A multi-scale reconstruction framework is presented, where the red triangle represents the current reference frame for all levels, blue triangle and dot represent the keyframes within optimization window, the gray triangle represents the current frame, and the dashed triangle and dot mean the keyframes outside optimization window. At first level, the current frame is tracked against the current reference frame and all keyframes in the window. It should be noted that this layer is exactly same as conventional DSO. At a higher level, the inverse depth map of the current reference frame is further refined by optimizing the depth from distant frames.
The qualitative evaluation of reconstruction of MS-DSO and DSO on Symphony Lake Dataset is illustrated with reconstructed scene model from Google Earth. Inc. The quantity of points in point cloud counts the number of well-reconstructed points, thus can be treated as a measure of reconstruction precision. Observed from these two pairs of point clouds, our proposed MS-DSO could provide a much larger amount of well-constructed points than that of DSO with same parameters.