In order to extract a drainage network from a LANDSAT scene of mountainous terrain, it is necessary to use an illumination model to separate the reflectance information from the topographic information in the LANDSAT data. From the reflectance information, visible stream segments can be detected. From the topographic information, ridges and valleys can be located and assigned relative elevations by an elevation growing model. Based on these, a complete elevation model can be estimated by interpolating between ridges and valleys and this estimate can be improved by making it consistent with the topographic information. Also the LANDSAT imagery can be reconstructed to evaluate the illumination model. In order to label flow directions of visible stream segments, constraints at junctions based on orientations and lengths are defined and a consistent labeling technique is used. / Ph. D.