Abstract: This paper proposes an algorithm of combining multiple needle maps for recovering 3-D surface depth. The algorithm can produce first a pair of the needle maps by the dual photometric stereo system and solve disparities between the corresponding areas in the two needle maps,then it combines the disparities correctly and matches them accurately, and finally it reconstructs the 3-D depth of the object surface. This method is very useful for us to conduct research on 3-D surface depth reconstruction and to recover scene structures.

Key words: dual photometric stereo system, multiple needle maps for stereo images, absolute depth, global coordinate system