAm2Y9+êFé^ìML��Yè� WíQô8!,�)ë|ì�í6î�ÞY58@YÔp9F;8;�@QÓON(@o7:7:9�;�3QÖ4ß 1�36×:Ö+ö��)ø8=?äÊâYA89�ÖY;m×:@oÖå3BÔmàA8Û?3Q7:7:áÏÞY5m@QÝ�×�ßD9F;�3ÏÔ#@oÚ�ÞY7:9�Am92Y×:9�5�365�Ôm2Y×�Ô�367�@BØoÙp9WÔpA�ßD9�;pÔp58×:ÞYAm×G@BÖå;m×:Ú�×G7�365EAm@ÏA82?3QA�×:ÖDA85m@QàßDÛ4Ô#9Wß!ØDá+ä-AmA8×:ÖYÕB9�5�ö��Fø8=

Ñ�2Y9�5m9�;8A�@QÓ�Am2Y×:;�Þ43QÞ?9�5�×:;�@B58Õ�36ÖY×:;89Wß�3Q;�Ó�@B7G7:@QC�;�?o;m9WÔpA8×:@BÖP��ØY5m×:9�Q4á+ßO9�;�Ôp5m×:Ø49�;�A82Y93Q5pÔm2Y×:A89WÔpAmÛY589�@QÓ�A82Y9�×:Ö4ßD9pâKØ43Q;m9WßK589WÔ#@oÕoÖ�×GAm×:@oÖK;8áD;8Am9�Ú ÛY;89WßKAm@!A89�;mAA82Y9�2DáDÞ?@oA82�9�;8×:;9pâYA89FÖY;8×:@oÖK3Q7:Õo@B58×:A82YÚ�;�7o;m9WÔpAm×G@BÖR�ÞY5m@QÝD×�ßO9�;�;8Þ?9WÔp×�< Ô�9#â�36Ú�ÞY7:9�;�@QÓ-A82Y9367GÕB@o5m×GAm2YÚ�;�3QÞDàÞY7:×:9Wß�A8@�589W367�ßY36A�37?3QÖ4ßJ��;mÛYÕoÕB9�;8Am;�;8@BÚ�9C�3)á�;�×:Ö!C�2Y×�Ôm2!A82Y9/Ô#ÛY585m9�ÖDA�Ú�9FA82Y@YßD;�Ô�3QÖØ?99pâYA89�Ö?ßD9Wß!Am@�@oA82�9�5�@BØoÙp9WÔpA�Ôp7�36;8;89F;W=S ��P�}-np�)n { ND\:`oa)np`Q\GP)Zo���|npa)R�n�`Qq8rFq�\GP)`Ïq|npkmlo`Q\:TQZonp��k�rF`ÏPF��q|n�`�s)\:nm]G_Ïrý]GPQk�rp]�\:`Q�Wr { \�rF`Qq�Zo��\G`Bar�_Bnp�|k { \ � q�\:PW`�`oP { Rrp]~]Gs { np�|n { �Wnp_���P { a�]:PW�Drp]�Zo�|n)x

Page 3: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

U VXWZY�±D²\[\]-´Y¹^]�²(³ ±D²�¶ZY0_�¹8²Z`baJ]�´A]�¶�¹@`\cÑ�2Y×:;�Þ436Þ49F5Ï589F7�36A89�;�A8@ 3KÞY7�3QÖ4365/@BØoÙp9WÔpA!589)Ôp@oÕBÖY×:A8×:@oÖ ;8áD;mA89�Ú ï�Ô�3Q7:7:9Wßed[äf�gù@��ïEßD9#à;pÔp58×:Ø?9Wß!×:Ö+ßD9FA�3Q×:7Ê×GÖ ö����Fø =dÊäf��ù@�%243Q;�Am2Y9�Ó�5p3QÚ�9�C�@o5mÒ�;82Y@QC�Ö!×:Ö,<4ÕBÛY589�÷�?÷o=hg Ç[À?ÉRi�É�Æ)ÉYÐQÆ)¾�Í?¿kj 9)ßDÕo9�7-Ôm243Q×:ÖY;�36589�9pâYA85p3oÔpAm9Wß�Ó�5m@oÚ Õo5m9�áD;�Ô�367G9�×GÚÏ36Õo9�;�ÛY;m×GÖ�Õ¯31�36ÖYÖDá�9WßDÕo9ßD9FA89WÔpAm@o5ö:÷ lFø8=��D×:ÖYÕo7:9�9WßDÕo9F7[ßD58@BÞ4@BÛYA8;�Ø?9�A|C�9�9�ÖåÔm2436×GÖ�;036589�Þ43QApÔm2Y9WßÛYÞ!Am@�@QÝo9�5pÔp@oÚ�9�Ú�×:ÖY@o5�;89FÕoÚ�9�ÖDA�36A8×:@oÖ�Ó¬36×:7GÛ�589�;)=

�Y=hm É�Ã�Æ 4-ÄQÉ g Ë�Æ)ÄQÃ4ÐQÆ)¾�Í?¿�j Þ?@o×:ÖDA8;WïD7:×:ÖY9�;�36Ö4ß!Ôp@oÖ�×�Ô#;�3Q589�9pâYAm5�3oÔ#A89WßÿÓ�58@BÚ A82�9�9)ßDÕo9�7Ôm2436×GÖ�;È36Ö4ß�Õo58@BÛYÞ?9Wß�3oÔ�Ô#@o5�ßO×GÖ�Õ�Am@�Ôp5m×:A89�5m×�3ýÕo×:Ýo9�Ö�×GÖ ö���ï�÷��Yï"���òøYA8@�Ó�@o5mÚT3Q7:Õo9FØY5�36×�ÔÓ�9)3QA8Û�589�Õo58@BÛYÞY;)=�>Ê@o58Am×:@oÖY;Ê@QÓ ÔpÛ�58Ýo9�Ø?9�A|CE9F9�ÖÏÔpÛY5mÝo9�ØY×:A�36ÖYÕo9FÖ�Am;�36589�3Q7:;8@�9pâYA85�3BÔpA89)ßú|Ô�3Q7:7:9WßJn Ô#ÛY58ÝB9�;�û�3QÖ?ßÏÛ�;89Wß�Ó�@o5�A82Y95m9WÔp@BÕoÖY×:A8×:@BÖ+@6Ó�Ú�@B589�Õo9�Ö�9�5�367�Þ�7�36ÖY9ÔpÛY5mÝo9;mA858Û?ÔpA8ÛY5m9�;W=

�Y= Á�¿ÊÂDÃYÄQ¾�ÃY¿ÊÆ m Í?Ä"o�ÃYÆW¾ÅÍ4¿�j ×:ÖDÝo3Q5m×�3QÖDA0ßO9�;�Ôp5m×:ÞYA8×:@oÖ�;ý36589Ú�9)3Q;8Û�589Wß�Ó�@o5�Am2Y9�Ó�9)3QA8Û�589ÕB58@oÛ�ÞY;W=

�4= Á�¿�ÇÊÉDË�¾�¿-ÀHj ×:Ö4ßO9pâY9�;Ï3Q5m9+Ôp@BÚ�ÞYÛYA89)ßKÓ�5m@oÚ Am2Y9ÏÚ�9W36;8ÛY5m9Wß�×:Ö�Ýo3658×�3QÖDAm;Wï�Am2Y9�;89 36589ÛY;m9Wß�A8@�×:Ö4ßD9#â/Ú�@YßD9�7:;[×:Ö�3�Ú�ÛY7:A8×~à8ßD×:Ú�9�ÖY;m×G@BÖ43Q7Q×:Ö4ßO9pâ/;8Þ?3oÔp9o=Bä�3oÔm2�A8×:Ú�9036Ö/×:Ö4ßO9pâ<4Ö?ßD;�3�ÚÏ3QApÔ82 3�2Dá�Þ?@oAm2Y9�;m×G;�×:;�Ôp589W36A89Wß+Ó�@o5�Am2Y9�×GÖ?ßD9pâY9Wß!@BØoÙp9WÔpA)=

�Y=hp '01�Í?Æ *-ÉY½F¾�½kq ÉDÄQÀ?¾�¿-ÀHj ×:Ö4ßD×:ÝD×�ßDÛ4367W2DáDÞ4@BA82Y9F;89�;ÊÓ�5m@oÚ A82Y9�;p3QÚ�9-@oØoÙ#9WÔpA�36589EÔ#@oÚ�àØY×:ÖY9)ß�A8@�Ôp589W36A893�;m×GÖ�Õo7:9�2Dá�Þ?@oAm2Y9�;m×G;�Ôp@B58589F;8Þ?@oÖ4ßD×:ÖYÕ�Am@7�3Q5mÕo9�5�Ú�@YßD9F7 36Ö4ß�×:ÚÏ3QÕB9Ó�9)3QA8Û�589�Õo58@BÛYÞY;)=4Ñ�2�×G;�;mA89�ÞK×:;rIFDpõYí)ëKIOè#ç�ì:çÏèpñ)ë èFîDç�ì�í6î+36Ö4ß!ÞY5m@QÝ�×�ßD9F;�A82�9¯ßD9FA�3Q×:7-@QÓAm2Y×:;�Þ43QÞ?9�5W=

Y=�s ÉDÄQ¾:tEÐQÃYÆ)¾�Í?¿�j Ñ�2Y9!589WÔp@BÕoÖY×:Am×G@BÖ�2Dá�Þ?@oAm2Y9�;m9�;+36589ÏÝB9�58×�<49)ß�ØDá�Ø43oÔmÒBà|ÞY58@WÙ#9WÔpA8×:@BÖ[ïAm2Y@oÛYÕB2 ×:Ö!ÞY5�3BÔpA8×�Ôp9oï�36Ö�á!@6Ó(3�ÖDÛYÚ�Ø?9�5�@6ÓÈ@BA82Y9F5�ÝB9�58×�< ÔF3QA8×:@BÖ+Ú�9FA82Y@YßD;�Ôp@oÛY7�ß!Ø?9ÛY;m9Wß�=

u våµ\cxw�¹m²�¹m²(`zy/µ�¸0]f{Evå·ZYH|äÊâYAm9�Ö4ßD×:ÖYÕ!7:@YÔ�3Q7ÊÓ�9W36A8ÛY5m9�Õo5m@oÛYÞY;�9�Ö?3QØY7:9�;Ú�@B589�589�7:×�3QØ�7G9�589)Ôp@oÕBÖY×:A8×:@oÖ Am2Y58@BÛYÕo2K2Y×:9�5 à365�Ôm2Y×�Ô�3Q7�@BØoÙp9WÔpA�ßD9�;pÔp58×:ÞYAm×G@BÖ[=Yä-;m;89�ÖDA8×�367G7:áDïDA82Y9�5"}@o7:9�@QÓ�9#âOAm9�ÖY;m×G@BÖ ×:;EAm@ÏÔp@oÚ�ØY×:ÖY9�7G@YÔ�367Ó�9)3QA8Û�589Ôp@oÖ~<4ÕoÛY5p3QAm×G@BÖY;�×GÖDAm@/ÕB58@oÛ�ÞY;�A82436A036589�ÛY;m9Wß!A8@�ßD5m×GÝB9�3�2Y×:ÕB2Y9�5�7G9FÝo9�7�@6Ó�589)Ôp@oÕ6àÖY×:Am×G@BÖ[=DÑ�2Y9�Ôp@oÚ�ØY×:Ö436A8×:@oÖ�@QÓEAm2Y9�Ó�9W36A8ÛY5m9�;×:;�3oÔm2Y×:9�ÝB9Wß�A82Y5m@oÛYÕB2 A82Y9�9pâYÞY7:@o×:Ap3QA8×:@BÖÏ@QÓ×:ÖDÝo3Q5m×�36Ö4Ôp9Ø?9�A|C�9�9�Ö�A82Y9!Ôp@oÖ�<?ÕoÛY5p3QA8×:@BÖY;Wï�Am2Y9�×:ÖDÝo3Q58×�36Ö�Am;�Ó�@B58Ú�9Wß�Ø?9�A|CE9F9�Ö Am2Y9ÏÔp@oÖOà<4ÕBÛY5�36A8×:@oÖ�;036589/Ô�367:7G9)ßr�Wí6ì�îDë�ì�î�"�Qô�ìM�6îDë�ç#=

äÊâYA89FÖY;8×:@oÖÏÔF3QÖ�Ø?9�ÛYÖ4ßD9�5m;8Am@�@Yß%Ø49�AmA89�5�C�2�9�Ö�@oÖY9�5m9W3Q7:×:;89F;�A82436A�×:A�@YÔ�ÔpÛY5m;036A-ÚÏ3QÖDá;mA�3QÕB9�;�A82Y5m@oÛYÕB2Y@oÛYA�A82�9Ï589)Ôp@oÕBÖY×:A8×:@oÖ�ÞY58@YÔp9�;m; 7(A82Y9�7G@QC�9�;mA/7:9�ÝB9�7E@YÔ�Ô#ÛY58;!ßDÛY58×:ÖYÕ�;89�Õ6àÚ�9�ÖDAp3QA8×:@BÖå3QÖ4ß�Õo5m@oÛYÞ�×GÖ�Õ4=Yù|Ö�×GAm×�3Q7:7:áÏA82�9�×GÖ�ÞYÛYA�A8@ 3�5m9WÔp@BÕoÖY×:A8×:@BÖå;má�;mA89�Ú ×:;3�;m9�A@QÓ9WßOÕo9�7-Þ?@o×:ÖDA8;W=0�Ê×:58;mAWï?;89�ÕBÚ�9�ÖDA�36A8×:@oÖ 9#âOÞ�7G@B×:A8;�Am2Y9�ÞY58@BÞ49�5mA|á @QÓEÔp@B7:7G×:ÖY9)3Q58×:A|á�ú�C�2Y×�Ôm2å×:;×:ÖDÝo3Q5m×�36ÖDA�Û�Ö4ßD9�5�ÞY58@WÙ#9WÔpA8×:@BÖ4û�A8@KÕo5m@oÛYÞ�9WßDÕo9F7G;�×:ÖDA8@K7:×:ÖY9�; 7-Am2Y9!Ýo3Q7:ÛY9�@QÓý36Ö ×:ÖDÝo3Q5m×^à36Ö�AýÓ�@o5/Ô#@o7:7:×GÖ�9W3Q5m×GA|á�×G;�Ø?@�@B7:9W3QÖ ú�9�×:A82Y9�5�3�;89�A�@QÓ�Þ?@o×:ÖDA8;×:;�Ôp@o7:7:×:ÖY9W365Wï�@B5×:;/ÖY@BAWï-3QA7:9W36;8A�ÛYÞÏAm@¯36ÖÏ9�5m58@o5�Am2Y589F;82Y@B7�ß�û�=���Am2Y9�5�×:ÖDÝo3Q58×�36Ö�Am;E3Q5m93Q7:;8@Û�;89Wß%Ó�@B5E;m9�ÕoÚ�9�ÖDAp3QA8×:@BÖH?Am2Y9�ÞY589F;89�5mÝo3QA8×:@BÖ�@QÓ0Ôp@BÖY×�Ô�;89WÔ#A8×:@oÖY;�7[×:Ö4Ô#×�ßO9�Ö4Ôp9Ï36Ö4ßKA�36ÖYÕo9�Ö?Ôpá�=ã<�Ó�Am9�5;89FÕoÚ�9�ÖDA�36A8×:@oÖAm2Y9�Am@oÒo9FÖY;�ÛY;89)ß�Ó�@o5�589WÔp@BÕoÖY×:Am×G@BÖ�Ø49)Ôp@oÚ�9�7:×:ÖY9�;WïYÔ#@oÖY×�Ôp;)ïD9�A�ÔQ=:ïD×:ÖY;mA89W3Bß�@QÓ-A82Y9�@o5m×GÕB×:Ö43Q79WßOÕo9�7:;W=6Ñ�2Y9�;89�Ó�9W36A8ÛY5m9�;E3Q5m9�A82Y9FÖ�Õo58@BÛYÞ?9Wß�×:Ö�Am@�2Y×:ÕB2Y9�5�@B5�ßD9�5�Ôp@oÖ�<?ÕoÛY5p3QA8×:@BÖY;�ú�;8Û?Ô82Ï36;ÕB58@oÛ�ÞY;�@QÓf<4ÝB97:×GÖ�9�;�û�ÛY;8×:ÖYÕ�×:ÖDÝo3Q5m×�36ÖDA8;�A82436A�A�36Òo95m9W3Q7ÊÖDÛYÚ/Ø?9�5�Ýo3Q7:ÛY9�;��o=B��áDÞ4@BA82Y9F;8×:;� ��` �o{ rFk�q�\:kpn�}�n�Rrps�R�n�rF�|Z { n�\G`Q�Wr { \�rF`Qq|��q|l�rFq�q8r ® n�kpP)R � ]Gnph��Wr#]GZonp�px

