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Homography from a Vanishing Point in Urban Scenes: iros03_article700 kb  iros03_bibtex
IEEE RSJ/International conference on Intelligent Robot and System (IROS'03),
Abstract:
In this paper, we address the problem of  computing the ego-motion of a vehicle in an urban environment using dynamic vision. We assume a planar piecewise world where the planes are mainly distributed along three principal directions corresponding to the axes of a reference frame linked to the ground plane with a vertical z-axis. We aim to estimate both the motion of the car and the principal planes in the scene corresponding to the road and the frontages of the building from a sequence of images provided by an on-board uncalibrated camera. In this paper, we present preliminary results concerning the robust segmentation of the road using projective properties of the scene. We develop a two-stage algorithm in order to increase robustness. The first stage detects the borders of the road using a contour-based approach and primarily allows us to estimate the Dominant Vanishing Point (DVP). The DVP and the borders of the road are then used to constrain the region where the points of interest, corresponding to the road lane markers, can be extracted. The second stage uses a robust technique based on projective invariant to match the lines and points between two consecutive images in the sequence. Finally, we compute the homography relating the points and lines lying on the road into the two images.


Détection robuste du plan de la route en milieu urbain: rfia04_article 3,4 Mb  
14ème Congrès Francophone de Reconnaissance de Formes et Intelligence Artificielle (RFIA'04),
Résumé :
Cet article décrit un algorithme de segmentation du plan de la route dans des images de scènes urbaines. Nous supposons que l'environnement contient une majorité de contours alignés selon les 3 directions principales. L'algorithme se décompose en deux étapes. La première détecte conjointement les lignes de fuite qui convergent vers le point de fuite dominant. Les lignes de fuite sont issues d'une détection de contours à laquelle nous appliquons des contraintes spécifiques aux scènes urbaines. Nous recherchons alors des points d'intérêts dans la région de l'image délimitée par les lignes de fuite coplanaires. Lors de la deuxième étape, nous mettons en correspondance l'ensemble des caractéristiques détectées (points d'intérêts et lignes de fuite) en utilisant les propriétés d'invariance projective entre deux prises de vues d'une même scène de façon à  estimer l'homographie induite par le plan de la route.

Trajectography of an Uncalibrated Stereo Rig in Urban Environments: iros03_article404 kb  iros04_bibtex
IEEE RSJ/International conference on Intelligent Robot and System (IROS'04),

Abstract:
This paper describes an original method to compute the relative motion of an uncalibrated stereo rig in urban environments from features lying on the road. The extraction of significant reliable features on the road remains the critical step of this method. We nevertheless detect them according to the stereo constraints and an a priori knowledge on the scene. The motion between two frames of the stereo rig is considered as rigid: the homography computation is enforced by the redundancy of the feature locations in multiple views. The method has been tested on video sequences recorded from a test vehicle that was driven in an urban environments. Promising results from these experiments will be presented.

Localisation robuste d'un véhicule en milieu urbain à partir d'un système de stéréo-vision : iros03_article20.7 Mb iros04_bibtex          Ph.D.  thesis prepared in  Icare project-team, INRIA Sophia-Antipolis