Algorithms for shape from shading and occluding boundaries

The problem of shape from shading and occluding boundaries can be reduced to solving a system of nonlinear equations for a smoothing spline, using regularization. The author discusses some theoretical issues corrected with this problem. He studies the existence and uniqueness of the smoothing spline. For solving the system of equations, he presents an iterative algorithm and proves that it converges to the unique solution for arbitrary regions. He also discusses efficient implementations of the iterative method, and analyzes their computational complexity