Page 4: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

Image

Edgels

Features

Invariant Indexes

Hypotheses

Joint Hypotheses

Results

Library

RECOGN

T

ONLibrary Formation

AC

U

S

T

ON

I

I

I

Q

FeatureExtraction

Formation

Hypothesis

Verification

Invariant

Merging

IndexingI

I

DetectionEdge

�f�:�?�"���0�B�(�/�^� ¦~£0¦:¥�� � ¤�¥�¤8����¤^� ¢ £ ¢ �4¦ ��¤ � ¦%�D¤8�0���D¤/�Q¤8� ¢ ¦ � £ ¢"� ¤ ¨ ¦:��¤��/¦:�,���D¤h��¤^�"���

9pâYA89FÖY;8×:@oÖ�A�36Òo9�;�A82Y×:;�@BÖY9�;8Ap3QÕB9�Ó�ÛY5mA82Y9F5EØDá�Ôp@oÚ�ØY×:ÖY×:ÖYÕ�ÕB58@BÛYÞY;�@QÓ[3Q7:Õo9�Ø�5�3Q×�Ô(Ó�9)3QA8Û�589�;)ï@o5ßD×���9�589FÖ�A�n ÔpÛY58ÝB9�;WïÊ×:ÖDA8@ÏÚ�@B589�Ôp@oÚ�Þ�7G9#âÿÕB58@BÛYÞY;W=?Ñ�2Y9�C�2�@o7:9@QÓ�A82Y×:;�ÞY58@YÔp9F;8;×:;;82�@QC�Ö+×:ÖJ<4ÕBÛY589r�Y=

Ñ�2Y9�589�;mAÏ@6Ó�A82Y×:;�;89WÔpAm×:@oÖ�ßD9�;pÔp58×:Ø?9�;ÏÚ�@B589 ßD9�Ap3Q×:7E2�@QC 2Dá�Þ?@oAm2Y9�;m×G;�9#âOAm9�ÖY;m×G@BÖ ×:;3oÔm2Y×:9�ÝB9Wß�Ó�@B50367:Õo9�ØY5p3Q×�Ô�×:Ö�Ýo3658×�3QÖDAm;E3QÖ4ßJn ÔpÛY5mÝo9�;)=

�ã»�º �/-�ÃY¿-ÉX��-�À4É��-ÄQÃY¾�Ð%Á�¿[ÂDÃYÄQ¾ÅÃY¿[ÆQ½>-7�3QÖ?3Q5�@oØoÙp9)ÔpA8;�Ôp@oÖDAp3Q×:ÖY×:ÖYÕ+367:Õo9�ØY5p3Q×�ÔýÓ�9W3QAmÛY589F;¯36589ÏßD9�;pÔp58×:Ø?9Wß�ØDá Am2Y9�Ó�@B7G7:@QC�×:ÖYÕ�×:ÖDàÝo3Q5m×�3QÖDA�Ó�9W3QAmÛY589ÕB58@BÛYÞY; ?

 ¢¡ = ?Y3�Þ436×:5E@6ÓÈÞ?@o×:ÖDA8;�3QÖ?ß+3�Þ?3Q×:5E@6Ó�7:×:ÖY9�;�ú�@oÖY9�×:ÖDÝo3Q58×�36Ö�A�Ýo3Q7:ÛY9)û�= ¢¡ � ?Y3�Þ436×:5E@6Ó(Ô#@oÖY×�Ôp;�ú�A|CE@�×:ÖDÝo3Q5m×�36ÖDA�Ýo3Q7:ÛY9�;pû�= ¢¡¤£ ?Y3�Ôp@BÖY×�Ô�3QÖ4ß!3�Þ43Q×:5�@QÓ-7:×GÖ�9�;�ú�@BÖY9�×GÖDÝo3658×�3QÖDA�Ýo367GÛ�9Wû�= ¢¡¤¥ ?�<4ÝB9�7G×:ÖY9F;�ú�A|C�@�×GÖDÝo3658×�3QÖDA�Ýo367GÛ�9�;�ûF=

Page 5: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

d:

c:

b:

a:

e:

Verification

Higher level combination

configs of:p pointsq lines

r conics n concavities

y

x

�f�:�?�8¦Y� ���D¤ � ¤ ¡8 8¨ ��¦:��¦   ��� �� �¡ ¤p£8£§  )�:�^ "¨ £ ¢ ��©B¥ © ¤ ��  § � ¤8��¤ � £È¦:� ¢ �D¦:¤ ��¢"��¡ ��ª «¬ ¢�­�¡8  ���D¤ ¡ ��¤^�¤^� ¨ ¤ ��¡ � ¢ ¦%�B£ ¢"� ¤�¤@�"� ��¢Q¡ ��¤^�0§ ��  ¥®���D¤�¦:¥ ¢�¨ ¤�¯0¬ ©�­ ¤^� ¨ ¤ � £ ¢"� ¤ ¨"��  ©¤��¤@�Z�  8¨ ¤����D¤ � ©6£�¦:� ¨ ¦:��� ¢"� ¦^§¢ ���:£�£�© ¡ � ¢ £ ¡8 )�:� ¦:�D¤ ¢"� ¦%�°ª�±[¤8� ¡ ��±\�   §  "� ¥²�   ¦:���:£^± � ¦:�D¤p£@± ¡8  �D¦ ¡ £ ¢ ���r³ ¡ © � ��¤p£^¯�¬ ¡´­ ���D¤p£p¤¢"� ¤/���D¤8� ¨"��  ©���¤^�r©Q£p¦:� ¨ £°��¤ ¡ ¦ µ ¡ ¦%��� ¢"� ¦ ¢ �F�0� ¢)� ©o¤p£k�  �¨ ¦:��¤ �^ �¡m¢)� ¦:��� ¢"� ¦ ¢ �����ª��   ���D¤p£�¤#£�¯¶¬´� ­�D¦ ¨ �D¤ �- "� �Q¤ � ¦:��� ¢"� ¦ ¢ ���:£ ¢"� ¤0§  "� ¥�¤^� © ¤8� ¨ ¤m¤8�·���D¤�¦%�D¦:��¦ ¢)� §p¤ ¢ ��© � ¤ ¨C��  ©¤�Y£k�  �¨ ¦:��¤ �^¢"�:¨ ¤ � §p¤ ¢ §��© � ¤ ¡8  ��µ ¨ © ��¢ ��¦   �Q£^¯¸¬|¤ ­¢ §��Ť �E¢ ¬��   £8£�¦ ©p� ª�¹�¤ �� �­ �F©B¥ © ¤ ��  §   ���D¤ ��� ¤8�F¤ � £O���D¤�¥   �Q¤ � ¦:¥ ¢�¨ ¤¡m "�@� ¤p£��   ���Q¤8� ¡ ¤�¦~£�¤8� ¢)� © ¢ ��¤@� © ª/��¤ � ¦ µ ¡8¢ �Ŧ   ���

Page 6: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

��ÓýÔp@BÛY58;m9Ï@BÖY9+Ôp@BÛY7�ßKA�36Òo9Ï3QÖDáK;8ÛY×:Ap3QØY7:9ÏÔp@BÚ/ØY×:Ö436A8×:@oÖK@QÓ�Þ?@o×:ÖDA8;)ï�7:×:ÖY9�;�3QÖ4ß�Ôp@BÖY×�Ôp;C�×:A82Ï3�;mÛ � Ôp×:9�ÖDA�ÖDÛYÚ�Ø49F5�@QÓ[ßD9�ÕB589�9�;�@6Ó4Ó�589�9WßO@oÚÜ36Ö4ß/ßO9�58×:Ýo9�@oAm2Y9�5�×:ÖDÝo3Q5m×�36ÖDA[Ó�9W3QAmÛY589Õo5m@oÛYÞ�;WïYØ�ÛYA�A82Y9F;89/36589Am2Y9�@oÖY9�;�CE9�243)ÝB9�ÛY;89Wß%Ó�@B5�589WÔ#@oÕoÖ�×GAm×:@oÖ[=

º�@o58ÚÏ367:7Gá�5m9WÔp@BÕoÖY×:A8×:@BÖ�ÞY58@YÔp9F9WßD; ØDá»<?Ö4ßD×:ÖYÕ�Ó�9W3QAmÛY589 ÕB58@BÛYÞY;�Ó�58@BÚ 36ÖDá @QÓ�A82Y93QØ?@QÝo9�Ó�@oÛY5Ôp7�3Q;m;89�;)ï�Ôp@oÚ�Þ�ÛYA8×:ÖYÕ!A82�9�×:5×:Ö�Ýo3658×�3QÖDAm;ý36Ö4ß�ÛY;8×:ÖYÕ Am2Y9�;m9ÏA8@�×GÖ?ßD9pâ�×GÖDAm@ÿ3Ú�@YßD9�7Ê7G×:ØY5p3Q5má�=Y>�9�;8ÛY7:Am×GÖ�Õ�2�áDÞ?@oAm2Y9�;89F;ý36589ÝB9�58×�<49)ß!ØDá+ßD9�Am9�58Ú�×:ÖY×:ÖYÕ�@BA82Y9F5�Ú�@YßD9�7ÊA8@×:ÚÏ3QÕB9�Ó�9W3QAmÛY589/Ô#@o585m9�;8Þ?@oÖ?ßD9�Ö4Ôp9F;W=f��@QC�9�Ýo9�5)ï4ßDÛ�9A8@�589WßDÛ�Ö4ßY3QÖ?Ôpá!CE9�Ó�589 �BÛY9�ÖDAm7Gá�<4Ö4ßÚ�@o5m9�A82436ÖÏ@oÖ�9�Ó�9W36A8ÛY5m9�Õo58@BÛYÞ!×:ÖÏ3;pÔp9�ÖY9Am243QA�2DáDÞ?@oA82�9�;8×:;89F;�3;m×GÖ�Õo7:9�@BØoÙp9WÔpA)=YÑ�2Y9�;m9×:Ö4ßD×:ÝD×�ßDÛ43Q7Ê2Dá�Þ?@oAm2Y9�;m9�;;82�@oÛY7�ß�Ø49�Ôp@oÚ�ØY×:ÖY9Wß�ÞY5m×G@B5�Am@+5m9WÔp@BÕoÖY×:A8×:@BÖ A8@!Õo×:ÝB9/3�5m×�Ôm2Y9F5@oØoÙ#9WÔpA�ßD9�;pÔp58×:ÞYAm×:@oÖ[=Bº�@oAm9�A82436A0ßD5p3)C�×:ÖYÕ/3�Ôp@oÖ4Ô#7GÛ�;8×:@oÖ!A82?3QA�Ú/ÛY7:Am×GÞ�7G9�2DáDÞ?@oA82�9�;89�;�Ó�@o53�;8×:ÖYÕB7:9�Ú�@YßD9�7Ê×GÖ!3�;�Ôp9FÖY9/Ôp@B58589F;8Þ?@oÖ4ß�A8@�A82Y9�ÞY589�;m9�Ö4Ôp9�@QÓ�3�;8×:ÖYÕB7G9�@oØoÙp9)ÔpA�Ôp@BÛY7�ß�Ø49Ó¬367G;m9�ßDÛ�9�Am@/Ú�ÛY7:A8×:ÞY7:9�@BØoÙp9WÔpA�×:ÖY;mA�3QÖ?Ôp9�;�×:ÖÏAm2Y9�;�Ôp9�Ö�9o=?<�;�35m9�;8ÛY7:A�@6Ó�A82�×G;)ïD9pâYA89�Ö�;8×:@oÖ;82�@oÛY7�ß�ÖY@oA�9#âOÞ�7G@B×:A03�ÝB@oA8×:ÖYÕ�;�Ôm2Y9FÚ�9;8Û4Ôm2 3Q;�Am243QA�Û�;89Wß!ØDá6d[3QÚÏß�3QÖ[ï�èpë(�Qé�¼�ö:÷8�)ø8=

