Segmentation of laser altimeter data for building reconstruction: Different procedures and comparison

One important step in the reconstruction of buildings from laser altimeter data is the segmentation step. In this contribution four procedures known from literature are investigated and compared. One procedure, which was made for detecting straight lines, which produces a segmentation as an intermediate result, was used. Three other procedures were installed, which are based on region growing. For each of the procedures experiments with an extensive variation of the parameters were carried out. For the particular task of roof reconstruction and the speciality of height data an own procedure was developed. In this procedure the distance measure is not computed from derived properties but directly from the sets of points. Moreover it also uses the knowledge about the separation of background and foreground and it is regulated by only one parameter. In order to make the segmentation results comparable known comparison measures for single segments (the relative correspondence related to the model and the result) were taken. For the estimation of the whole segmentation several aspects of the evaluation of single segments are discussed and a complete evaluation function is developed. For a quantitative measurement some buildings were chosen as examples.