1. A method for three-dimensional motion mapping in video encoding, comprising: a) performing a reverse three-dimensional transform for a set of anchor pixels in a current frame of video, thereby producing a set of transformed anchor pixels; b) for each reverse transformed pixel, indicating that the reverse transformed pixel is occluded if the estimated depth for a corresponding pixel in the previous frame is greater than a real depth for the corresponding pixel in the previous frame, or indicating that the corresponding pixel in the current frame is visible, or indicating that the reverse transformed pixel is not occluded if the estimated depth for the corresponding pixel in the previous frame is not greater than a real depth for the corresponding pixel in the previous frame. c) constructing a motion vector map for at least a subset of the set of reverse transformed pixels; d) deriving a best target motion vector for each section in a first set of sections in the current frame using the motion vector map or performing motion estimation for each section in a second set of sections in the current frame using the motion vector map, wherein the sections in the second set include occluded pixels; e) deriving target motion vectors for one or more groups of two or more sections of the current frame, each group comprising two or more adjoining sections each with best target motion vectors; and f) encoding the current frame using the target motion vectors, the best target motion vector for each section, or motion estimation results.