Ñ�C�@�×GÖ?ßD×:Ý�×�ßDÛ?3Q7o2DáDÞ?@oA82�9�;89�;�Ô�36Ö�Ø49�Ôp@BÚ/Ø�×GÖ�9Wß×~Ó�;8Am58Û4ÔpAmÛY589F;�Ø49�A|C�9�9�Ö�A82Y9�ÕB58@BÛYÞY;9pâY×:;8A�Am243QA�3Q5m9�ÞY5m9�;89�5mÝo9WßÿØ�á�Þ�58@WÙp9)ÔpA8×:@oÖÊ=où|Ö6d[äf��ù@�ãïDA82Y9�3oÔpAmÛ43Q7�ÞY5m@oÞ?9�58A|á�9#âOÞ�7G@B×:A89Wß×:;ÏAm2Y9 Ô#@oÖY;m×G;mA89�Ö?Ôpáæ@6Ó/A8@BÞ4@B7:@oÕoá�Ø49FA|CE9�9FÖæAm2Y9å×:ÖDÝo3Q5m×�3QÖDAÓ�9W3QAmÛY589KÕo5m@oÛYÞY;�7(Ó�@o5�A82Y×:;A8@�Ø?9+3BÔm2Y×:9�Ýo9Wß�Am2Y9!Õo58@BÛYÞY;�Ú�ÛY;8A�Ø?9 íC�òèFô�é:�põoõ?ì�îDó!ú¬Ô�Ó�=-A82Y9!@QÝB9�587�3QÞ�ÞY×:ÖYÕå3QÖ?ß Ö�@oÖDà@QÝo9F587�3QÞYÞ�×GÖ�Õ�;mÛYØDà|Þ43Q5mAE;mA85p3QA89FÕoá�×GÖ ö��òøÅûF=���@o5-9pâ43QÚ�ÞY7:9oïBÔp@oÖY;m×�ßD9�5�A82Y5m9�9�Ó�9)3QA8Û�589�ÕB58@BÛYÞY;×:ÖÏ3�;�Ô#9�ÖY9�Am243QA�×:Ö4ßD9pâ�A82�9�;�3QÚ�9�Ú�@YßD9F7 36Ö4ß�Ôp589)3QA89�2Dá�Þ?@oAm2Y9�;m9�;(½E¾8ï�¿fÀ3ÁÃÂBÄ�ÅCÄ�Æ�Ç�ú�;m9�9<4ÕBÛY589r�oûF=où|Ö�A82Y×:;�Ô�3Q;m95½,ÈÔ#@o585m9�;8Þ?@oÖ?ßD;�Am@/3QÖ�×GÖDÝo3658×�3QÖDA-@QÓ[A|áDÞ?9 ¡ � ïY3QÖ4ß,½,É�3QÖ?ßʽ,ËA8@�A|áDÞ?9 ¡ £ =B½ È 3QÖ?ß̽ É 36589Ôp@BÚ�Þ43QAm×GØ�7G9�3Q;�Am2Y9Ôp@o5m589�;mÞ4@BÖ4ßD9�Ö4Ô#9�@QÓ�Ú�@YßD9F7[A8@�×:ÚÏ3QÕB9Ó�9W36A8ÛY5m9�;�×:;ÛYÖY×��BÛY9Ï36Ö4ß�×:;ÕB×GÝB9�Ö�ØDá)Á"Í = ?\Î = Ä�Í � ?ÏÎ � Ä + = ? - = Ä + � ? - � Ç�=H��@QCE9FÝo9�5)ï½ É 36Ö4ßX½ Ë 36589�×:Ö4Ôp@BÚ�Þ43QAm×GØ�7G9�3Q;�A82Y9�A|C�@ Ôp@o5m589�;mÞ4@BÖ4ßD9�Ö?Ôp9�;6Á + = ? - = Ä + � ? - � Ç�3QÖ4ßÁ +�Ð ? - = Ä + = ? - � Ç/Ô�3QÖ�ÖY@oA�Ø?9�;�3QAm×:;�<49Wßÿ;8×:Ú/Û�7GAp3QÖY9F@oÛY;m7GáD=äÊâ436Ú�ÞY7:9�;�@QÓ-A82Y×:;�Ó�@B58Ú @6ÓÈ9#âOAm9�ÖY;m×G@BÖå3Q5m9ßD9�Ú�@oÖ�;8A85p3QAm9Wß!×:ÖJ<4ÕoÛY5m9/��C�2Y9�589�Ú/ÛY7~àA8×:ÞY7:92DáDÞ?@oA82�9�;89�;36589ÛY;m9Wß�A8@�589)Ôp@oÕBÖY×:;89�A82Y92�×GÕB2Y7:×:Õo2DA89Wß�@BØoÙp9WÔpAm;W=?Ñ�2Y9�ÞY58@YÔp9�;m;Ô�3QÖØ?9589�Þ?9W36A89Wß!Ø?9�A|C�9�9�Ö Am2Y9�2Y×:Õo2Y9F5�@o5�ßO9�5�×:Ö�Ýo3658×�3QÖDA�ÕB58@BÛYÞY;�3QÖ?ßÏ@BA82Y9F5�×GÖ?ßD×:Ý�×�ßDÛ?3Q7?2�áBàÞ?@oA82�9�;89�;)=�ù|Ö!A82Y×:;�C�3)áÏC�9/Ô�36ÖÏÓ�@o58Ú 9pâYA89�Ö4ßO9Wß 2DáDÞ?@oA82�9�;89�;Ôp@BÖDA�3Q×:ÖY×:ÖYÕ�3QÖDá�Ö�Û�Ú/Ø?9�5@QÓ�×:Ö4ßD×:ÝD×�ßDÛ43Q7B2Dá�Þ?@oAm2Y9�;m9�; 7B9pâ43QÚ�ÞY7:9�;-@6Ó4A82Y5m9�9�2DáDÞ4@BA82Y9�;m9�;�Ø49�×:ÖYÕÔp@BÚ/Ø�×GÖ�9Wß3Q5m9�Õo×:Ýo9FÖ×:ÖJ<4ÕoÛY5m9�;5��3QÖ?ßÌ�=

Ñ�2Y9�;82�@o58A à Ô#@oÚ�×:ÖYÕ�@6Ó4A82�×G;-Ú�9�Am2Y@Yß@6Ó49pâYA89FÖY;8×:@oÖ�@YÔ�Ô#ÛY58;�C�2�9�Ö/Am2Y9�Ó�9W36A8ÛY5m9EÕB58@BÛYÞY;3Q5m9/Ö�@oA�@QÝB9�587�36ÞYÞY×:ÖYÕ4ïD;m2Y@oÛ�7�ßÿA82Y×:;�2?3QÞYÞ?9�ÖY;�A82�9/Am@oÞ?@o7:@oÕB×G9F;�@QÓEAm2Y9/ßD×���9�589�ÖDA�Ó�9W3QAmÛY589Õo5m@oÛYÞ�;+Ø?9WÔp@BÚ�9 ×:Ö4ßD9�Þ?9�Ö4ßO9�ÖDAå3QÖ4ß ;8@ Am2Y9�5m9å×:;ÏÖ�@ Þ?@o;8;m×:ØY×:7G×:A|á�@6Ó¯3 Ôp@BÖDA85�3BßD×�ÔpA8×:@BÖ@YÔ�ÔpÛY5m58×:ÖYÕ?=-Ñ�2Y×:;×:;�@QÝB9�5�Ô#@oÚ�9ÏAm2Y@oÛ�Õo2 3%Ó�ÛY5mA82Y9�5�ÛY;m9Ï@QÓ�Þ�58@WÙp9)ÔpA8×:Ýo9�×:ÖDÝo3Q5m×�3QÖDA8;�A82?3QAÛY;mÛ43Q7:7:á ÞY5m@QÝD×�ßO9�;Ï3KÚ/Û?Ô82 ;mA858@BÖYÕo9F5ÏA89F;8AÏ@6ÓA82Y9 Ôp@BÚ�Þ43QAm×GØ�×G7:×:A|áK@QÓA82Y9�2�áDÞ?@oAm2Y9�;89F;A82?3QÖþ3BÔm2Y×:9�Ýo9WßKAm2Y58@BÛYÕo2�A8@BÞ4@B7G@BÕoáD=?ù|Ö�ÞY5�3BÔpA8×�Ôp9oï-Ö�@oA@BÖY7:á 36589+367:Õo9�ØY5p3Q×�Ô�×:ÖDÝo3Q58×�36Ö�Am;Ú�9W36;8ÛY5m9Wß�C�×:A82�×GÖK;8×:ÖYÕB7:9�Ó�9W3QAmÛY589�ÕB58@BÛYÞY;WïÊØYÛYAýÓ�@o7:7:@QC�×:ÖYÕ�×:Ö4ßD9pâY×:ÖYÕ4ï?@BA82Y9�5�3Q7:ÕB9�ØY5�36×�Ô×:ÖDÝo3Q58×�36Ö�Am;036589Ôp@BÚ�ÞYÛYA89)ß!Ø49FA|CE9�9FÖ Þ43Q×:5m;�@QÓ�ÕB58@BÛYÞY;W=

Ñ�2Y×:;�Ú�@B589!Õo9�Ö�9�5�367�Ó�@B58Ú @QÓ�9#âOAm9�ÖY;m×G@BÖ�×:;ÏßD9�Ú�@BÖY;8Am5�3QAm9Wßg×GÖÑ<4ÕoÛ�589X��=k��9W3QAmÛY589Õo5m@oÛYÞ�; à 3QÖ?ß � ×:Öå3�;pÔp9�ÖY9!3Q5m9Ó�@BÛYÖ4ß!Am2Y58@BÛYÕo2K×:Ö4ßD9pâY×:ÖYÕ�A8@+Ô#@o585m9�;8Þ?@oÖ?ßKA8@!Ú�@YßD9�7Õo5m@oÛYÞ�; � 3QÖ?ßXÒ úÅÓ�58@BÚ A82�9�;�3QÚ�9�Ú�@YßD9F7�ûF=Hº�@BA89�Am243QA�A82�9ÏÔp@o5m589�;mÞ4@BÖ4ßD9�Ö4Ô#9 ×:;�Ö�@oAÙpÛY;mA à ? � 3QÖ4ß � ?hÒÏï(ØYÛYAÏ×:; à ¾6? � ¾/3QÖ4ß � ¾6?OÒ�¾8ï�¿JÀÓÁ�÷�Ä Ô�Ô Ô�Ä���ÇKú�×:Ö4ßD9#âO×:ÖYÕÞY5m@QÝ�×�ßD9F;¯3KÔp@o5m589�;mÞ4@BÖ4ßD9�Ö?Ôp9 Ø?9�A|CE9F9�Ö A82Y9�×GÖ?ßD×:Ý�×�ßDÛ?3Q7-Ó�9)3QA8Û�589�;Ï36;CE9F7G7�3Q;�Ø?9�A|CE9F9�ÖA82�9+ÕB58@BÛYÞY;�ûF=�ù�Ó Ã 3QÖ?ß � Ôp@BÚ�9�Ó�5m@oÚ Am2Y9!;�3QÚ�9�@oØoÙp9)ÔpA�×:Ö A82�9+;pÔp9�ÖY9�5�3QAm2Y9�5�Am243QÖÓ�5m@oÚ ßD×�� 9F589�ÖDA�×GÖ�;8A�36Ö4Ôp9�;�@QÓ�Am2Y9Ï;p3QÚ�9�Ú�@YßD9�7|ï�Am2Y9�5m9+3Q5m9Ï@BA82Y9�5�A89F;8A8;�@QÓ�ÕB9�@oÚ�9FA858×�Ô

Page 7: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

c.

ModelImage

l

c1 c

2

2

1l

L

1C LC

L

L

1L2

2

3

4

5

a. b.

C : c , C : c C : c , L : l , L : l

C : c , L : l , L : l1 1 5

1 1 1 1 1 1 1 1 2 2

1 1 2

�f�:�?�8ÕY�HÖ £p¦:� ¨ò� ¤(��¦:¤ ¨K  § ¢ �  Q©�× ¤ ¡ �تW¦:¤ � �)£h� ¨� �� ¦%�D¤p£(¬:Ù S ¢ ���(Ù � ­/¢ ���r� ¨� �¡8  �D¦ ¡ £Ú¬°Û S ¢ ���Û � ­ �Z�F�D¤,� ¨�  �Q¦ ÜE¤ � ¤8���H��ª´�   ���D¤p£p¤m£�¦%�»¬ ¢�­�¢ ���R¬ ©�­�¢"� ¤ ¡8  �B£�¦~£���¤8��� ¢ £ý¦:� ©8  ��� ¡8¢ £p¤p£r���D¤¡m "�@� ¤p£��   ���Q¤8� ¡ ¤(Ý SßÞ Û S ¦~£Ï¥ ¢ �Q¤ ¢ ��� ¢)�:� ���D¤   ���D¤ ��¡8 "�@� ¤p£°�   ���Q¤8� ¡ ¤8£ ¢"� ¤Ï¦:���Q¤K��¤8���Q¤8�����à� "¨ ¤8��¤ � ±���ª´�   ���D¤#£�¤p£r¬ ©�­Ï¢ ���X¬ ¡�­Ï¢"� ¤6�   � ¡m  �B£�¦~£���¤��F� ¨ ¦%��� ¤ ¢Q¡ �   ���D¤ �¢ £,���D¤ � ¤Ï¦~£,���D¤¡m  �F� ��¢ �Q¦ ¡ ��¦   �B£Há8â S Þ Ù S�ã â � Þ Ù ��äæå á¤âØç Þ Ù SÃã â S Þ Ù � ä �

Page 8: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

� �

� è�f�:�?�8é?� ���D¤ �^ F¡@ê £�� � ¦ ê ¤ � � �^¢ ��¤Z�   ���D¤ � ¤�§��   §/���D¤�£ ¡ ¤8�D¤�¦~£ � ¤ ¡m 8¨ �D¦~£�¤^�r©Q£p¦%� ¨ � ¨�  �Q¦ Ü�¤ � ¤��F���¦~£�¦ ©p� ¤0µf��¤ � ¦:��¤Ø§p¤ ¢ ��© � ¤ ¨"��  ©��Y£��æ���D¤p£p¤ ¢"� ¤k�D¦ ¨ � � ¦ ¨ ����¤^��¦:�ʬ ©´­�¢ ���·¬ ¡�­ ± ¢ ��� ¡8  © � �¤ ¢Q¡ � © ¤©Q£p¤@��¦%���Q¤K�D¤8���Q¤���� � ª/�  Ê� ¤ ¡m 8¨ �D¦~£�¤r���D¤  Q©�× ¤ ¡ �°� à� "¨ ¤8��¤ � ± ¢ ¥Z© ¡ � © ¤8����¤ � ©��F�Q¤ � £�� ¢ �F�)¦:� ¨  §���D¤�£ ¡ ¤���¤�¦~£ ¨Q¢ ¦:�D¤@� ¨ �D¤8�,���D¤h� ¨�  ��ª´�   ���D¤p£p¤p£ ¢"� ¤ ¡m  ¥ © ¦:�D¤@�Ï� � ¦  "� �   ��¤ � ¦ µ ¡8¢ ��¦   �·¬´� ­ �

