Advances in the cooperation of shape from shading and stereo vision

Abstract

In the domain of 3D scene reconstruction this work presents the cooperation of shape from shading and stereo vision and demonstrates how to overcome a certain number of previously encountered problems. The problems of application assumptions, regularization terms and simplifications of physical models, used to overcome the problem of the modules of being ill-posed, are solved by the concept of integrating complementary knowledge of the physical world into one system. The problems due to the use of non-optimal resolution methods and too long parameter lists when the modules are integrated in a homogeneous system, are solved by the introduction of a cooperation concept for heterogeneous systems. The problem of error propagation from stereo vision to shape from shading, when only the initial and border conditions are used for the cooperation, is solved by the introduction of simultaneous constraints from both modules on all image points. The shape from shading problems of using too simple physical models for real scenes and inconsistent physical models with stereo vision are overcome by the introduction of more complex physical models. Perspective projection, point light sources and Phong's reflection model. The stereo vision problem caused by the lack of a global quality constraint when correlation is used as resolution method, is solved by using simulated annealing. The stereo vision problem arising from the use of the gray-levels for the resemblance constraint and so assuming lambertian surfaces, is solved by using the photometric characteristics from shape from shading instead.