The Automatic Generation of 3D Caricatures from a single Facial Photograph Lyndsey Ann Clarke

231 Pages·2009·47.96 MB·English

The Automatic Generation of 3D Caricatures
from a single Facial Photograph
Lyndsey Ann Clarke
A thesis submitted to the University of Wales in fulfilment
of the requirements for the Degree of Doctor of Philosophy.
Department of Computer Science
Swansea University
Spring 2009
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I dedicate this thesis to my family and to all the those who have encouraged
and supported me throughout my life.
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Abstract
Caricatures are a common form of humourous visual art, appreciated by or-
dinary people and found everyday in newspapers, on the internet, and on the
artcornersinculturecitiessuchasLondonandParis, whereitisquitecommon-
place to see caricaturists sketching passers-by. The aim of caricatures are to
create amusing artistic portraits of subjects by exaggerating their noticeable
features, whilst maintaining the likeness to their original visual identity. The
art of drawing caricatures is a combination of observational, creative and artis-
tic abilities, and each artist seems to have their own preferable style of drawing
caricatures.
During this research it has been identified that different caricatures drawn
by the same artist often exhibit a similar ‘deformation style’, in terms of the
varyinglevelsofexaggerationappliedtodifferentfacialfeatures. Aninteresting
technical challenge is therefore whether one can capture the essence of such
a style from a hand-drawn caricature and encode it so that it can be used
to produce computer-generated caricatures automatically for various different
subjects.
In this thesis, the author proposes a novel technique for capturing such
‘deformation styles’ from 2D hand-drawn caricatures and for applying the cap-
tured styles to create new 3D caricature models. The core of this technique
is a ‘physics-inspired’ pseudo stress-strain model developed in this work. This
model allows us to associate facial features with virtual materials, and to use
the physical properties of the materials to encode captured deformation styles.
A captured style is thus represented by a collection of virtual materials that are
stored in a template, which can then be applied to the 3D model of a subject in
conjunction with a force. This technique has been implemented in a prototype
system for computer-assisted generation of 3D caricatures from an input facial
photograph. In addition to automatic style capturing and caricature genera-
tion using style templates, the system also provides more creative users with
interactive facilities to assign virtual materials to features and to experiment
with different force levels. This thesis includes a collection of results, demon-
strating that the developed technique is intuitive and expressive. With such
a technique, ordinary people, who are perhaps with limited artistic skill and
prior knowledge on caricature generation, can now have the opportunity to
express their creativity and possess the tools to create caricatures themselves.
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Declaration
This work has not been previously accepted in substance for any degree
and is not being concurrently submitted in candidature for any degree.
Signed ............................................................ (candidate)
Date ............................................................
Statement 1
This thesis is the result of my own investigations, except where otherwise
stated. Other sources are acknowledged by footnotes giving explicit references.
A bibliography is appended.
Signed ............................................................ (candidate)
Date ............................................................
Statement 2
I hereby give my consent for my thesis, if accepted, to be available for
photocopying and for inter-library loan, and for the title and summary to be
made available to outside organisations.
Signed ............................................................ (candidate)
Date ............................................................
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Acknowledgments
I wish to thank my parents and family who have always had faith in my
abilities and have provided me with continuous support and guidance through-
out my education. I am exceedingly grateful for their continued advice, and
without their unfaltering support this research would not have been possible.
I would like to extend this thanks to all the family members who are no longer
with us, but are never forgotten. I would also like to give special thanks to
Paul for his encouragement, support and advice, and for always being able to
make me smile throughout times of difficulty during my studies.
I would like to thank my supervisor Prof. Min Chen for his continuous sup-
port and friendship throughout my studies, and I am extremely grateful for his
excellent guidance throughout my PhD. I would also like to thank my second
supervisor, Dr. Benjamin Mora for his beneficial assistance and suggestions,
and also Prof. Peter Townsend for his valuable contributions to my research.
I would finally like to thank all my friends and colleagues within the Com-
puter Science research community at Swansea University, for their friendship,
advice and and encouragement over the years. I would also like to take this
opportunity to thank the Department of Computer Science as a whole for pro-
viding me with the opportunity to undertake this research, and I would like
to thank all the staff and postgraduates who have inspired me and have made
this experience exceptionally enjoyable and rewarding.
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