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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)
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)
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)
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.(More)
Les hypothèses simplificatrices usuelles du shape from shading , technique bien connue de reconstruction tridimen-sionnelle à partir d'une seule vue, amènent à le formuler sous une forme apparemment simple, qui est ((l'équation de l'eikonale)). La résolution de cette équation pose néan-moins de sérieuses difficultés, qui sont dues en grande par-tie à(More)
High-resolution panoramic video with a wide field-of-view is popular in many contexts. However, in many examples, like surveillance and sports, it is often desirable to zoom and pan into the generated video. A challenge in this respect is real-time support, but in this demo, we present an end-to-end real-time panorama system with interactive zoom and(More)
Document digitization is faster and more affordable using digital cameras than scanners. On the other hand, if we aim at extending the basic digital camera functionalities for such a purpose, post-processings will be of first importance, at least to improve the text legibility. In this paper, we address the specific problem of the virtual flattening of(More)