Ôp@BÖY;8×:;8Am9�Ö4Ôpá�A82436A¯ÔF3QÖ Ø?9+36ÞYÞY7:×:9Wß�=H��@o5�9pâ43QÚ�ÞY7:9Ï3QÖDáKÞY58@)Ùp9WÔpAm×GÝB9!×GÖDÝo3658×�3QÖDA�Ó�@o5�A82Y9Ó�9W36A8ÛY5m9�;EÁ à = Ä Ã � Ä Ã £ Ä Ã ¥ Ä � = Ç/;82�@oÛY7�ß�ÚÏ3QApÔ82 ú�Ú�@YßDÛY7:@�ÖY@B×G;m9Wû�Am243QA�@BÖ A82�9Ú�@YßD9�7ÊÓ�@o5Á � = Ä � � Ä � £ Ä � ¥ Ä�Ò = ÇD=ù|ÖKÞY5�3BÔpA8×�Ôp9Bï[Am2Y9ÏÔp@oÖ�;8×:;8Am9�Ö4Ôpá�@6ÓEA|CE@!×:Ö4ßD×:ÝD×�ßDÛ4367�2DáDÞ?@oA82�9�;89�;�×:;�A89�;mA89Wß Ø�áKÔp@oÚ�àÞYÛYAm×:ÖYÕ!×GÖDÝo3658×�3QÖDA8;�Ø49FA|CE9�9FÖþ3QÖDá!@QÓ�A82�9ÏÔp@oÚ�ØY×:Ö43QAm×:@oÖY;�@QÓEAm2Y9�Ó�9W36A8ÛY5m9�;×:Ö Ã 3QÖ?ß � ï3QÖ?ß Ôp@oÚ�Þ?3Q58×:ÖYÕ�A82�9�ÚÜAm@Ï×:ÖDÝo3Q5m×�36ÖDA8;�Ôp@oÚ�ÞYÛ�A89Wß%Ó�@B5 � 3QÖ?ßÌÒ ú�A82�9Ú�@YßD9�7[×:ÖDÝo3Q5m×�3QÖDAÝo3Q7:ÛY9F;/Ô�3QÖ�Ø?9�ÞY5m9WÔp@oÚ�Þ�ÛYA89Wß�3QÖ4ßK;mA8@B589WßK×:Ö 3�7:@�@BÒBà¬ÛYÞKA�36ØY7:9Wû�=غ�@oAm9�A82436A@oÖ�9ÏÔ�3QÖÓ�@B58Ú @BÖY7:á�A|CE9�7:ÝB9�×:Ö4ßD9�Þ?9�Ö4ßO9�ÖDA�ÞY5m@WÙp9WÔpAm×:Ýo9×:ÖDÝo3Q5m×�36ÖDA8;-Ó�5m@oÚÜ3�;89FA�@QÓ�Am9�Ö!Þ4@B×:Ö�Am;�ú�ÛY; à×:ÖYÕÏAm2Y9�Ôp@oÛYÖDAm×GÖ�Õ+3Q5mÕoÛYÚ�9FÖ�A�@QÓEö�Fø�û�ï�3QÖ?ß!;8@!A82�9¯Ôp@BÚ�Þ43Q5m×:;8@oÖ�;�;82�@oÛY7�ß!Ø?9/@QÝB9�5�;8Û4Ôm23QÖ!×:Ö4ßD9FÞ49�Ö?ßD9�ÖDA�;m9�A £ =ë ­�lon { nEr { n-��\Gq|Z�rFq�\GP)`o�ã\G`�}�l6\Gk8l�`oP�R�P { n-\G`B_on � n�`B_onp`Qq �o{ PF«¬npkpq�\G�)n-\:`Q�Wr { \�r�`Qq|�Êk�r�`��Dn�R�n�rpc�|Z { np_��Dnpq�}-npnp`�r � r#\ { P��YkpP)`"ì�a)Z { rFq�\GP)`o�Êq|l�rF`�lDrp�Wn�r#] { n�rF_os��Dnpnp`�ZB�|n�_���P { \:`o_onph)\:`oaBxòjQZ � c� P)�|n-}-n�lDrp�)nEr��|npq�PF�Y��\Gh � P�\:`Qq|�?��P { R�np_�\:`Qq|PEq�}-PEP��)n { ]�r �o� \G`oa�ìD�Wn � PF\G`Qq[kpP)`"ìDaWZ { r�q�\:PW`B�pxíoP { n�rFk8l��|npq[PF��ì��)n � P�\:`Qq|��R�n�rF�|Z { n�q�}-P �o{ P�«|npkpq�\G�)n-\G`Q�)r { \�r�`Qq|�Ïî�q|lon�RrFh)\GR�ZBR � PW�|��\:�Q]:n¤ïr�`B_�\G`B_onph�q|P�aF\G�)nER�PQ_Bn8]YlQs � P)q|lonp�|np��ðoq|lQZo��r�q|P)q8rp]YPF�Y��PWZ { \G`B_on � np`o_onp`Qq-\:`Q�Wr { \�rF`Qq|��lDrp�)n��npnp`!Zo�|np_���P { \G`B_onph)\G`Baox[t(P�}�NYkpPWR � Zoq|n�\:`Q�Wr { \�r�`Qq|����P { q|lon�«|PF\G`Qq�kpPW`Cì�a)Z { rFq�\GP)` P���q|lBn

Page 9: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

� �

��f�:�?�8ñY� � ¨�  Q©�× ¤ ¡ �:£ ¢"� ¤ � ¤ ¡8 8¨ ��¦~£p¤@�h©Q£p¦:� ¨ ���D¤B§p¤ ¢ ��© � ¤p£-¦:�ò¬ ©�­(¨ �D¦ ¡ �\§  "� ¥ó��� � ¤8¤�¦:���Q¦%�F¦%�"© ¢)���ª´�   ���D¤p£p¤m£Ã§  "� ¤ ¢Q¡ �  Q©°× ¤ ¡ ��� Ö §���¤ � ¤@�"��¤��o£p¦   ��±Q£p¦:� ¨ò� ¤¸��ª´�   ���D¤#£�¤p£ ¢"� ¤ ¡8� ¤ ¢ ��¤^��§  "� ¤ ¢Q¡ �  Q©�× ¤ ¡ ���� ¢ � ¢"� ¤(�F¤ � ¦ µ-¤@��¦:�ʬ ¡�­ �

�f�:�?�8ôY�"� �/���D¤[¤@� ¢ ¥f� � ¤   §�µ ¨ © � ¤Aõ�±~��� � ¤m¤H�Q¦ ÜE¤ � ¤8���  Q©�× ¤ ¡ �:£ ¡8¢ � © ¤ � ¤ ¡8 8¨ �D¦~£�¤^�f©Q£�¦:� ¨ ¤^�"��¤8���Q¤@���ª´�   ���D¤p£p¤m£ ¡8  ��� ¢ ¦:�D¦%� ¨ �Q¦ ÜE¤ � ¤8�����©B¥ © ¤ � £   §E¦:���Q¦:��¦:�"© ¢)� ��ª��   ���D¤p£�¤m£��"ö ��  ¥ � ¤�§��B�  (� ¦ ¨ ���0���D¤ Q©�× ¤ ¡ �:£ ¢"� ¤ � ¤ ¡m 8¨ �D¦~£�¤@�E©Q£p¦:� ¨ «æ� ¨�  ��ª´�   ���D¤p£p¤p£�¯ ¢ £�¦:� ¨)� ¤(��ª´�   ���D¤p£p¦^£�¯ ¢ ���,��� � ¤m¤ ¡m  ¥ © ¦:�D¤@���ª´�   ���D¤p£p¤m£��

Page 10: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

image

model

a 2

aa a

b

b1b

bb

2a 1

A1 A

AAA

2

3

5

B B

B

1B B

34

5

45

34

2

5

34

�f�:�?� ÷�� � ¨�  §p¤ ¢ ��© � ¤ ¨C��  ©¤�Y£E¦:�F�Q¤^�/���D¤�£ ¢ ¥�¤�¥   �Q¤ �4¢ ���f§  "� ¥ ¦:¥ ¢�¨ ¤Z�   ¥   �Q¤ �4¡8 "�^� ¤#£��   �B§�Q¤8� ¡ ¤#£ � Þ � ¢ ��� � Þkø � � ¤J��¤p£��0§  "��¡8  ¥�� ¢ ��¦ © ¦ � ¦:��ª © ¤8� ¨ ¤m¤8�R���D¤ ¨"��  ©��Y£ �þ¢ ��� �T© ª¡ �D¤ ¡@ê ¦:� ¨ §  "��¡m  �o£p¦~£���¤8� ¡ ª   § ¢)� ¨ ¤ ©8��¢ ¦ ¡ ¦%��� ¢"� ¦ ¢ �F��£ ¨ ¦:���6���D¤�¥   �Q¤ �4¨"��  ©��Y£ ��¢ ��� ø �fù�¤p§� ¢ ¦ � £ ¢"� ¤�¦%�,���D¤(��¤@�C���

Ñ�2Y×:;�ÞY58@YÔp9)ßDÛY589�;8Û�ÕoÕo9F;8A8;�3ÕB9�ÖY9�5p3Q7Ê;8A85p3QAm9�Õoá%Ó�@o5�Am9�;8Am×GÖ�Õ�A82Y9Ôp@BÚ�Þ43QAm×GØ�×G7:×:A|á�@QÓÈ3Þ436×G5�@6Ó�×:ÚÏ3QÕB9�2DáDÞ4@BA82Y9F;89�;ßD9�5m×:Ýo9Wß�Ó�58@oÚ 3Q7:Õo9�Ø�5�3Q×�Ô0Ó�9W3QAmÛY589F;�C�×:Am2Y×:Ö+3�;8×:ÖYÕB7:9�Ú�@YßD9�7|=Ñ�2Y9�Ú�9�A82Y@YßK5m9�7:×G9F;/;m×GÚ�Þ�7Gá�@oÖKA82Y9�9pâ4Ô82?3QÖYÕB9Ï@QÓ�Ó�9W36A8ÛY5m9�;�Ó�58@BÚ @oÖ�9�Ó�9W36A8ÛY5m9�Õo5m@oÛYÞA8@�Am2Y9�@oAm2Y9�5WïY36Ö4ß�A82Y9FÖÿÔ#@oÚ�Þ43658×:;8@BÖÏ@QÓ-A82Y9�ÖY9FC�7GáÏÔ#@oÚ�ÞYÛYAm9Wß�×:Ö�Ýo3658×�3QÖDAm;�C�×:A82!A82Y@B;89Ó�@B5A82Y9�;p3QÚ�9ÏÔp@BÖ�<4ÕBÛY5�36A8×:@oÖK@oÖ�Am2Y9�Ú�@YßD9�7|=�ù|ÖKÞY5�3BÔpA8×�Ôp9�A82Y9%Ó�9W3QAmÛY589F;ÖY9�9Wß ÖY@oA�Ø493Q7:ÕB9�ØY5�36×�Ô�Ø�ÛYA�ÚÏ3)á�×:Ö4Ôp7:Û4ßD93QÖDá�@6Ó�A82�9/ßD×�� 9F589�ÖDA8×�367[;8Am58Û4Ô#A8ÛY5m9�;�×GÖ ö��DïB���Fø8=

�ã»%$ .¸o�Í�Í?Æ�*ú�/-�Ã�¿�ÉÑ254-ÄQÂ?ÉO½�DÚ�@D@oAm2åÞ�7�36ÖY9�ÔpÛY58ÝB9�;�3Q589�589)Ôp@oÕBÖY×:;89Wß ÛY;8×:ÖYÕ 3!Ô�3QÖ�@oÖY×�Ô�367[Ó�5�3QÚ�9�Ôp@BÖY;8Am58Û4ÔpAm×:@oÖ�A82?3QA589F7G×:9�;�@oÖ�Am2Y9 Ú�9W36;8ÛY5m9�Ú�9�ÖDAÏ@6ÓÌ;�ì:ë@�QîOó6èFî4ê�D 3QÖ4ß ê��)çpë�ë´�6îDó6èFî4ê�D Þ?@o×:ÖDA8;�7ÊÓ�@oÛY5�;8Û4Ôm2Þ?@o×:ÖDA8;E36589�Ú�9)3Q;8Û�589W߯Ó�@o5�9)3oÔm2ÏÔ�3QÖ�@oÖY×�Ô�367YÓ�5p3QÚ�9ö����Fø8=QÑ�2�9�ØY×:A�36ÖYÕo9FÖ4Ôpá�Þ4@B×GÖDAm;�Ø4@BÛYÖ4ß;89FÕoÚ�9�ÖDA8;�@QÓEÔpÛY5mÝo9�úMn Ô#ÛY58ÝB9�;�û�A82?3QA3Q5m9589WÔ#@oÕoÖ�×G;m9WßKÛY;m×GÖ�ÕÏA82�9×:Ö�Ýo3658×�3QÖDA�×:Ö4ßD9#âO×:ÖYÕÞ4365�3oßO×GÕBÚ ú|3�Ú�@B589åÔp@BÚ�ÞY7:9�A89KßD9�;�Ô#58×:ÞYA8×:@BÖæ@6Ó/A82Y9�ÞY58@YÔp9�;m; ×:;ÏÕB×GÝB9�Ö ×:Öåö����Fø�û�=(Ñ�CE@9pâ43QÚ�Þ�7G9F;�@QÓ\n ÔpÛY5mÝo9�;�3Q5m9Õo×:Ýo9FÖÏ×:ÖJ<4ÕoÛY5m9r�QØ[=

Ñ�2Y9ÿÓ�@oÛY5�Ú�9W3Q;mÛY589)ß Þ4@B×GÖDAm;�Ó�@B5Ï9W3BÔ82²n ÔpÛY5mÝo9�3Q5m9 ÞY589F;89�5mÝo9Wß Ø�á ÞY5m@WÙp9WÔ#A8×:@oÖú¬ßO×G;mA8×:ÖYÕBÛY×:;82Y9Wß�û�ï-3QÖ4ß�×:A�×:;�A82�58@oÛ�Õo2�A82�9�;89�Am243QAC�9�;89�9�2Y@QCTAm@+9#âOAm9�Ö4ß 2�áDÞ?@oAm2Y9�;89F;Ó�@B5hn ÔpÛY5mÝo9�;)=4Ñ�2�9ý36ÞYÞY5m@�3oÔm2!ØYÛY×:7�ßD;�ßD×:589WÔ#A87:á!@oÖÏAm243QA�Ó�@o5�3Q7:Õo9�Ø�5�3Q×�Ô�Ó�9W36A8ÛY5m9�; ?OÓ�@o5�3��\Gh � PF\G`Qq|��ðYZo��\:`oaq|lBn�kpP)Zo`Qq�\G`Ba/r { aWZBR�np`Qq�P��\û�ü^ý[}-n�k�r�`�R�n�r��|Z { n���P)Z { \:`o_on � np`o_Bn�`Qq�\G`6c�Wr { \�r�`Qq|�pxD��P�}-np�)n { NQq|lBn��|n�R�ZB�|q-��n(��Zo`Bk�q�\:PW`Drp]~]Gs_Bn � np`B_onp`Qq�P)`q|lon(��PWZ { \:`Q�Wr { \�rF`Qq|��ZB�|np_��P { \G`B_onph)\G`BaoNYr�`B_��|P�`BPWq|l6\G`oa�k#rF`���n�aQr#\G`onp_�\G`�Zo��\:`oa�q|lonp�|n���P { nphQq|np`o��\:PW`�x�z��Er { np�|Z6]GqpNq|lon�P)`Q]Gs�k�P)`o�|q { r#\G`Qq�Zo�|nm��ZQ]?��P { n�hQq|np`B��\GP)`\:��q|P � PF]GP)aWs)x

