This paper describes a multiresolution approach combining stereo intensity data with data produced from a triangulation laser range finder. Stereo data can be acquired rapidly at high-resolution, but the complexity of the correspondence problem has lead researchers to turn to other depth derivation methods. A recent trend has been to use laser range finders which provide direct depth information. Due to limitations of the technology and cost, most available laser range finders produce relatively noisy and sometimes missing depth information at a comparatively lower speed. This research explores the idea of a multiresolution approach for the acquisition of a complete, relatively noise-free, and high-resolution depth map from a low-resolution triangulation range image and a stereo pair of high-resolution intensity images.
Stereo intensity data are collected using an additional camera orthogonal to the laser range finding configuration, thus providing depth information for surfaces invisible to the laser finding system. It also provides smoother depth values at edges, where many laser reflectance problems occur, and finer detail, since intensity data is capable of highlighting more detailed features of an object. Depth information from the laser range data is used at edges common to one of the stereo intensity images, thus reducing the edge correspondence problem by constraining the search for edges in stereo matching. These common edges, and the inter and intra-level linking of edges in the pyramid, allow a process where the coarse laser depth information drives a multiresolution stereo matching process to construct a high-resolution depth map.