We propose an automated approach to modeling drainage channels|and, more generally, linear features that lie on the terrain|from multiple images. It produces models of the features and of the surrounding terrain that are accurate and consistent and requires only minimal human intervention.We take advantage of geometric constraints and photommetric knowledge. First, rivers ow d o wnhill and lie at the bottom valleys whose oors tend to be either V-or U-shaped. Second, the drainage pattern appears in gray-level images as a network of linear features that can be visually detected.Many approaches have explored individual facets of this problem. Ours uni es these elements in a common framework. We accurately model terrain and features as 3 dimensional objects from several information sources that may be in error and inconsistent with one another. This approach allows us to generate models that are faithful to sensor data, internally consistent and consistent with physical constraints. We h a v e proposed generic models that have been applied to the speci c task at hand. We show that the constraints can be expressed in a computationally e ective w a y and, therefore, enforced while initializing the models and then tting them to the data. Furthermore, these techniques are general enough to work on other features that are constrained by predictable forces.