Shape-from-Shading Algorithm for Oblique Light Source
Shape-from-shading method for oblique light source appears most applicable with minimal effects of the convex-concave ambiguity and shadows. In this paper, first, a robust iterative relation that reconstructs shape is constructed by applying the Jacobi iterative method to the equation between the reflectance map and image for each of the four approximations of the surface normal and by combining the resulting four relations as constraints. The relation ensures convergence, but that alone is not enough to reconstruct correct shapes for bright image parts or mathematically singular points. Next, to solve the problem, the light direction is tilted in slant angle following a criterion and the average tilt of the resulting shape is compensated. A numerical study using synthetic Mozart images shows that the method works well for a wide direction of the light source and that it gives more correct shapes than any of existing methods. Results for real images are also given, showing its usefulness more convincingly.
KeywordsReal Image Deformable Model Good Shape Light Direction Object Region
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