14 research outputs found
Robust signatures for 3D face registration and recognition
PhDBiometric authentication through face recognition has been an active area of
research for the last few decades, motivated by its application-driven demand. The popularity
of face recognition, compared to other biometric methods, is largely due to its
minimum requirement of subject co-operation, relative ease of data capture and similarity
to the natural way humans distinguish each other.
3D face recognition has recently received particular interest since three-dimensional
face scans eliminate or reduce important limitations of 2D face images, such as illumination
changes and pose variations. In fact, three-dimensional face scans are usually captured
by scanners through the use of a constant structured-light source, making them invariant
to environmental changes in illumination. Moreover, a single 3D scan also captures the
entire face structure and allows for accurate pose normalisation.
However, one of the biggest challenges that still remain in three-dimensional face
scans is the sensitivity to large local deformations due to, for example, facial expressions.
Due to the nature of the data, deformations bring about large changes in the 3D geometry
of the scan. In addition to this, 3D scans are also characterised by noise and artefacts such
as spikes and holes, which are uncommon with 2D images and requires a pre-processing
stage that is speci c to the scanner used to capture the data.
The aim of this thesis is to devise a face signature that is compact in size and
overcomes the above mentioned limitations. We investigate the use of facial regions and
landmarks towards a robust and compact face signature, and we study, implement and
validate a region-based and a landmark-based face signature. Combinations of regions and
landmarks are evaluated for their robustness to pose and expressions, while the matching
scheme is evaluated for its robustness to noise and data artefacts
Human sound localisation cues and their relation to morphology
Binaural soundfield reproduction has the potential to create realistic threedimensional sound scenes using only a pair of normal headphones. Possible
applications for binaural audio abound in, for example, the music, mobile
communications and games industries. A problem exists, however, in that
the head-related transfer functions (HRTFs) which inform our spatial perception of sound are affected by variations in human morphology, particularly in the shape of the external ear. It has been observed that HRTFs
simply based on some kind of average head shape generally result in poor
elevation perception, weak externalisation and spectrally distorted sound
images. Hence, HRTFs are needed which accommodate these individual
differences. Direct acoustic measurement and acoustic simulations based
on morphological measurements are obvious means of obtaining individualised HRTFs, but both methods suffer from high cost and practical difficulties. The lack of a viable measurement method is currently hindering
the widespread adoption of binaural technologies. There have been many attempts to estimate individualised HTRFs effectively and cheaply using easily
obtainable morphological descriptors, but due to an inadequate understanding of the complex acoustic effects created in particular by the external ear,
success has been limited. The work presented in this thesis strengthens current understanding in several ways and provides a promising route towards
improved HRTF estimation. The way HRTFs vary as a function of direction is compared with localisation acuity to help pinpoint spectral features
which contribute to spatial perception. 50 subjects have been scanned using
magnetic resonance imaging to capture their head and pinna morphologies,
and HRTFs for the same group have been measured acoustically. To make
analysis of this extensive data tractable, and so reveal the mapping between
the morphological and acoustic domains, a parametric method for efficiently
describing head morphology has been developed. Finally, a novel technique,
referred to as morphoacoustic perturbation analysis (MPA), is described.
We demonstrate how MPA allows the morphological origin of a variety of
HRTF spectral features to be identified
Automated shape anthropometry
In medicine, ergonomics, the clothing Industry and many other areas
such as the design of 'g' suits for military aeroplane pilots and
protective clothing for chemical warfare, there is a requirement for the
accurate 3-D measurement of the size and shape of the human form.
To meet this need a novel whole body scanner has been designed
which is capable of measuring both the size and shape of people in a
non invasive socially acceptable manner. The scanner uses structured
light and an array of television cameras to view free standing subjects
while they are being rotated on an electrically driven turntable. The
accuracy and repeatability of the scanner is as good as trained
anthropometrists using traditional manual methods.
A computer program has been written which uses a cubic spline
interpolation method to edit and interrogate the data from the scanner
and arrange it in a shape matrix form. This is a new way of arranging
the data which allows for the 3-D average of several bodies to be
obtained and also for the comparison of one body with another. A
technique which is essential if 3-D survey work is to be undertaken.
