Modélisation et calcul du flot de scène stéréoscopique par une méthode variationnelle

Frédéric Huguet 1, 2
1 PRIMA - Perception, recognition and integration for observation of activity
Inria Grenoble - Rhône-Alpes, UJF - Université Joseph Fourier - Grenoble 1, INPG - Institut National Polytechnique de Grenoble , CNRS - Centre National de la Recherche Scientifique : UMR5217
2 EDP - Equations aux Dérivées Partielles
LJK - Laboratoire Jean Kuntzmann
Abstract : The scene flow is the displacement vector of any surface points estimated between two consecutive moments. Mathematically it is a three-dimensionnal vector field. This one is useful when any surface temporal deformation has to be studied, using two or more cameras. This thesis handles the scene flow computation and shows the use of this one for a geophysical project. In this aim, we worked with the geophysics sciences laboratory named Geosciencez Azur, which is located in Sophia Antipolis (Alpes Maritimes, UMR 6526 - CNRS - UNSA - UPMC- IRD). This paper presents a method for scene flow estimation from a calibrated stereo image sequence. The scene flow contains the 3-D displacement field of scene points, so that the 2-D optical flow can be seen as a projection of the scene flow onto the images. We propose to recover the scene flow by coupling the optical flow estimation in both cameras with dense stereo matching between the images, thus reducing the number of unknowns per image point. Moreover our approach handles occlusions both for the optical flow and the stereo. We obtain a partial differential equations system coupling both the optical flow and the stereo, which is numerically solved using an original multi-resolution algorithm. Whereas previous variational methods were estimating the 3-D reconstruction at time $t$ and the scene flow separately, our method jointly estimates both. We present numerical results on synthetic data with ground truth information, and we also compare the accuracy of the scene flow projected in one camera with a state-of-the-art single-camera optical flow computation method. Results are also presented on a real stereo sequence with large motion and stereo discontinuities. We finally present the original approach developed in Geosciences Azur to study the gravitary mountain landslides, the 3D physical modelling. We describe the experimental stereo device used to track the deformations of the reduced moutain model used by the geophysicists. 3D reconstruction and scene flow results are shown, as well as the tracking of the observed surface deformations, in the fourth chapter of the thesis.
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Frédéric Huguet. Modélisation et calcul du flot de scène stéréoscopique par une méthode variationnelle. Modélisation et simulation. Université Joseph-Fourier - Grenoble I, 2009. Français. ⟨tel-00421958⟩

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