Calibration and 3D Measurement from Martian Terrain Images

In this paper a new on-Mars calibration procedure of a planetary lander vision system is presented. It is based on recent developments in computer vision. The calibration is retrieved from the images of the Mars terrain (the same images from which the 3D measurements of the terrain are obtained). The procedure is based on the relations between multiple views of the same scene. The main advantage of this calibration procedure is that it allows to retrieve the calibration on mars without any additional requirements on the system. Once the system has been calibrated, the same images can be used to estimate a digital elevation map of the environment around the lander. This means that the terrain based calibration causes no overhead on transmission. These images are first processed pairwise using a stereo algorithm yielding sub-pixel disparity maps. In order to perform the path planning a digital elevation map is required. A new algorithm was developed to efficiently extract this from the disparity maps. This algorithm can generate a regular digital elevation map at any desired resolution (interpolating if necessary) and easily takes occlusions into account.