A new method of estimating shape from shading by using a constraint at zero-crossings of image brightness

An iterative method is proposed for estimating shape from shading using a constraint of surface orientation at the zero-crossings of the image brightness. This method can be applied to objects with concave surfaces and one can obtain several different 3D shapes from the same shading information. The Del /sup 2/G filter (a Gaussian operator) is used to detect the zero-crossings of the image brightness, which given information about curvature change of the surface.<
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