Page 11: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

Þ436×:5�@6ÓE2DáDÞ4@BA82Y9�;m9�;�ú�áD×:9�7�ßD×:ÖYÕÏ9�×:ÕB2�AßD×:;mA8×:ÖYÕoÛ�×G;m2Y9WßKÞ?@o×:ÖDA8;pû�ï�@BÖY9¯Ô#@oÛY7�ß�A�3QÒB9�;89�Am;@QÓ<4ÝB9Þ?@o×:ÖDA8;�Ø?9�A|C�9�9�ÖKA82Y9�2DáDÞ4@BA82Y9�;m9�;/36Ö4ß Ôp@BÚ�Þ43Q5m9×:Ö�Ýo3658×�3QÖDAm;�Ôp@oÚ�ÞYÛ�A89Wß�Ó�@o5�Am2Y9�;m9Þ?@o×:ÖDA8;�C�×:A82 Am2Y@o;m9!@oÖ A82Y9!2DáDÞ4@BA82Y9F;8×:;89Wß Ú�@OßO9�7|=[Ñ�2Y9 3BÔpA8Û4367�Þ4@B×:Ö�Am;�ÛY;89)ß Am@åAm9�;8AÔp@BÖY;8×:;mA89�Ö4Ô#áÿ36589�;82�@QC�Ö+×:ÖJ<4ÕBÛY589r�Y=���9�ÛY;m9�A82Y9�;m9/Þ?@o×:ÖDA8;�Ø?9WÔ�36ÛY;89�?÷o=h��@o5�9 � Ôp×:9�Ö4Ô#áþ5m9W3Q;m@oÖY;�×:A�×:;�ÛYÖ4ßD9�;m×:5�3QØ�7G9!Am@ Ôp@oÚ�ÞYÛ�A89 3Q7:7�@QÓ�Am2Y9!×:Ö4ßD9�Þ?9�Ö4ßD9FÖ�A×:ÖDÝo3Q5m×�36ÖDA8;�Ó�@o5�A82Y9KßD×:;8A8×:ÖYÕBÛY×:;82Y9)ß�Þ?@o×:ÖDA8;W=f��9!ÖY9F9Wß�Ôp@BÚ�ÞYÛYA89!9�Ö�@oÛYÕB2þ@BÖY7:á�A8@ÞY5m@QÝD×�ßO9�3Ôp@oÖ~< ßD9�ÖDA�9�;8Am×GÚÏ36A89�@QÓ[Ôp@oÚ�Þ436A8×:ØY×:7:×:A|á�=FÑ�2Y9�589#Ó�@o5m9oïD@oÖY7:á�A|CE@�Ôp@oÖ�<?ÕoÛY5p3)àAm×G@BÖY;�@QÓ0<4ÝB9�Þ?@o×:ÖDA8;�3Q5m9�ÛY;m9Wß�C�2Y×�Ôm2ÏáD×:9�7�ß�3Am@oA�3674@6Ó[Ó�@BÛY5�ÞY5m@WÙp9WÔ#A8×:Ýo9�×:ÖDÝo3Q58×�36Ö�Am;W=

�Y=���9�C�×:;82 Am@ÿÔ#@oÚ�ÞYÛYAm9/Ú�9)3Q;8Û�589�;Am243QA36589�;8áDÚ�Ú�9�A85m×�ÔC�×:A82�589�;mÞ49WÔ#A/Am@ÏA82�9ÏßD×:;|àAm×GÖ�ÕoÛY×:;82�9Wß Þ?@o×:ÖDA8;)ï[3QÖ?ß ;m@ÿ3�<YÓ�A82�Þ?@o×:ÖDA�Ó�@B5�9)3oÔm2 Ôp@oÖ?Ô�3)ÝD×GA|á�×G;Ôp@BÚ�ÞYÛYAm9Wß�3QÖ4ßÛY;m9Wß 36;�;82Y@QC�Ö!×:Ö,<4ÕBÛY589E�Y=

b

fifth point

pointsdistinguished

a

�f�:�?�8þY� ö  "�¢ � ¢ ¦ �  §�¦%����¤ � ¤p£�� ¡ © � �F¤p£5���D¤ � ¤ ¢"� ¤EÿR�Q¦^£���¦:� ¨ ©o¦~£M�D¤@�Ú�   ¦:���:£ ¨ �D¦ ¡ � ¡m  © � � © ¤©6£�¤@�E�   §  "� ¥ v��!i��åi�� i �Q¦ Ü�¤ � ¤8����µf��¤��   ¦%���-¦:��� ¢"� ¦ ¢ ���:£���� ¢ ���D¤ � ��� ¢ � ¡8  ¥���©���¦:� ¨ £  ¥ ¢ �Fª�± ¨ �D¦ ¡ ��¦^£�¦:�D¤� ¡ ¦:¤8���:± ¨ ¤ ¡8  ¥f��©���¤�¦:��� ¢"� ¦ ¢ ���:£ © ¤8� ¨ ¤8¤��r���D¤B§   © � �Q¦^£���¦:� ¨ ©o¦~£ �B¤@�¶�   ¦:���:£  §�¤ ¢Q¡ � ¡8  � ¡8¢ �F¦%�°ª8± ¢ ���·���D¤ ¡ ¤8��� ��¢)� �   ¦:�F�   §/���D¤   ���D¤ � �����D¦^£(ª)¦:¤ � �)£H§   © � ¦:��� ¢"� ¦ ¢ ���:£^± ¢ ����   ¤#£�£   ©6£�¦:� ¨�¢ £�ª)¥�¥�¤8� � ¦ ¡�¡8  �B£�� � © ¡ ��¦   ���H���D¤p£p¤�¦%��� ¢"� ¦ ¢ �F��£ ¢"� ¤�£�©� ¡ ¦:¤8�����   ��ª��   ���D¤p£�¦~£p¤¡m  ¥f� ¢ ��¦ © ¦ � ¦:��ª8�

Ñ�2Y9/Ô#@o585m9WÔpAmÖY9�;8;�@QÓ�A82Y99#âOAm9�Ö4ßD9)ßK2�áDÞ?@oAm2Y9�;8×:;�×G;�A89�;mA89Wß�ØDá Ôp@oÚ�Þ43658×:ÖYÕ�Am2Y9Ó�@oÛY5Ú�9W36;8ÛY5m9Wß�×:ÚÏ36Õo9�×GÖDÝo3658×�3QÖDA8;-C�×:A82�Am2Y9�ÚÏ36A�Ôm2Y×:ÖYÕ�@oÖ�9�;E@BÖ�A82Y9�Ú�@YßD9�7|=QÑ�2Y9�Ôp@o;mA-Ó�ÛYÖ4Ô�àAm×G@BÖÏÛY;m9Wß�A8@�Am9�;8A�Ôp@oÖY;m×:;8A89FÖ4Ôpá!9pâYÞY7:@o×:A8;�@6Ó�Am2Y9�Ó¬3oÔpA�Am243QA�A82�99pâYÞ49)ÔpA89Wß�9�5m58@o5m;�×:ÖÏAm2Y9Ú�9W36;8ÛY5m9Wß�×:Ö�Ýo3658×�3QÖDAm;036589�58@BÛYÕo2Y7:á�ÞY58@BÞ4@B58A8×:@BÖ43Q7?A8@�Am2Y9�×:5�Ýo3Q7:ÛY9�;�ö�Dï���òø´?

� � ¥�¾� =

������¾����,¾�¾

���� Ä

Page 12: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

3QÖ?ßAm2Y9E9#âOAm9�Ö4ßD9)ß�2DáDÞ4@BA82Y9�;m×:;�×:;�3oÔFÔp9�ÞYAm9Wß�×~Ó � 7:×:9�;[Ø?9�7:@QCþ3�Am2Y589�;m2Y@o7�ß�=��[×:ÕBÛY589�;\��3QÖ4ß÷ l�;m2Y@QC 9pâ43QÚ�Þ�7G9F;�@QÓ�2Dá�Þ?@oAm2Y9�;m×G;�9pâYA89�Ö�;8×:@oÖ�Ó�@o5hn ÔpÛY5mÝo9�;)=0º�@oAm9×:ÖJ<4ÕoÛY5m9·�oßÿ2Y@QCA82�9/Ø?9�ÖY9�<?A�@6ÓEÔp@oÚ�ØY×:ÖY×:ÖYÕ�2DáDÞ4@BA82Y9�;m9�;�5�36A82Y9�5�Am243QÖ Û�;8×:ÖYÕ�×:Ö4ßD×:ÝD×�ßDÛ43Q7�2DáDÞ?@oA82�9�;89�;�×:;589)3Q7:×:;89Wß 36;�Ô�3QÖ!Ø?9�@oØY;m9�58ÝB9Wß!ØDáÏAm2Y9�Ø49�AmA89�5�Ú�@YßD9�7�5m9�Õo×:;mA85�36A8×:@oÖ!×:ÖR�oÔQ=

� �

� è�f�:�?����� ¬ ¢�­ £ �  "¨ £ ¢ �»©��  �¡8¡p� ©��Q¤@�,��¦:¤ ¨   § ¢ £�� ¢ ���D¤ � �/���D¤!¦%���Q¤@�6¦%� ¨ £ ¡ �D¤F¥�¤ ¡m "�@� ¤ ¡ � � ª�^ �¡m¢ ��¤p£5���D¤5³ ¡ © � �F¤p£�¦:�»¬ ©�­ �(���D¤p£�¤ ¢"� ¤E©Q£p¤@�J�   §  "� ¥ ¢ � ¤@�"��¤��F�Q¤^�5��ª´�   ���D¤#£�¦~£H§  "� ���D¤¥   �Q¤ �¸¨ �D¦ ¡ �%¦^£(�F¤ � ¦ µ-¤@�r©6£�¦:� ¨�©8¢Q¡@ê � �� �× ¤ ¡ ��¦   �¦:�6¬ ¡�­�¢ ���h� ��  ��¦:�Q¤p£k��¤ � ª ¨Q �  � � ¤ ¨ ¦~£�� ��¢ ��¦   �  §f���D¤  Q©�× ¤ ¡ �°� � §^± ¢ £-¦%�/¬�� ­ ±   � � ªf���D¤ �^ "¨ ¤ � ³ ¡ © � �F¤�¦~£f©Q£�¤^��§  "�Ø� ¤ ¡8 8¨ �D¦:��¦   �����D¤ � ¤ ¨ ¦~£�� ��¢ ��¦   �¦~£ ¨Q �  ��¦:�6���D¤ � ¤ ¨ ¦   �   §r���D¤ ¡ © � ��¤�± © ©��(¤@�"� ��¢ �  )�^¢ ��¤p£Ø�  � "� � ª   �F¤ � ���D¤ � ¤p£��   §/���D¤  Q©�× ¤ ¡ ���� © © £p¤�8©B¤8��� � ª ¨ ¤Z� ¢ ��¤ ¨Q¢ ¦:��¤^� ¢¨ ¤   ¥�¤�� � ¦ ¡8¢)�:� ª ¨� "� £�¤�©����Q¤ � £�� ¢ ���Q¦:� ¨  §Z���D¤�£ ¡ ¤8�D¤�¦:�̬�� ­¡8  ¥�� ¢"� ¤@�r�   ¬ ¡�­ �

� ��¹@|D¸�·(|�|D¹8µ(²Ñ�2Y9Ï36Ø4@QÝB9¯36ÞYÞY58@D3oÔm2Y9�;�CE@B58ÒKCE9�7:7ÊÓ�@B5�Am2Y9�589)Ôp@oÕBÖY×:A8×:@oÖK@QÓ�ÞY7�3QÖY9�3Q7:ÕB9�ØY5�36×�Ô@BØoÙp9WÔpAm;3QÖ?ß A82Y@B;89�Ôp@oÖDAp3Q×:ÖY×:ÖYÕ�;8Ú�@D@BA82�ÞY7�36ÖY9åÔpÛY5mÝo9�;)=�ù|Ö Ó¬3BÔpAWï�Am2Y9å2DáDÞ?@oA82�9�;8×:;!9pâYA89�Ö�;8×:@oÖ

Page 13: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

� �

��f�:�?������� � ¨�  ³ ¡ © � ��¤p£ ¢"� ¤f§   ©����   �Ê���D¤�£�� ¢ ���D¤ � ¬ ©�­¢ ��� ¡8  ¥ © ¦:��¤^� © ¤�§  "� ¤k��ª´�   ���D¤p£p¦^£��¤ � ¦ µ ¡8¢ ��¦   �r¬ ¡�­ �

ÞY5m@YÔp9�;8;�×:;�3�Ôp58Û?Ôp×�3Q7-;8Am9�Þå×:Ö!×:Ú�ÞY58@QÝD×:ÖYÕ�A82Y9�9 � Ôp×:9�Ö?Ôpá 3QÖ4ß!5m9�7:×�3QØY×:7:×:A|á�@QÓ�A82Y9�C�2Y@B7G9@6Ó�A82�9�×:Ö4ßO9pâY×GÖ�Õ�Þ43Q5p3oßD×:ÕoÚ ÛY;m9Wß!×:ÖÌdÊäf��ù@��=�Ñ�2Y×:;E×:;�36ÞYÞ43Q5m9�ÖDA�Ó�@o5�A|C�@�589W36;8@oÖ�; ?  ��9�Ô�36Ö/3Q;m;8ÛYÚ�9E3�Ú�Û4Ôm22Y×:ÕB2Y9�5[Ôp@BÖ�< ßD9�Ö?Ôp9�×:Öý3�ÝB9�58×�< ÔF3QA8×:@BÖ�;pÔp@o5m9EC�2�9�ÖÚ�ÛY7:A8×:ÞY7:9Ó�9)3QA8Û�589ÕB58@oÛ�ÞY;�243)Ýo9�2DáDÞ4@BA82Y9F;8×:;89WßÿA82Y9�ÞY5m9�;89�Ö?Ôp9�@QÓ�3QÖ!@oØoÙp9)ÔpA�×:Öÿ3�;�Ô#9�ÖY9o=

  Ñ�2Y9�×:Ö4Ôp5m9W3Q;m9Wß�ÖDÛYÚ/Ø?9�5�@QÓ-Ú�@OßO9�74Am@/×:ÚÏ36Õo9�Ôp@B58589F;8Þ?@oÖ4ßD9FÖ4Ôp9�;Þ�58@QÝD×�ßD9Wß�A82�58@oÛ�Õo29pâYAm9�ÖY;8×:@BÖ�×GÚ�Ú�9)ßD×�3QA89F7Gá!7:9W3BßD;�A8@!Ø49FA8A89F5Ú�@YßD9�7�5m9�Õo×:;8Am5�36A8×:@oÖ�3QÖ4ß�;�Ô#9�ÖY9ÏÛ�Ö4ßD9�5 à;mA�3QÖ?ßD×:ÖYÕ4=

Ñ�2Y9ýÓ�@o7:7:@QC�×:ÖYÕ;89)ÔpA8×:@oÖ�;�2Y×:Õo2�7G×:ÕB2�A�2Y@QC 589�;mÛY7:A8;3QØ?@oÛ�A�2DáDÞ4@BA82Y9�;m×:;�9pâYA89FÖY;8×:@oÖKÔ�3QÖ Ø?936ÞYÞY7:×:9WßKA8@å3ÿÝo3Q58×:9�A|áK@QÓ�@BA82Y9F5/@BØoÙp9WÔpAÏÔp7�36;8;89F;Ï3QÖ4ßK;m@å×:Ú�ÞY5m@QÝo9�A82Y9!Ô�3QÞ436ØY×:7:×GAm×:9�;@QÓÔpÛ�58589FÖ�A�×:Ö�Ýo3658×�3QÖDA�×:Ö4ßO9pâY×GÖ�Õ/Ø436;89Wßÿ589WÔp@BÕoÖY×:Am×G@BÖ!;8áD;8Am9�Ú�;W=

�Ê»�º g Ë�ÆWÉD¿�½F¾�Í4¿�½�ÆWÍKÍ?Æ *-ÉDÄ625-ÅÃ4½W½FÉY½�ÍYÌ �E�"!)ÉYÐQÆQ½ù|ÖDÝo3Q5m×�3QÖDA8;(Ó�@o5�Am2Y589F9¯ßD×:Ú�9�Ö�;8×:@oÖ43674@BØoÙp9WÔpAm;3Q589�ÖY@QC�Ø?9WÔp@oÚ�×:ÖYÕ�Ó|3QÚ�×:7:×�365�×:Ö!A82Y97:×:A89F5|à36A8ÛY5m9o=YÑ�C�@/9#â�36Ú�ÞY7:9Ôp7�3Q;8;m9�;�@6Ó�@oØoÙp9WÔ#A8;�36589Ôp@BÖY;8×�ßD9�5m9Wß�Ø49�7:@QC Ó�@o5�C�2Y×�Ôm2!9pâYA89�ÖY;m×:@oÖ

