Integration of Defocus and Focus Analysis with stereo for 3D shape recovery

Image Defocus Analysis (IDA), Image Focus Analysis (IFA) and Stereo Image Analysis (SIA), are integrated for recovering the three-dimensional (3D) shape of objects. Integrating IDA, IFA, and SIA, has important advantages because IDA and IFA are less accurate than stereo but they do not suffer from the correspondence problem associated with stereo. Therefore, a rough 3D shape is first obtained using IDA and IFA without encountering the correspondence problem. The amount of computation and accuracy at this stage is optimized by using IDA first and then the IFA. Accuracy is further improved by projecting a high contrast pattern on to the object of interest. The rough shape thus obtained is used in a stereo matching algorithm to solve the correspondence problem efficiently. The amount of computation in matching is reduced since the search for correspondence is done in a narrow image region determined by the approximate shape. Also, the knowledge of approximate shape improves the matching accuracy by minimizing false matches due to occlusion. The method for integrating IDA, IFA, and SIA is presented in detail. The method has been implemented on a vision system named SVIS. Experimental results of the method are presented.