Shape from shading(SFS) is one of the critical techniques to shape recovery in computer vision

which obtains 3-D shape of the visible surface of an object from only one image of it using the shading knowledge in the given picture. In order to give an outline of over 30 years' research work on SFS problems and try to make sense to beginners of advantages and disadvantages of varions methods to solve such problems

this paper adopted the common classification of all SFS methods presented up to now

namely

minimizaiton methods

propagation methods

localization methods

and linearization methods

to each of which some typical algorithms were analyzed both from principles and experiments point of view. Comparisons between and evaluations of these methods together with their corresponding algorithms were also given in several aspects

such as the uniqueness of the recovered surface

the approximation ability to the true surface

the effectiveness and applicability of the algorithm

etc.Through the discussion

we agreed that there is no method applicable to all kinds of SFS problems

and each method has its own range of applicability. In the end

the paper concluded in the unresolved problems to SFS as well as some indications to future work.