Pierre Gurdjos

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We investigate the projective properties of the feature consisting of two concentric circles. We demonstrate there exist geometric and algebraic constraints on its projection. We show how these constraints greatly simplify the recoveries of the affine and Euclidean structures of a 3D plane. As an application, we assess the performances of two camera(More)
We propose a combined line segment and elliptical arc detector, which formally guarantees the control of the number of false positives and requires no parameter tuning. The accuracy of the detected elliptical features is improved by using a novel non-iterative ellipse fitting technique, which merges the algebraic distance with the gradient orientation. The(More)
The plane-based calibration consists in recovering the internal parameters of the camera from the views of a planar pattern with a known geometric structure. The existing direct algorithms use a problem formulation based on the properties of basis vectors. They minimize algebraic distances and may require a ‘good’ choice of system normalization. Our(More)
This paper deals with the problem of calibrating a (moving) camera with varying focal length, from n views of a planar pattern with a known Euclidean structure. The main issue under discussion is to find a new method whose complexity does not dramatically increase with the number n of views, contrary to existing methods. Our contribution is to relate this(More)
Our problem is that of recovering, in one view, the 2D Euclidean structure, induced by the projections of N parallel circles. This structure is a prerequisite for camera calibration and pose computation. Until now, no general method has been described for N > 2. The main contribution of this work is to state the problem in terms of a system of linear(More)
We present a new formulation to the well known problem of shape-from-texture from a single image by casting the task as a multi-plane based camera pose estimation problem. Our first contribution is methodological: we show that by using a piecewise affine model, instead of a perspective one, we can avoid the numerical instabilities in the estimation of the(More)
Plane-based calibration is now a very popular procedure because of its flexibility. One key step consists in detecting a set of coplanar features, from which the Euclidean structure of the corresponding 3D plane has to be computed. We suggest to use confocal conics as calibration targets, as they offer undeniable advantages over other ones (e.g., points or(More)