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Publications sur Higher-order actif contours
Résultat de la recherche dans la liste des publications :
Thèse de Doctorat et Habilitation |
1 - Phase fields for network extraction from images.
A. El Ghoul. Thèse de Doctorat, Universite de Nice - Sophia-Antipolis, septembre 2010.
Mots-clés : Shape prior, Higher-order actif contours, Champ de Phase, Stability analysis, Directed networks, river extraction.
@PHDTHESIS{elghoul10c,
|
| author |
= |
{El Ghoul, A.}, |
| title |
= |
{Phase fields for network extraction from images}, |
| year |
= |
{2010}, |
| month |
= |
{septembre}, |
| school |
= |
{Universite de Nice - Sophia-Antipolis}, |
| url |
= |
{http://tel.archives-ouvertes.fr/docs/00/55/01/34/PDF/ThesisMunuscript2010_EL_GHOUL.pdf}, |
| keyword |
= |
{Shape prior, Higher-order actif contours, Champ de Phase, Stability analysis, Directed networks, river extraction} |
| } |
Résumé :
Cette thèse décrit la construction d'un modèle de réseaux non-directionnels (e.g. réseaux routiers), fondé sur les contours actifs d'ordre supérieur (CAOSs) et les champs de phase développés récemment, et introduit une nouvelle famille des CAOSs des champs de phase pour des réseaux directionnels (e.g. réseaux hydrographiques en imagerie de télédétection, vaisseaux sanguins en imagerie médicale). Dans la première partie de cette thèse, nous nous intéressons à l'analyse de stabilité d'une énergie de type CAOSs aboutissant à un ‘diagramme de phase'. Les résultats, qui sont confirmés par des expériences numériques, permettent une bonne sélection des valeurs des paramètres pour la modélisation de réseaux non-directionnels.
Au contraire des réseaux routiers, les réseaux hydrographiques sont directionnels, i.e. ils contiennent un ‘flux' monodimensionnel circulant dans chaque branche. Cela implique des propriétés géométriques spécifiques des branches et particulièrement des jonctions, propriétés qu'il est utile de traduire dans un modèle, pour l'extraction de réseaux. Nous développons donc un modèle de champ de phase non-local de réseaux directionnels, qui, en plus du champ de phase scalaire décrivant une région par une fonction caractéristique lisse et qui interagit non-localement afin que des configurations de réseaux linéiques soient favorisées, introduit un champ vectoriel représentant le ‘flux' dans les branches du réseau. Ce champ vectoriel est contraint d'être nul à l'extérieur, et de magnitude égale à 1 à l'intérieur du réseau ; circulant dans le sens longitudinal des branches du réseau ; et de divergence très faible. Cela prolonge les branches du réseau ; contrôle la variation de largeur tout au long une branche ; et forme des jonctions non-symétriques telles que la somme des largeurs entrantes soit approximativement égale à celle des largeurs sortantes. En conjonction avec une nouvelle fonction d'interaction pour le champ de phase scalaire, le modèle assure aussi une vaste gamme de valeurs des largeurs stables des branches. Ce nouveau modèle a été appliqué au problème d'extraction de réseaux hydrographiques à partir d'images satellitaires très haute résolution. |
Abstract :
This thesis describes the construction of an undirected network (e.g. road network) model, based on the recently developed higher-order active contours (HOACs) and phase fields, and introduces a new family of phase field HOACs for directed networks (e.g. hydrographic networks in remote sensing imagery, vascular networks in medical imagery). In the first part of this thesis, we focus on the stability analysis of a HOAC energy leading to a ‘phase diagram'. The results, which are confirmed by numerical experiments, enable the selection of parameter values for the modelling of undirected networks.
Hydrographic networks, unlike road networks, are directed, i.e. they carry a unidirectional flow in each branch. This leads to specific geometric properties of the branches and particularly of the junctions, that it is useful to capture in a model, for network extraction purposes. We thus develop a nonlocal phase field model of directed networks, which, in addition to a scalar field representing a region by its smoothed characteristic function, and interacting nonlocally so as to favour network configurations, contains a vector field representing the ‘flow' through the network branches. The vector field is strongly encouraged to be zero outside, and of unit magnitude inside the network; and to have zero divergence. This prolongs network branches; controls width variation along a branch; and produces asymmetric junctions for which total incoming branch width approximately equals total outgoing branch width. In conjunction with a new interaction function for the scalar field, it also allows a broad range of stable branch widths. The new proposed model is applied to the problem of hydrographic network extraction from VHR satellite images, and it outperforms the undirected network model. |
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2 Articles de conférence |
1 - A phase field higher-order active contour model of directed networks.
