Josh: I think you are quite correct in pointing out that the algorithm you suggest would give quite good results, however the beauty of the algorithm presented is that it has an analysis-by-synthesis approach. It tests at each stage the "goodness" of the depth map and improves in an iterative manner. No doubt that it seems to be computationally very expensive but the quality of results is incredible. The algorithm you suggest would give a depth map in one shot but it would not probably correct wrongly initialized depth map.