For readers who want to apply the theories described in this chapter to real engineering problems and numerically evaluate the solution, the authors provide two computing projects: one is a simulation experiment, and the other is real data analysis. Geodetic scientists all over the world monitor the land movement using GPS data. Each post receives GPS signals from multiple satellites over a long time, say, hours. By statistical procedures, its position relative to the earth is computed very precisely up to millimeters. Stereo vision is a method for reconstructing the 3D structure of a scene from corresponding points by triangulation; if the configuration of the cameras and their intrinsic parameters are known, one can compute the “ray” or the “line of sight” of each pixel, and the intersection of the corresponding rays gives their 3D position.