Improvement of automatic DSM generation over urban areas using airborne laser scanner data

Airborne laser scanning has provided an efficient and accurate method of data acquisition for the determination of visible surface topography. The laser data can be quickly processed to provide coordinates of points on the visible surface with high spatial frequency and precision. This technology has benefits as compared to photogrammetric techniques, however there are limiting factors due to the laser data having no thematic information. The limitations may be overcome by utilizing aspects of both laser altimetry and photogrammetry in the surface determination process. Research has been undertaken to accurately determine the visible surface in urban areas using airborne laser scanner data and digital aerial imagery. In this project, edges detected in the aerial images are used to refine the digital surface model (DSM) produced using data from an airborne laser scanner. The three dimensional edge information allows improvement of the laser DSM by providing accurate locations of surface discontinuities. Therefore the laser data and the edge information are merged to obtain the benefits of each data set, facilitating the generation of an accurate terrain model. The approach has been tested over an urban site covering Ocean City, Maryland, USA. Laser data and aerial imagery, acquired on the same day, are available. Experiments were performed to test and refine the algorithm. This paper presents the data fusion approach, describes the data set and details the results of experimentation undertaken to investigate the validity of the approach.