Stereo Matching Techniques for Cloud-Top Height Retrieval

摘要

This paper presents an ongoing study for the estimation of the cloud-top height by using only geometrical methods. It is based on the hypothesis that an infra-red camera is on board a satellite and pairs of images concern nearly the same scene. Stereo-vision techniques are therefore explored in order to test the methodology for height retrieval and in particular results of several techniques of stereo matching are evaluated. This study includes area-based matching algorithms by implementing the basic versions, without considering any further steps of optimisation to improve the results. Dense depth maps are the final outputs whose reliability is verified by computing error statistics with respect to a set of Digital Terrain Elevation Data, used as ground truth for a set of nearly cloud free images. A set of real pairs of images from the Along-Track Scanning Radiometer2 11 μm data set, has been considered. The evaluated errors range between .75 and .80 km, that is not a particularly bad result if it is compared to the resolution of the ATSR2 pixel (1 km resolution).