Page 14: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

Ô�36Ö+Ø?9/36ÞYÞY7:×:9Wß�=�·�"!)ÉYÐ6Æò½/1(Í ½)½�ÉY½)½�¾Å¿�À�Î�Í?Æ)ÃYÆW¾ÅÍ4¿-Ã-h.0'0o»o�ÉDÆ)Ä"'

ù|ÖDÝo3Q5m×�3QÖDA4×:Ö4ßO9pâY×GÖ�Õ�Ó�ÛYÖ?ÔpA8×:@oÖ�;�Ô�36ÖØ49(Ú�9W3Q;mÛY589WßýÓ�@B5[@oØoÙ#9WÔpA8;-Am243QA-3Q589(ÞY58@WÙ#9WÔpA8×:ÝB9�7:á9 �BÛY×:Ýo3Q7:9�ÖDA�Am@�;8@o7:×�ßD;�@6ÓÈ5m9�Ýo@B7:ÛYA8×:@oÖ!ö:÷ Fø8=YÑ�2�9ýÔ#@oÚ�ÞYÛYAp3QAm×G@BÖ!@QÓ�A82Y9�×GÖ?ßD9pâY9�;�5m9�7:×:9�;�@BÖA82�9/ßD9�Am9WÔpA8×:@BÖ+@6Ó�7G×:ÖY9F;E@6Ó�ØY×:A�36ÖYÕo9FÖ4Ôpá+36Ö4ß�×:Ö�Q49WÔpAm×:@oÖ!×:ÖÏA82�9�×:ÚÏ36Õo9�@6Ó�Am2Y9@YÔ�Ôp7:Û4ßD×:ÖYÕØ?@oÛYÖ4ß�3Q58á�@QÓ-A82Y9�@oØoÙp9WÔ#AW=���@QCE9FÝo9�5)ïDÞY58@YßDÛ4Ô#×GÖ�Õ�A82Y9Ôp@B58589F;8Þ?@oÖ4ßD9FÖ4Ôp9�Ø49�A|C�9�9�ÖKßD×�� 9�5 à9�ÖDA�;m×�ßD9�;�@6Ó�Am2Y9@oØoÙ#9WÔpA�36ÞYÞ?9W3Q5m;�3QA�<45m;8A�Am@�Ø49�324365�ß�A�36;8Ò�=YÑ�2�×G;�ÔF3QÖ!Ø49�@QÝo9�5pÔp@oÚ�9ÛY;m×GÖ�ÕÏA82�9Ó�@B7:7G@QC�×:ÖYÕ�;8Am5�36A89�ÕBáå3QÖ4ßÿ9pâYÞY7:@o×:A8×:ÖYÕ�Am2Y9�Ó¬3BÔpA�A82436A�A82�9/×:ÚÏ3QÕB9�;�@QÓ�A82Y9�A|CE@;8×�ßD9F;�@QÓ-A82Y9�@BÛYA87:×:ÖY9�36589�ÞY5m@WÙp9WÔpAm×:Ýo9�7:áÏ9��oÛ�×GÝo367:9�ÖDA�A82Y5m@oÛYÕB2 3243658Ú�@BÖY×�Ô�2Y@BÚ�@o7:@oÕBá/@6ÓA82�9ÞY7�3QÖY9�ú�;89�9/<?ÕoÛY5m9¯÷B÷Wû�?

÷B=O�O9W3Q5pÔ82!Am2Y9�×GÚÏ36Õo9�Ó�@B5kn ÔpÛY58ÝB9�;W=B�Y@B5�9W3BÔ82 ÔpÛ�58Ýo9�Ó�@BÛYÖ4ß�ïB2DáDÞ4@BA82Y9�;m×:;89Am2Y9�ÞY5m9�;|à9FÖ4Ôp9@6ÓÈ3QÖ!@BØoÙp9WÔpA�@QÓ�5m9�Ýo@B7:ÛYA8×:@oÖÊ=

��=O#�9�Am9�58Ú�×:ÖY9�C�2Y9�Am2Y9�5�3QÖDá!Þ43Q×:5�@QÓkn ÔpÛY58ÝB9�;/36589�ÞY58@WÙ#9WÔpA8×:ÝB9�7:á 9 �BÛY×:Ýo3Q7:9�ÖDA�ÛY;8×:ÖYÕAm2Y9�Ô�36ÖY@oÖY×�Ô�367DÓ�5p3QÚ�9�Ôp@oÖY;mA85mÛ4ÔpA8×:@BÖH7QA82�×G;�Ô�3QÖ�Ø49�3BÔm2Y×:9�Ýo9Wß�Û�;8×:ÖYÕ�A82Y9�Ú�9FA82Y@Yß�9�Ú�àÞ�7G@QáB9Wß�Am@/;m@o7:Ýo9-Ùp×:Õo;p3)CþÞ�Û$#%#�7:9�;�ÕB×GÝB9�ÖÏ×:Ö ö����Fø8=BÑ�2Y×:;E×:;�A82Y9�2DáDÞ4@BA82Y9F;8×:;�9pâYA89�Ö�;8×:@oÖ;mA�36Õo9o=

��='&�3QA�Ôm2�Ap3QÖYÕB9�ÖDA8;!3QÖ4ß�@oAm2Y9�5%Ó�9W3QAmÛY589F;+Am243QA!3Q7:7:@QC A82�9 ×:Ö�Ýo3658×�3QÖDAm;/5m9 �BÛY×:589Wß Ó�@o55m9WÔp@BÕoÖY×:A8×:@BÖ+Am@/Ø?9Ú�9W36;8ÛY5m9Wß�=

axis of symmetry

C

B

A

�f�:�?�"������� �,���D¤�¦:¥ ¢�¨ ¤   § ¢ £  )� ¦:�   § � ¤8�  )� ©��Ŧ   ��±����D¤h� ¨�  £p¦:�Q¤p£O¬ ¡ © � �F¤p£ � ø ¢ ��� ø ( ­¢"� ¤� �� �× ¤ ¡ ��¦:��¤ � ª�¤)�8©o¦:� ¢)� ¤��F�+*-,+.-/��

Page 15: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

��ÍB-�'0*-ÉOÇÊÄQÃ-0�E�"!)ÉOÐ6Æò½ù|ÖDÝo3Q5m×�36ÖDA8;�Ô�36ÖåØ?9¯Ô#@oÚ�ÞYÛYAm9WßÿÓ�@o5�@BØoÙp9WÔpAm;A82436A�36589�Ø43Q;m9Wß @BÖ Þ?@o7:áD2Y9WßD5p3Yï?@o5�Ó�@o5

@BØoÙp9WÔpAm;�C�×:A82!3�ÞY7�3QÖY9�@QÓ�ØY×:7�3QA89F5�3Q7�;máDÚ�Ú�9�A85má+ö��"�)ø8=��@QCE9�ÝB9�5Wï�Õo5m@oÛYÞY×:ÖYÕ�A82�9�Ó�9W3QAmÛY589�;5m9 �BÛY×:589Wß Am@�Ó�@B58Ú A82Y9�×GÖDÝo3658×�3QÖDA8;�×:;+3K24365�ß Ap3Q;mÒ =���ÖY9åC�3)á Am@�@QÝo9�5pÔp@oÚ�9�A82Y×:;Ï×:;Am@ÏÛY;m9�A82Y9R�21 î4è%ì�î�"�Qô�ìM�6îDëEÔp@BÖY;8Am58Û4ÔpAm×:@oÖ�@QÓ�� 3)á�Ö�9�5�ö���lFø�A8@!2Y×:ÕB2Y7:×GÕB2DA�;8ÚÏ3Q7:7Ê7G@YÔ�367Ó�9)3QA8Û�589�;�Am243QA�Ú�×:Õo2DA/Ô#@oÚ�9�Ó�58@oÚ 3 Þ?@o7:áD2Y9WßD5p3Q7�;mA858Û?ÔpA8ÛY5m9å3QÖ?ß Am2Y9�Ö A82�9�;89 Ô�36ÖþØ?9ÕB58@oÛ�Þ49Wß�Am@oÕo9FA82Y9�5!×:ÖDA8@�3oÔpAmÛ43Q7�Þ4@B7:á�2�9WßD5�3�=�Ñ�2Y9�×GÖDÝo3658×�3QÖDA8;�×:Ö ö���lFøýÔF3QÖ�Ø?9 ÛY;m9 A8@ßD9FA89WÔpA�A85m×:2Y9WßD5p3Q7�Ýo9�5mA8×�Ôp9�;�@QÓ�Ýo3Q5m×G@BÛY;A|áDÞ?9�;W=f�Ê×GÕBÛY589 ÷���;82Y@QC�;2�@QCTÓ�9W3QAmÛY589�ÕB58@oÛ�ÞY;Ô�36Ö!Ø49�9pâYA85p3oÔpAm9WßÿÓ�58@BÚ A82Y9F;89;m×GÚ�Þ�7G9�ÝB9�58Am×�Ô#9�;�Am2Y58@BÛYÕo2!9pâYA89FÖY;8×:@oÖÊ=

b.

a.

�f�:�?���C¦�� � � ¦��D¤^� ��¢)� ��¤ � �Ŧ ¡ ¤p£   § ¢ £���¤ ¡ ¦ µ ¡ £�� ¢ ��¤ ¡8¢ � © ¤k�Q¤8�Ť ¡ ��¤^�k©6£�¦:� ¨ ���D¤ ¢ �3�D¤E¦:��� ¢"� ¦ ¢ ���:£¦:� *4365-/��0���D¤p£p¤ ¡8¢ � © ¤f©Q£p¤@���   ��ª��   ���D¤p£�¦~£p¤����D¤(¦%�D¦:��¦ ¢)� � � ¤p£�¤�� ¡ ¤   § ¢ �  )� ª��D¤@� ��¢)�� Q©�× ¤ ¡ �:±  "�Ê¢ � Q©�× ¤ ¡ � ¨ ¦:��� ¢ � �^¢ �D¤   § © ¦ �^¢ ��¤ ��¢)� £�ªW¥�¥�¤8� � ª�� �Y �¡8¢)� ��ª´�   ���D¤p£p¤p£ ¡8¢ � © ¤�¤^�"��¤8���Q¤@� © ª ¡8  ¥ © ¦:�D¦%� ¨� ¢ ¦ � £   §���¤ � �Ŧ ¡ ¤p£æ��� ¢ ��� ¢ ��¤ ¡8 )�:� ¦:��¤ ¢"�?� ¦:��¤(£�¤ ¨ ¥�¤��F��£�� � �D¤8� ¢ £�©)� ¡ ¦:¤8������©o¥ © ¤ �-  §���¤ � �Ŧ ¡ ¤p£� ¢ ��¤ © ¤8¤8� ¨"��  ©���¤^�/���D¤H§�© �:� � �� �× ¤ ¡ ��¦:��¤�¦:�F� ¢"� ¦ ¢ ���:£   §7*488õ9/ ¡8¢ � © ¤�¥�¤ ¢ £�© � ¤@�"�

äÊâYA89FÖY;8×:@oÖKÚÏ3)áå367G;m@,<4Ö?ßå3�5Ã}@B7:9/×:ÖåÔp@BÚ/Ø�×GÖ�×GÖ�ÕÏA82�9�;8×:Ú�ÞY7:9Þ?@o7:áD2Y9WßD5p3ÏAm243QA365895m9WÔp@oÕBÖY×:;89Wß�×:Ö ö��"�)ø8ï)9W3BÔ82�@6Ó C�2�×�Ôm2�243Q;(;8×~â/;8×�ßD9F;WïQ×:ÖDA8@�7�3Q5mÕo9�5-Þ?@o7:áD2Y9WßD5p3Q7Y@BØoÙp9WÔpAm;�A82436A36589�Ú�@o5m9�Ó|3QÚ�×:7:×�365-×GÖ!Am2Y9�CE@B587�ß�=

�Ê»%$ :E4-Ã4½�¾4;8Á�¿ÊÂ�Ã�ÄQ¾�ÃY¿[ÆQ½>-5m@WÙp9WÔ#A8×:Ýo9 ×:ÖDÝo3Q5m×�3QÖDA8;�Ó�5m9 �BÛY9�ÖDA87:á 589��oÛ�×G5m9å3�7�3658Õo9!ÖDÛYÚ�Ø49F5Ï@QÓ�Ó�9W3QAmÛY589F;ÏA8@�Ø49�9pâDàAm5�3oÔ#A89WßK9 � Ô#×G9FÖ�Am7:á!Ó�58@BÚ�3�;�Ô#9�ÖY9o=ÊÑ�2Y9�Õo5m@oÛYÞ�×GÖ�ÕÏÞY5m@oØY7:9�Ú A82436A�5m9�;8Û�7GAm;Ó�58@oÚ�Am2Y9�;m95m9�7�3QA8×:ÝB9�7:áÏ7�3Q5mÕo9�Ó�9)3QA8Û�589�Õo58@BÛYÞY;�Ô�3QÖKØ49�9W3Q;m9Wß ×~Ó03%ÖDÛYÚ/Ø?9�5�@QÓE×:ÖDÝo3Q5m×�36ÖDA8;�A8@+3%;8×:Ú�àÞY7:9�5�×:ÚÏ36Õo×:ÖYÕ/ßD9#Ó�@o5mÚÏ3QA8×:@BÖ+3Q5m9�Ú�9W3Q;mÛY589WßÌ<458;mA�ú¬3 � Ö�9�×:ÖDÝo3Q5m×�3QÖDA8;�Ôp@oÛ�7�ß�Ø?9�ÛY;89Wß+Ó�@o5

Page 16: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

9pâ43QÚ�Þ�7G9)û�ï?@o5�Am2Y58@BÛYÕo2 Am2Y9�ÛY;89@6ÓO�BÛ43Q;m×~à¬×:ÖDÝo3Q5m×�36ÖDAEö��FøEú�×GÖOÓ�@o5mÚÏ3Q7:7:á�ï��BÛ43Q;m×^à|×:ÖDÝo3Q58×�36Ö�Am;3Q5m9�Ú�9W3Q;mÛY589�;�A82436AE5m9�ÚÏ3Q×:Ö!3QÞYÞY5m@)âY×GÚÏ36A89�7:á�×:Ö�Ýo3658×�3QÖDA-@QÝo9F5�3;mÞ49WÔ#×�<�Ô�5p3QÖYÕB9�@QÓ�ÝD×:9�C�àÞ?@o×:ÖDA8;�ûF=�Ñ�2Y9F;89å36589 Ø?9�ÖY9�<�Ôp×�3Q7�36;�A82Y9F×G5%Ó�@o5mÚÏ3QAm×G@BÖ�589 �BÛY×:5m9�;+3K;mÚÏ3Q7:7:9�5�ÖDÛYÚ/Ø?9�5�@6ÓÓ�9W36A8ÛY5m9�;W=