A. El Ghoul et I. H. Jermyn et J. Zerubia. Dans 2nd IEEE Workshop on Non-Rigid Shape Analysis and Deformable Image Alignment, at ICCV, Kyoto, Japan, septembre 2009.
Mots-clés : Geometric prior, Forme, Higher-order actif contours, Champ de Phase, Directed networks.
Copyright : ©2009 IEEE.
@INPROCEEDINGS{ElGhoul09b,
|
| author |
= |
{El Ghoul, A. and Jermyn, I. H. and Zerubia, J.}, |
| title |
= |
{A phase field higher-order active contour model of directed networks}, |
| year |
= |
{2009}, |
| month |
= |
{septembre}, |
| booktitle |
= |
{2nd IEEE Workshop on Non-Rigid Shape Analysis and Deformable Image Alignment, at ICCV}, |
| address |
= |
{Kyoto, Japan}, |
| url |
= |
{https://hal.inria.fr/inria-00409910}, |
| pdf |
= |
{http://hal.inria.fr/docs/00/40/99/10/PDF/nordia09aymenelghoul.pdf}, |
| keyword |
= |
{Geometric prior, Forme, Higher-order actif contours, Champ de Phase, Directed networks} |
| } |
Abstract :
The segmentation of directed networks is an important
problem in many domains, e.g. medical imaging (vascular
networks) and remote sensing (river networks). Directed
networks carry a unidirectional flow in each branch, which
leads to characteristic geometric properties. In this paper,
we present a nonlocal phase field model of directed networks.
In addition to a scalar field representing a region
by its smoothed characteristic function and interacting nonlocally
so as to favour network configurations, the model
contains a vector field representing the ‘flow’ through the
network branches. The vector field is strongly encouraged
to be zero outside, and of unit magnitude inside the region;
and to have zero divergence. This prolongs network
branches; controls width variation along a branch; and
produces asymmetric junctions for which total incoming
branch width approximately equals total outgoing branch
width. In conjunction with a new interaction function, it
also allows a broad range of stable branch widths. We
analyse the energy to constrain the parameters, and show
geometric experiments confirming the above behaviour. We
also show a segmentation result on a synthetic river image. |
|
2 - Phase diagram of a long bar under a higher-order active contour energy: application to hydrographic network extraction from VHR satellite images.
A. El Ghoul et I. H. Jermyn et J. Zerubia. Dans International Conference on Pattern Recognition (ICPR), Tampa, Florida, décembre 2008.
Mots-clés : Phase diagram, Higher-order actif contours, Forme, river extraction.
@INPROCEEDINGS{ElGhoul08b,
|
| author |
= |
{El Ghoul, A. and Jermyn, I. H. and Zerubia, J.}, |
| title |
= |
{Phase diagram of a long bar under a higher-order active contour energy: application to hydrographic network extraction from VHR satellite images}, |
| year |
= |
{2008}, |
| month |
= |
{décembre}, |
| booktitle |
= |
{International Conference on Pattern Recognition (ICPR)}, |
| address |
= |
{Tampa, Florida}, |
| url |
= |
{https://hal.inria.fr/inria-00316619}, |
| pdf |
= |
{http://hal.inria.fr/docs/00/31/66/19/PDF/icpr08aymenelghoul.pdf}, |
| keyword |
= |
{Phase diagram, Higher-order actif contours, Forme, river extraction} |
| } |
Abstract :
The segmentation of networks is important in several imaging domains, and models incorporating prior shape knowledge are often essential for the automatic performance of this task. Higher-order active contours
provide a way to include such knowledge, but their behaviour can vary significantly with parameter values: e.g. the same energy can model networks or a ‘gas of circles’. In this paper, we present a stability analysis
of a HOAC energy leading to the phase diagram of a long bar. The results, which are confirmed by numerical experiments, enable the selection of parameter values for the modelling of network shapes using the energy.
We apply the resulting model to the problem of hydrographic network extraction from VHR satellite images. |
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