Abstract : We present in this article a system which improves a DEM. The method reconstructs all the facades of the build- ing and then, corrects the initial DEM by deleting the points of the roofs which pass over the boundaries defined by the facades. We correct the shapes of the buildings with the initial photographs to have sharp contours. The proposed approach does not use any a priori information about the orientation of the facades and the shape of the buildings. We present results with synthetic and real images.