�Ê×:58;mAWïB2�áDÞ?@oAm2Y9�;89F;036589�Ô#589W36A89Wß%A82Y5m@oÛYÕB2�×GÖ?ßD9pâY×:ÖYÕ@oÖ�Am2Y9�C�9W3QÒB9�503 � ÖY9�@o5��oÛ?3Q;8×~à×:ÖDÝo3Q58×�36Ö�Am;�ú�A82�9�×:Ö4ßO9pâY×GÖ�Õ�9F5858@B5EØ?@oÛ�Ö4ßD;�@oÖ�A82�9�;89�×:ÖDÝo3Q58×�36Ö�Am;�3Q589�7�3Q58ÕB9�5E36;EAm2Y9�á�243)Ýo9A8@ 3oÔ�Ô#@oÛYÖDA�Ó�@B5�9�585m@o58;!×:Ö A82Y9�×GÚÏ36Õo×:ÖYÕ Ú�@YßD9F7�ûF=-Ñ�2Y9�Ö[ï�Þ436×:58;�@QÓÞY5m@)âY×GÚÏ367EÕB58@BÛYÞY;Ô�36Ö Ø?9ÏÔp@oÚ�ØY×:ÖY9WßKÛY;m×:ÖYÕ 9pâYA89FÖY;8×:@oÖ�A8@�Ó�@B58Ú 7�3Q58ÕB9�5ÕB58@oÛ�ÞY;A82?3QAÞ?@o;m;89�;�ÞY58@)Ùp9WÔpAm×GÝB9×:ÖDÝo3Q58×�36Ö�Am;W=0�DÛYØ�;89 �BÛY9�ÖDAm7GáDï[36Ö�á�Ö�Û�Ú/Ø?9�5@6Ó0Am2Y9�589WßOÛ4Ôp9Wß Õo58@BÛYÞY;Ô�36Ö�Ø49ÏÔp@BÚ/Ø�×GÖ�9Wß�=Ñ�2Y×:;�×:;�9pâ43oÔpAm7Gá!Am2Y9/;p3QÚ�9;mA85p3QA89FÕoá ÛY;m9WßK3QØ?@QÝo9�Ó�@B5�A82Y9�Ôp@BÖY;8Am58Û4ÔpAm×:@oÖK@QÓ�ÞY58@)Ùp9WÔpAm×GÝB9Þ?@o7:áD2Y9WßD5p3Q7[×:ÖDÝo3Q5m×�3QÖDA8;-Ó�58@oÚ 7G@YÔ�367�A85m×G2�9WßD5�367[ÝB9�58Am×�Ô#9�;W=

�Ê»%� ��Ã�ÄQÃo�ÉDÆWÉDÄQ¾�½FÉYÇ<�·�"!)ÉYÐ6Æò½��áDÞ?@oAm2Y9�;8×:;�9pâYA89�ÖY;m×:@oÖ 243Q;�A8×:7:7�ÖY@QC Ø?9�9�Öæ36ÞYÞY7:×:9Wß�@BÖY7:áåAm@å5m×GÕB×�ß�@oØoÙ#9WÔpA8;)=k>-3Q5p3QÚ�à9�Am9�58×:;89)ß @BØoÙp9WÔpAm;ÏÔ�3QÖ�Ø?9Ï2?3QÖ4ßD7:9WßK9)3Q;8×:7:áK×^Ó�A82�9�á�;�36A8×:;|Ó�á�Ôp9�5mA�36×GÖ�C�9�7:7�ßD9�<4ÖY9)ß Ôp@BÖDà;8Am5�36×GÖDAm;W=[>�×GÕB×�ßÏ@BØoÙp9WÔpAm;589��oÛ�×G5m9/Am2Y9�×:ÖDÝo3Q58×�36Ö�Am;�ÛY;89)ßK×GÖ�9pâYA89�ÖY;m×:@oÖKA8@!A�36Òo9/3�;8×:ÖYÕB7:9Ýo3Q7:ÛY9!ú�Ú�@YßDÛY7:@!ÖY@o×:;89)û87ÊÞ43Q5p3QÚ�9�Am9�58×:;89)ß�@oØoÙ#9WÔpA8;�C�×:7:7�ÕB9�ÖY9�5p3Q7:7:áå2?3)Ýo9�A82�9Ï×:ÖDÝo3Q58×�36Ö�Am;A�36ÒD×GÖ�Õ/3�5�36ÖYÕo9�@6Ó Ýo367:ÛY9�;WïD3QÖ?ß�;8@7:@oÖ�Õý36;036ÖDáEÙp@o×:ÖDA-×:Ö�Ýo3658×�3QÖDAÊÓ¬367G7:;-C�×:A82Y×:Ö�A82Y9�5�36ÖYÕo9×:A�ÚÏ3)áØ?9�2Dá�Þ?@oAm2Y9�;m×G;m9Wß�Am243QA�3�Ô#9�58Ap3Q×:Ö�Þ43Q5p3QÚ�9�Am9�58×:;m9Wß�@BØoÙp9WÔpA�Ôp7�3Q;m;�×:;�ÞY589F;89�ÖDAW=BÑ�2Y×:;3QÞ�ÞY58@D3oÔm2 C�×:7:7�Ø49Ú�@B;8A�9���9WÔpAm×:Ýo9�C�2Y9�Ö Am2Y9EÙp@B×GÖDA�×:ÖDÝo3Q5m×�36ÖDA8;�Ô82?3QÖYÕB9Ú�@oÖY@BA8@BÖY×�Ô�3Q7:7:áC�×:A82�5m9�;8Þ?9WÔpA!Am@ A82�9 Þ43Q5p3QÚ�9�Am9�58×:;p3QA8×:@BÖæúÅÓ�@o5�9pâ43QÚ�ÞY7:9oïÊÓ�@o5+3KÞ?3Q×:5�@QÓ;�Ô#×G;m;8@B58; 3QÖDáÙp@B×GÖDA�×:ÖDÝo3Q5m×�3QÖDA[Ú�9W36;8ÛY5m9Wß�Ø?9�A|C�9�9�Ö!A82�9�2436Ö4ßD7:9�;�;m2Y@oÛY7�ß�Ôm2436ÖYÕo9�Ú�@oÖY@BA8@oÖ�×�ÔF3Q7:7:á�C�×:Am2589F;8Þ?9WÔpAÏAm@åAm2Y9+36ÖYÕo7:9�@6Ó�@oÞ?9�ÖY×:ÖYÕ�ûF=[Ñ�2�×G;�3QÞYÞY5m@�3BÔ82�×:;/3QÖ4367:@oÕo@BÛY;Am@ A82Y9�C03)áKA82?3QAü�5m×GÚ�;m@oÖ�A8589)3QA8;�Þ43Q5p3QÚ�9�Am9�58×:;p3QA8×:@BÖY;�×:Ö öG÷B÷pø8=

��ÖY9K×:Ö�Am9�589F;8A8×:ÖYÕ�Ô�36;89�@6Ó¯3�Þ4365�36Ú�9�A89�5m×:;�3QAm×:@oÖ 243Q;!Ø?9�9�Ö ÖY@BA89WßgØDá=&ÿ@�@BÖY;Wïè#ë�Qé�¼�ö���lFø8ïQC�2Y9�5m9�A82Y9[Ù#@o×:ÖDA[×:ÖDÝo3Q58×�36Ö�AÊA�36Òo9�;E3�;m×GÖ�Õo7:9EÝo367:ÛY9o=Q1�@oÖY;m×�ßD9�5�Am2Y9�A�36;8Ò@6Ó 5m9WÔp@oÕ6àÖY×:;8×:ÖYÕ�@oØoÙp9WÔ#A8;�Ôp@BÖ�Ap3Q×:ÖY×:ÖYÕ�Þ436×G5m;E@6Ó�Ôp@oÞ�7�36Ö43Q5�ú�ØYÛYA�ÖY@BÖDà¬5m×:Õo×�ßD7:á�@o58×:9�ÖDAp3QA89)ßYû�Am58×�3QÖ�Õo7:9�;ÛYÖ4ßO9�53 � ÖY9ßD×:;8Am@o5mA8×:@oÖY;)=��Ö6<4Ö4ßD×:ÖYÕÏ36ÖDáÏA85m×�3QÖYÕB7G9�×:Öÿ3�;pÔp9�ÖY9�C�9ÚÏ3)á�2Dá�Þ?@oAm2Y9�;m×G;m9A82�9ÏÞY5m9�;89�Ö?Ôp9 @QÓ�;mÛ4Ôm2þ36Ö�@oØoÙp9WÔ#AW=Ø��2Y9�Ö�A|CE@!A85m×�3QÖYÕB7G9F;243)Ýo9�Ø49F9�Ö 7:@YÔ�3QAm9Wß�3Ùp@B×:Ö�A×:ÖDÝo3Q58×�36Ö�A(@QÓ[A82�9�5�36A8×:@@6Ó�A82�9�A85m×�3QÖYÕB7G9�36589W36;�Ô�3QÖ�Ø49�Ú�9W3Q;mÛY589)ß�=YÑ�2Y×:;�Ap3QÒB9�;�3�ÛYÖY×��BÛY9Ýo3Q7:ÛY9�×:Ö4ßD9FÞ49�Ö?ßD9�ÖDA�@QÓ�Am2Y95m9�7�3QA8×:ÝB9�Þ?@o;m×:A8×:@oÖY;�@6Ó�A82Y9Am58×�3QÖ�Õo7:9�;�3QÖ?ß+367:7G@QC�;�3�Ó�ÛY5mA82Y9F57:9�Ýo9F7[×:Ö4ßD9pâY×:ÖYÕ�A8@�Ø?9�;8ÛYØY;mA�36Ö�Am×�3QA89)ß�=

�Ê»>� 2�ÍBoX�-¾�¿-¾�¿-ÀKÁ�¿[ÂDÃYÄQ¾ÅÃY¿[ÆQ½ m ÄQÍBo i�¾@?�É�ÄQÉD¿ÊÆ,25-ÅÃ4½W½FÉY½Ñ�2Y9�9pâ43QÚ�ÞY7:9�;�Õo×:Ýo9FÖ ×:Ö+Am2Y×:;�Þ436Þ49F5ý367:7G@QC A82�99pâYA89�Ö�;8×:@oÖK@QÓE2DáDÞ?@oA82�9�;89�;�C�×:A82�×GÖ�A82Y9Ó�@B7G7:@QC�×:ÖYÕ!A82�589�9åÔ#7�36;8;m9�; ?�3Q7:Õo9�Ø�5�3Q×�Ô"7Øn ÔpÛ�58Ýo9F; 7E36Ö4ß ú�;89�Ú�×�û¬à ßD×���9�589FÖ�Am×�3Q7�Ú�9W36;8ÛY5m9�;W=��58@oÚ A82Y9!C�3)áåAm243QA�A82Y96n Ô#ÛY58ÝB9�;ÏC�9�589!5m9WßDÛ4Ôp9)ß A8@�3QÖ 3Q7:Õo9�Ø�5�3Q×�Ô�Ôp@oÖ�<?ÕoÛY5p3QA8×:@BÖÓ�@B5�A82�9¯Ôp@BÚ�ÞYÛYAp3QA8×:@BÖ+@6Ó�A82Y9�Ùp@o×:ÖDA�×:ÖDÝo3Q58×�36Ö�Am;�CE9�;89�9�A82436AWï?×:Ö!ÞY5�3BÔpA8×�Ôp9oïã2�áDÞ?@oAm2Y9�;89F;Ô�36Ö+Ø?9�Ó�@o5mÚ�9Wß�Ø?9�A|CE9F9�ÖåßD×���9�589�ÖDA�Ôp7�36;8;89F;W=Yù|Ö%Ó¬3oÔ#AWïD×:AE×:;�7:×GÒB9�7:á/Am243QA�A82�9�@BÖY7:á/C�3)á�A8@589)Ôp@QÝo9�5�3�Û�;89pÓ�Û�7O�BÛ436Ö�Am×:A|á+@6ÓEÕo9F@oÚ�9�Am58×�Ô�ßY3QAp3%Ó�58@BÚ 3Ï;pÔp9�ÖY9�C�×:7G7ÊØ49�ØDáåÔ#@oÚ�ØY×:ÖY×:ÖYÕÔpÛY9F;�×:Ö�A82Y×:;�ÚÏ3QÖ�ÖY9�5W=

Page 17: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

��ÐBA�¿�Í�C·-�ÉYÇÊÀ?ÉFo�ÉD¿ÊÆò½Ñ�2Y9�36ÛYA82�@o5�C�@oÛY7�ß�7:×GÒB9�A8@9#âOÞ�589�;m;�A82436ÖYÒD;-Ó�@o5�ßD×:;�ÔpÛY;m;8×:@oÖ�;EC�×:A82,#�3)ÝD×�ßE��@o58;máDA82[ïEDo@D9&!Û�Ö4ßDáDïD<�Ö4ßD5m9�CGF?×G;m;89�5mÚÏ3QÖå36Ö4ßH&ÿ×GÒB9rN�5p3oßDáD=DÑ�2Y9�;8ÛYÞ�Þ4@B58A�@6ÓÈü�9FÖY9�5�367�ä-7:9WÔ#A858×�Ô�×:;367G;m@¯3BÔmÒ�Ö�@QC�7G9)ßDÕo9WßãïY3Q;�C�9�7:7[3Q;�A82?3QA�@QÓEä\�A>�>�ù|Ñæ36Ö4ß�A82Y9Eº(���=

