| dc.description.abstract | Geometrically and topologically correct 3D building models are required to satisfy the increasing demand in, for instance virtual reality, emergency response, robot navigation, and urban planning. Airborne Laser Scanning (ALS) is still the preferred data acquisition system for automated building modelling. In this study, a novel approach for the generation of 3D roof boundaries in Airborne Laser scanner data is presented. The workflow is commenced by segmenting the point cloud which is followed by a classification step and a rule based roof extraction step. Boundary points of the connected roof planes are extracted and fitted straight line segments. We introduce the usage of graph cycles for maintaining the correct topology and optimising the roof reconstruction. Ridge-lines and step-edges are mainly extracted to recognise correct topological relationships among the roof faces. Inner roof corners are geometrically fitted based on the closed cycles. Outer boundary is reconstructed using the same concept but with the outer most cycle. In here, union of the sub cycles is taken. Intermediate line segments are intersected to reconstruct the roof eave lines. Performance analysis of the test results is provided to demonstrate the applicability of the method. The method is further evaluated with the ISPRS benchmark test data and results prove the applicability and robustness of the approach. | en_US |