Using master files which contain information from a data base of
previously scanned people and eight circumferential measurements it
is possible to re-create body forms of any size but which correspond to
the average shape for that size. The re-creation of body shapes from
eight circumferences is accurate enough for the manufacture of all but
the most close fitting garments but may be more useful in the future as
a replacement for somatotyping (physique classification). It is perfectly
possible to manipulate the eight circumferences to create body torsos of
almost any shape. Conversely a torso of almost any shape could be
defined by eight two digit numbers
A new method for generic three dimensional human face modelling for emotional bio-robots
Existing 3D human face modelling methods are confronted with difficulties in
applying flexible control over all facial features and generating a great number of
different face models. The gap between the existing methods and the requirements of
emotional bio-robots applications urges the creation of a generic 3D human face
model. This thesis focuses on proposing and developing two new methods involved
in the research of emotional bio-robots: face detection in complex background
images based on skin colour model and establishment of a generic 3D human face
model based on NURBS. The contributions of this thesis are:
A new skin colour based face detection method has been proposed and
developed. The new method consists of skin colour model for skin regions
detection and geometric rules for distinguishing faces from detected regions. By
comparing to other previous methods, the new method achieved better results of
detection rate of 86.15% and detection speed of 0.4-1.2 seconds without any
training datasets.
A generic 3D human face modelling method is proposed and developed. This
generic parametric face model has the abilities of flexible control over all facial
features and generating various face models for different applications. It includes:
The segmentation of a human face of 21 surface features. These surfaces have
34 boundary curves. This feature-based segmentation enables the independent
manipulation of different geometrical regions of human face.
The NURBS curve face model and NURBS surface face model. These two
models are built up based on cubic NURBS reverse computation. The
elements of the curve model and surface model can be manipulated to change
the appearances of the models by their parameters which are obtained by
NURBS reverse computation.
A new 3D human face modelling method has been proposed and implemented
based on bi-cubic NURBS through analysing the characteristic features and
boundary conditions of NURBS techniques. This model can be manipulated
through control points on the NURBS facial features to build any specific
face models for any kind of appearances and to simulate dynamic facial
expressions for various applications such as emotional bio-robots, aesthetic
surgery, films and games, and crime investigation and prevention, etc
Improved facial feature fitting for model based coding and animation
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Vector offset operators for deformable organic objects.
Many natural materials and most of living tissues exhibit complex deformable behaviours that may be characteriseda s organic. In computer animation, deformable organic material behaviour is needed for the development of characters and scenes based on living creatures and natural phenomena. This study addresses the problem of deformable organic material behaviour in computer animated objects. The focus of this study is concentrated on problems inherent in
geometry based deformation techniques, such as non-intuitive interaction and difficulty in achieving realism. Further, the focus is concentrated on problems inherent in physically based deformation techniques, such as inefficiency and difficulty in enforcing spatial and temporal constraints. The main objective in this study is to find a general and efficient solution to interaction and animation of deformable 3D objects with natural organic material properties and constrainable behaviour. The solution must provide an interaction and animation framework
suitable for the creation of animated deformable characters. An implementation of physical organic material properties such as plasticity, elasticity and iscoelasticity can provide the basis for an organic deformation model. An efficient approach to stress and strain control is introduced with a deformation tool named Vector Offset Operator. Stress / strain graphs control
the elastoplastic behaviour of the model. Strain creep, stress relaxation and hysteresis graphs control the viscoelastic behaviour of the model. External forces may be applied using motion paths equipped with momentum / time graphs. Finally, spatial and temporal constraints are
applied directly on vector operators. The suggested generic deformation tool introduces an intermediate layer between user interaction, deformation, elastoplastic and viscoelastic material behaviour and spatial and temporal constraints. This results in an efficient approach to
deformation, frees object representation from deformation, facilitates the application of constraints and enables further development
Actas do 12º Encontro Português de Computação Gráfica
Actas do 12º Encontro Portugês de Computação Gráfica, Porto, 8-10 de Outubro de 2003O Encontro Português de Computação Gráfica teve lugar nesse ano 2003, naquela que foi a sua 12ª edição, no ISEP – Instituto Superior de Engenharia do Porto, entre os 8 a 10 de Outubro. O 12º Encontro Português de Computação Gráfica (12EPCG) veio no seguimento de encontros anteriores realizados anualmente e reuniu investigadores, docentes e profissionais nacionais e estrangeiros, que realizam trabalho ou utilizam a Computação Gráfica, Realidade Virtual e Multimédia, assim como todas as suas áreas afins, no sentido de
permitir a divulgação de projectos realizados ou em curso e fomentar a troca de experiências e a discussão de questões relacionadas com a Computação Gráfica em Portugal, entre as comunidades académica,industrial e a de utilizadores finais. Este é o livro de actas do 12EPCG.Fundação IlÃdio PinhoFC