Peter Horvath

Ancien Doctorant, INRIA / MAE / University of Szeged

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Dernières publications dans le projet Ariana :

A higher-order active contour model of a ‘gas of circles' and its application to tree crown extraction. P. Horvath et I. H. Jermyn et Z. Kato et J. Zerubia. Pattern Recognition, 42(5): pages 699-709, mai 2009. Mots-clés : Forme, Ordre superieur, Contour actif, Gaz de cercles, Extraction de Houppiers, Bayesian. @ARTICLE{Horvath09, author = {Horvath, P. and Jermyn, I. H. and Kato, Z. and Zerubia, J.}, title = {A higher-order active contour model of a ‘gas of circles' and its application to tree crown extraction}, year = {2009}, month = {mai}, journal = {Pattern Recognition}, volume = {42}, number = {5}, pages = {699-709}, url = {http://dx.doi.org/10.1016/j.patcog.2008.09.008}, pdf = {http://www-sop.inria.fr/members/Ian.Jermyn/publications/Horvathetal09.pdf}, keyword = {Forme, Ordre superieur, Contour actif, Gaz de cercles, Extraction de Houppiers, Bayesian} } Abstract : We present a model of a ‘gas of circles’: regions in the image domain composed of a unknown number of circles of approximately the same radius. The model has applications to medical, biological, nanotechnological, and remote sensing imaging. The model is constructed using higher-order active contours (HOACs) in order to include non-trivial prior knowledge about region shape without constraining topology. The main theoretical contribution is an analysis of the local minima of the HOAC energy that allows us to guarantee stable circles, fix one of the model parameters, and constrain the rest. We apply the model to tree crown extraction from aerial images of plantations. Numerical experiments both confirm the theoretical analysis and show the empirical importance of the prior shape information. The 'Gas of circles' model and its application to tree crown extraction. P. Horvath. Thèse de Doctorat, Universite de Szeged, Universite de Nice Sophia Antipolis, décembre 2007. Mots-clés : a priori géométrique, Contours actifs d'ordre supérieur, Champ de Phase, Gaz de cercles. @PHDTHESIS{horvath_these, author = {Horvath, P.}, title = {The 'Gas of circles' model and its application to tree crown extraction}, year = {2007}, month = {décembre}, school = {Universite de Szeged, Universite de Nice Sophia Antipolis}, pdf = {ftp://ftp-sop.inria.fr/ariana/Articles/2007_horvath_these.pdf}, keyword = {a priori géométrique, Contours actifs d'ordre supérieur, Champ de Phase, Gaz de cercles} } A `Gas of Circles' Phase Field Model and its Application to Tree Crown Extraction. P. Horvath et I. H. Jermyn. Dans Proc. European Signal Processing Conference (EUSIPCO), Poznan, Poland, septembre 2007. Mots-clés : Champ de Phase, Extraction de Houppiers. @INPROCEEDINGS{Horvath07d, author = {Horvath, P. and Jermyn, I. H.}, title = {A `Gas of Circles' Phase Field Model and its Application to Tree Crown Extraction}, year = {2007}, month = {septembre}, booktitle = {Proc. European Signal Processing Conference (EUSIPCO)}, address = {Poznan, Poland}, pdf = {ftp://ftp-sop.inria.fr/ariana/Articles/2007_Horvath07d.pdf}, keyword = {Champ de Phase, Extraction de Houppiers} } Abstract : The problem of extracting the region in the image domain corresponding to an a priori unknown number of circular objects occurs in several domains. We propose a new model of a `gas of circles', the ensemble of regions in the image domain composed of circles of a given radius. The model uses the phase field reformulation of higher-order active contours (HOACs). Phase fields possess several advantages over contour and level set approaches to region modelling, in particular for HOAC models. The reformulation allows us to benefit from these advantages without losing the strengths of the HOAC framework. Combined with a suitable likelihood energy, and applied to the tree crown extraction problem, the new model shows markedly improved performance, both in quality of results and in computation time, which is two orders of magnitude less than the HOAC level set implementation.

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