1998
@phdthesis{Sta1998,
vgclass = {thesis},
vgproject = {cbir,invariance},
author = {Sergei Startchik},
title = {Geometric and Illumination Invariant Object
Representation: Application to Content-based Image Retrieval},
type = {{P}h.{D}. {D}issertation {N}o. 3009},
school = {University of Geneva},
address = {Switzerland},
month = {July},
year = {1998},
url = {http://cuiwww.unige.ch/\~startchi/PhD/},
abstract = {This work addresses several issues in the field of
computer vision. In particular, attention is focussed on the problem of
the representation of an object from its appearance in an image.
Several advances are proposed for the representation of planar shapes,
which are thus suitable for representing planar and faceted objects.
The representation developed is employed for content-based retrieval
from an image database.
The proposed projectively invariant description for groups of planar
disjoint contours as a simultaneous polar reparametrization of multiple
curves. Its origin is an invariant point and, for each ray orientation,
the cross-ratio of the intersections with the closest curves gives the
radius. The sequence of cross-ratio values for all orientations forms
a signature. With respect to other methods, this representation is
less reliant on individual curve properties, both for the construction
of the reference frame and for the calculation of the signature. At the
same time, this representation is local and integrates information from
multiple curves, guaranteeing robustness to curve discontinuities and
partial occlusions. Chromatic information is introduced into the
representation and offers two advantages. First, the representation
provides a more complete description of the shape and thus becomes more
discriminative. Secondly, the chromatic description is illumination
invariant under a diagonal chromaticity model and one more acquisition
variable is therefore removed. The proposed representation was
originally developed for planar shapes, but an extension has been
proposed and validated for trihedral corners. [truncated]},
}