True orthophoto generation using multi-view aerial images
Usually aerial imagery are acquired through perspective projection which results in relief displacement in the map. Therefore, orthophotos from large scale aerial images over urban area often suffer from double mappings caused by sudden elevation changes in the scene. In the generation of true orthophotos, one aims at removing these perspective displacements and occlusions. Hence, knowledge of the surface shape is needed, as it has great impacts both on the orthorectification and occlusion identification. Mostly, the relief displacements are caused by buildings. In this paper, we present a method for the generation of true orthophotos from overlapping aerial images of known orientation, especially in built-up areas. Apart from the aerial images, the method does not depend on additional data sources. In particular, we focus on the derivation of building roof outline model using image segmentation and edge detection techniques under the guide of the classification result of point cloud from image matching . Experiment results on real data show the feasibility and the performance of the method.