Adding the Third Dimension to a Topographic Database Using Airborne Laser Scanner Data

Laser altimetry provides reliable and detailed 3D data, which to certain extent, can be processed (semi-)automatically into 3D information. The use of an additional source of information, like 2D GIS data, can improve the reconstruction process, especially in terms of time and reliability. This paper describes the reconstruction of 3D topographic objects by fusing medium scale map data with the national height model, acquired by airborne laser altimetry. We assume that the topographic objects can all be described by smooth surface patches. We therefore first process the laser data to extract the larger smooth surfaces. Discontinuities are, however, preserved. The resulting set of laser points is used to first assign heights to the lines of the 2D GIS data and later on to reconstruct the surfaces of the objects. A set of processing rules is used in the first step to obtain the most likely heights of the object outlines. A constraint Delaunay triangulation of combined 3D outline points and laser points is used for the surface reconstruction. The developed method is demonstrated with a 3D reconstruction of a complex motorway interchange.