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Many algorithms have been suggested for the shape-from-shading problem, and some years have passed since the publication of the survey paper by Zhang et al. [1]. In this new survey paper, we try to update their presentation including some recent methods which seem to be particularly representative of three classes of methods: methods based on partial(More)
The Shape-from-Shading problem is a classical problem in image processing. Despite the huge amount of articles that deal with it, few real applications have been developed because the usual assumptions considered in the theory are too restrictive. Only recently two new PDE models have been proposed in order to include in the model the perspective(More)
Rapport de recherche IRIT N • 2004–2–R janvier 2004 Résumé Plusieurs algorithmes ontété proposés pour résoudre leprobì eme du shape from shading, et la publication du livre de Horn et Brooks [27] commencè a dater. Dans ce rapport, nous faisons un tour d'horizon le plusà jour possible, en détaillant plusieurs algorithmes qui nous semblentparticulì erement(More)
A numerical scheme to solve the Dirichlet type problem for the first order Hamilton-Jacobi equation related to the shape-from-shading model is proposed. The algorithm computes the maximal solution of the problem provided a compatibility condition on the dis-cretization steps is satisfied. This global formulation a~ows to include in the model the(More)
In this paper we study a perspective model for shape from shading and its numerical approximation. We show that an ambiguity still persists, although the model with light attenuation factor has previously been shown to be well-posed under appropriate assumptions. Analytical results revealing the ambiguity are complemented by various numerical tests.(More)