I YKJ8YÊ´Y[²�¸0YH|dWxMLzE�|q {%NP)R�N4b�x7O|z(�`on���`Q�Wr { \�r�`Qq|��PF�Èe ]�rF`�r { jQnpq|�pN P �$�ϱ M(n � r { q|R�n�`Qq�PF�RQ�rFq|lonpRrFq�\Gkp�pNSYZB`o_���`o�|q�\:q|Zoq|n�PF�[­�n�kmlo`BP�]:PWa)s)NOj6}�np_Bn�`�N4d�V)VWU6xvQx�XÊP�]~]Gnp�pNOL0x�r�`B_ÏJ�r#\G`YNDL�xTOmL-npk�P)a)`Q\G��\:`oa/rF`o_HS�PQk�r�q�\:`oae�r { q�\�r#]^]Gs�U(\G��\:�Q]Gn�f��Q«|npkpq|� Þ ­�lonSYPQk�r#]^c íBn�rFq|Z { nmc íBPQkpZo��Q�n�q|lBPQ_YN P·�9V �W� N6UÊP�]�xYd)NOt(PoxDUQN � xªS�X#c¬i)vQN?d#V)i)vQxUQx�X { r�_BsWNYQ�xTO8J { \Gq|n { \�rÈ��P { L-n �o{ np�|np`Qq8rFq�\GP)`/PF� jQlDr � n)N P�\:`·à ©o¥ ¢ � ¢ ����Z ¢Q¡ �D¦:�D¤ [�¦~£�¦   ��±XÊn�k ® NO�(P � n�r�`B_¯LÈPW�|np`Q��nm]G_�np_6\Gq|P { �pN�z�k�r�_Bn�R�\:k�e { np�|�pN4d�V)iWU6x\ x�J�r { ]G�|�|P)`YN�jDx O8e { P�«|npk�q�\:�Wnm]:s���`Q�Wr { \�rF`Qq+M(npkpPWR � PW��\:q�\GP)` P��¯e ]�rF`�r { jQlDr � np�pN P \G`,ûªvQd^ý�N� xªv üBXpc|v�X)UQN�d�V)VWv6xSQx�I�q|q�\:`oa)n { N4H�x^]Qx�O)S?r { a)n�-\:n { r { k8l6\Gk�r#]�f��Q«|n�kpq�L-npkpPWa)`Q\:q�\GP)`Ïy���\:`oa_SO\G� { r { \:n���PF�Èe�r { r�R�cnpq|n { \@`pn�_HQ�PQ_Bnm]ãj6Zo�Qc|e�r { q|�pN P/e { PQkpnpnp_Q\G`BaW��JaU�e[L�i)i6N � x U)vpc \ d)N4d�VWi)i6xüQxhíBP { �|sQq|l�NOM�x z�x^N6Q�Zo`B_os)Nb]Qx Sãx^Ndc�\G�|�|n { Rr�`�N�z�x e?x~NòJ-PQnm]:loPBN�J�x^No�(nm]^]Gn { NQz�x6rF`o_�L-P)q|lQ}-n8]~]�NJ�x z�x7O ��`Q�Wr { \�rF`Qq�M(n��|k { \ � q|P { ����P { Upc¬M f��Q«|npkpq0L-npkpP)aW`6\Gq�\GP)` r�`B_+e?P)�|n)N P·�^�Ø�H� � ��¢ �o£��eFÖ Z � ± UÊP�]�xYd#U6NYt�PBxYd�wQN � xªV�X6d8c|VWV6dWNYf�kpq|PW�Dn { d#V)VQd)xXQx�X-r {|{ npq|qpN�I-xªX�x~NEe�rpsQq|P)`YN�e?x Q�xErF`o_�X { \^]~]�NfQ�xª��xgOmJ-P)`Qq { \G�oZBq�\GP)`o��q|P�q|lon!­�lonpP { s PF�e { PF«¬npkpq�\G�)n���`Q�Wr { \�rF`Qq|����P { J-Z { �)np��\:`/­(}�P�r�`B_�­�l { npn�MÈ\GR�np`o��\:PW`B�pN P�e { PQkpnpnp_Q\G`BaW��dBhjiM-z�L�eDz(c¬I[jBe[L-��­<kÏP {|® �|loP � PW`���`Q�)r { \�r�`Bk�n)N � x U)i�X#c \ vWS6NlQ�r { k8l!d�V)VQd)xiQx�Xã\G`Q��P { _YN�­�xªf�x'O ��`6��n {|{ \:`oa jQZ { �ÅrFkpnp�� { P)R���RrFaWnp�pN PRÖh� ��¦ µ ¡ ¦ ¢)�¸� ����¤ �:� ¦ ¨ ¤8� ¡ ¤¤± U[PF]�x�d%XQN� xªvWw)Spc|v \B\ N�d�V)iQd)xVQx�Xã\G`Q��P { _YND­�x f�xDr�`B_HSYnp�)\Gq|qpNB­�x jOxTOm�ZDr���\~c���`Q�Wr { \�r�`Qq|� Þ ­(lonpP { s�r�`B_ÏI�h � ]�r�`Dr�q�\:PW`�N Pe { PFckpn�np_6\G`oa�MEr {|� r��|ynk N � x i6d#V#c¬i)vWV6N�d�VWV)UQxd�wQx�J�rF`o`Qso]Qx íÊx$O|z J-P)R � ZBq8r�q�\:PW`Drp]4z �o�B{ PòrFk8l�q|P�I�_BaWn�M�npq|npkpq�\GP)`YN P/�^�H�Ø� � ��¢ �B£�� e�Ö Z � ±U[PF]�x�i6NYt�PBx~ü6N � x üBXWV#c ü)VWi6N�d#V)i�üQxd)dWx�H { \GR��|P)`YNKk xªI-xpS�x0q�©�× ¤ ¡ �W�-¤ ¡m 8¨ �D¦:��¦   � © ªHr   ¥���©���¤ � ±5���D¤ �  )� ¤   §ts�¤   ¥�¤8� � ¦ ¡ r   �B§£�� ��¢ ¦:���:£@± Q���­þe { np�|�pN4d�VWV)w6xd�vQxu]Wr�kpP)�o�pN4M�x k�xTOmj � rFkpn�I �ýkm\:n�`Qq�UWM<Q�PQ_onm][��`o_Bn�h)\:`oaBN Pe { PQkpnpnp_Q\:`oa)�0JaU�e[L(VWv6N � x \ UWV#c\�\B\ N�d#V)VWv6x

d�UQx�b�n { n�`�NOM�x^NDjQZo� { r�lBR�PW`6\�r6Nv]Qx�rF`o_�J-PQP � n { NYM�x X(xTOmL-PW�BZo�|qEf��6«¬npkpqEL-npkpP)aW`6\Gq�\GP)`�X�rF�|np_PW`���R � ]^\Gkm\:q�z(]Ga)np� { r#\Gk-J-Z { �)np� rF`o_�j6Z { ��r�kpnp�pN P�e { PQkpnpnp_Q\:`oa)� JaU�e[L(VWv6N � xpXWV6d8c2XWV \ NQd�V)VWv6xd \ x�S4rFR�_�rF`YN?u�x~N�jQkmlQ}Èr { q2`)NK]Qx ­�xDr�`B_tkÏPF]^���|PW`�N4��x^]QxTOmf��Q«|n�kpq�L-npkpPWa)`Q\:q�\GP)`��Qs/z(�`on���`Qc�Wr { \�rF`Qq'Q�rFq|k8l6\G`oaBN Pe { PQk�npnp_Q\:`oa)�0JRU0eÊL�iWi6N � x U)U)Spc¬U \B\ N�d�VWi)i6xd�SQx�SYPF}�n)NEM�x H�x0e ¤ ��¡ ¤ ����© ¢)��qf�G¨Q¢ �D¦�¹ ¢ �Ŧ   � ¢ ���<[�¦^£�© ¢)� ��¤ ¡8 8¨ ��¦:��¦   �C± b(]GZQ}-n { z�k#rF_onpR�\Gke�ZB�Q]^\:�|lon { �pN�d�VWi)SQxd8üQx�SD\:ZYNK]Qx~NvQ�Zo`o_Bs)N"]Qx Sãx^NíBP { �|sQq|l�N M�x z�x^N$cB\G�|�|n { RrF`YN4z�x4rF`o_+LÈPWq|lQ}-nm]^]�N4J�x z�x�OmI?�km\Gnp`QqL-npkpPWa)`Q\:q�\GP)`ÏPF��L-PWq8rFq�\GP)`�r#]^]:s¯j6sQR�R�npq { \:k�jQZ { ��rFkpn���rF`o_+j6q { rp\:aWlQq���P)R�PWa)np`onpPWZB��H�np`Qcn { rp]~\w`pnp_¯J-s)]~\G`B_on { �pN Pe { PQkpnpnp_Q\:`oa)�0JaU�e[L(VWU6N � x^d�vWU#c8d�vWi6N�d�VWV)UQxd%XQx�Q�r {|{ NYM�x [�¦~£�¦   ��± í { n�npRrF`YN?d#V)iWv6xd�iQx�Q�rpsQ��rF` ® N[jOx>]Qx"O|­�lBn�e { P�«|npk�q�\:�Wn�H�npPWR�npq { s/PF��z�R��6\Ga)ZoP)Zo��jQZ { �ÅrFkpnp�pN Pxeæ�� �¡ �K��� �Y �¡ ��Y  �F�"� N�jQn { \Gnp��z�N6UÊP�]�x�UWU)v6N � x^dmc \ X6N?d#V)VWw6xd�VQx�Q�PWl { N�L�x�r�`B_yQ�P { \:`YN"SãxROmL-nm]�rFq�\G�)n/e?PW��\:q�\GP)`Q\:`oa�� { PWR H�n�P)R�npq { \Gk��`Q�Wr { \�rF`Qq|�pN PÏe { PFckpn�np_6\G`oa)��JaU0eÊL�V6dWN � x~d#U)Vpcmd \B\ N?d�VWV6dWx

Page 18: University of Oxfordvgg/publications/1994/... · 2011-08-18 · Y÷mø8ï @oA82 95 C @o5mÒ ; C 2 9589 ×:ÖDÝo3Q5m× 3QÖDA8; 243)Ýo9Ø?99Ö Ôp@oÚ Þ ÛYA89Wß+Ó @o5 3 Ýo3Q5m×G9FA|áÏ@Q

v)wQx Q�PQP)`o�pN[­�x~N4e�r�ZQ}-nm]G�pN[IÈx^NvU-r�`!H�PQP�]�N"S�x�r�`B_åf�PW�|q|n { ]~\G`ok ® N4z�xROzU�\:np} � P�\:`Qq���`Q�Wr { \�r�`QqJ-lDr { rFkpq|n { \@`�r�q�\:PW`!PF�0f��Q«|npk�q|��JÈPWR � PW�|np_ PF�EM-\~�Yn { np`Qq�LÊ\GaF\G_ e�r { q|� Þ rtQ�rFq|lonpRr�q�\:k#r#]í { r�R�np}-P {|® N P\:` s�¤   ¥�¤8� � ª ¢ ���6�   �  )�^ 8¨ ª   § � © © ¥ ¢ �D¦ §  )� �)£^± U[PF]�x4S6x^NbU[n { �|q { r�nm]:n�`�N e?xrF`o_ÏMÈ\^]^]:np`YNFíÊxDnp_Q\Gq|P { �pN6k�P { ]:_ÏjQkm\Gnp`Qq�\�ìDk)N4d�VWV)U6xv6dWx Q�Zo`B_os)Nb]Qx SãxòrF`o_tcB\G�|�|n { Rr�`�Noz�x e?x s�¤   ¥�¤8� � ¦ ¡f� ��� ¢"� ¦ ¢ � ¡ ¤(¦%�{r   ¥���©���¤ � [ ¦~£p¦   ��± Q���­e { np�|�pN?d#V)V)vQxv)vQx�tÈ\Gnm]G�|np`YN�SãxlO z�Zoq|P)RýrFq|np_�H�Z6\G_�rF`okpn�PF�|UÊnplQ\Gkm]:n���ZB��\G`BafU(\G��\:PW`�rF`o_e { PF«|n�kpq�\:�Wn-��`Q�Wr { \�r�`QqQ�r {|® \G`oaBN PEÖ ©��   ¥ ¢ ��¦ ¡8¢ ± U[PF]�xov \ N � x~d#U)S#c8d \ i6N�d#V)iWi6xv)UQx�L-P)q|lQ}-n8]~]�NoJ�x z�x~NdcB\:�|�|n { RrF`YNDz�x~N�íoP { �|sQq|lYNDM�x z�xorF`o__Q�ZB`o_os)Nb]Qx SãxvO8J�rF`oP)`Q\:k�rp]¸í { rFR�n����P { e?]�rF`�r { f��Q«|npkpqEL-npkpPWa)`Q\:q�\GP)`YN P/e { PQkpnpnp_Q\G`BaW��I[J(JaU0v6N � x X)S�X#c�XBXWv6N4d�V)VWv6xv \ x�L-P)q|lQ}-n8]~]�N�J�x z�x^NíBP { �|sQq|l�NãM�x z�x^Nvc�\G�|�|n { Rr�`�N z�x rF`o_MQ�ZB`o_os)Na]Qx Sãx7OmI�hQq { rFk�q�\:`oaÏe { P�c«|npk�q�\:�Wn���`6��P { RrFq�\GP)`�� { PWR j)\:`oaF]GnHU(\Gnp}���PF�ýU)M e?P�\:`Qq¯j6npq|�pN P�e { PQkpnpn�_6\G`BaW���|J�JaU \ N� xªS�X)U#c¬SWi)v6N�d#V)VWU6xv)SQx�L-P)q|lQ}-n8]~]�N�J0x z�xfq-©�× ¤ ¡ �0�-¤ ¡8 m¨ �D¦%�Ŧ   �J��� ��  © ¨ � � ��� ¢"� ¦ ¢ ��� � ���Q¤@�6¦%� ¨ ± ­�P+r �o� n�r { f�yEe?Nd�VWV \ x

v�üQx�j)\:`okm]�r#\ { NDM�x z�xorF`o_�X�]�r ® n)Noz�xTO|���|P � n { \:R�npq { \:k0t(P { Rr#]^\:�8r�q�\:PW`PF�[e?]�rF`�r { J-Z { �Wnp�pN P ��� NM(n � r { q|R�np`Qq�P���Iã`oaF\G`onpn { \G`Ba/jQkm\:n�`BkpnWNYf�h)��P { _�y(`Q\G�)n { ��\Gq�s)N�f�h)��P { _�N4d�VWV)U6xvBXQx�­[rFZo�Q\:`YNWH�x�r�`B_�J-PQP � n { NWM�xªX�x6Omf��Q«|n�kpq�L-npkpPWa)`Q\:q�\GP)`�X-r��|np_�P)` Q�PWR�np`Qqfî�P { z�]:aWnp� { rp\:k¤ï��`Q�Wr { \�r�`Qq|�pN P5�)} Z ����§j��rK,6~�3"ÿ|~�± �|XaQ ­�x>]QxBk+rFq|�|PW`/LÈn��|n�r { k8l�J-np`Qq { n)N6e x f�xòXÊP�h X)w \ Nu[P {|® q|P�}�`��(n8\:aWlQq|�pNYt(u�d�wWS)VWi6N�d�VWV6dWxv)iQx�­[rFZo�Q\:`YN�H�xfO zE`���R �o{ PF�Wnp_Kz�]:aWP { \Gq|lBR ��P { z�]:aWnp� { r#\Gk�J-Z { �Wn�r�`B_åjQZ { ��r�kpnÊí�\Gq|q�\:`oaBN Pe { PQkpnpnp_Q\:`oa)�E�|J�JaU \ N � x ü)S)ipc ü�ü)SQN�d�VWV)U6xv)VQx�U�rF` H�PQP�]�N�Sãx¯b�npR � n�`Dr�n { �pNÏe?x�r�`B_ f�P)�|q|n { ]^\:`ok ® N�z�xMO8LÈn�kpP)aW`6\Gq�\:PW` rF`o_ jQnpR�\^c

MÈ\^�Yn { n�`Qq�\�rp]���`Q�Wr { \�r�`Qq|�pN P/e { PQkpnpnp_Q\:`oa)�0JaU�e[L(VQd)N � x \ S \ c \ üWw6N?d#V)VQd)xU)wQx�k+r#sQ`on { Nòe?xªJ�x6O8I �ýkm\:n�`Qq�]:s0y(��\G`Ba���`Q�Wr { \�r�`Qq�­(lonpP { s(��P { Q�PQ_onm]~c¬X-r��|np_ Q�r�q|kmlQ\:`oaBN PEe { P�ckpnpn�_6\G`BaW��JaU�e[L�V6dWN � x \ X)U#c \ X)i6N4d�VWV6d)xU6dWx�kÏnm\:�|�pN[�8x�O8e { P�«|npk�q�\:�Wn���`Q�Wr { \�r�`Qq|��P���jQlDr � np�pN P e { PQkpnpnp_Q\:`oa)�¯M-z�L�eDz ��RrFaWn�y(`o_on { c�|q8rF`o_Q\:`oa k�P {|® �|lBP � N � x~dWd�vWS#c8d)d#U \ NYz �B{ \^][d�VWi)i6x

­�l6\G�Er { q�\Gkm]Gn�}�r�� �o{ PQkpnp�|�|n�_�Zo��\:`oa�q|lon S �p­ I+� Rr�k { P � rFk ® r�a)n�}-\:q|l_SbS4t�J�j��|q�s)]:n