Integration of a Terrestrial Lidar on a Mobile Mapping Platform: First Experiences

Mobile mapping techniques represent an efficient way to supply the requirements imposed by the development of 3D GIS, urban digital models and their applications using virtual and augmented reality. The methods widely applied in this domain depend on the video and photogrammetric sensors which provide accurate results but with long time of post-processing. Hence, the integration of a terrestrial laser scanner or terrestrial LiDAR in such mobile mapping platforms would allow obtaining point cloud quickly at low operating cost. However this technique requires an ideal synchronisation between the different components. Each laser pulse has to be strictly synchronized with the GPS/INS module which enables to establish the trajectory of the platform. Terrestrial Laser Scanners (TLS), though, mostly designed for static stations, usually do not give the exact time of each laser pulse. In this paper, we show that under some conditions, it is possible to synchronize point cloud obtained by the TLS with the trajectometry data, in order to achieve the georeferencing of the scanned cloud points into a world coordinate system. We describe the error model and accuracy that one can reach with such a platform, and we illustrate the theoretical results with experimental data obtained by a platform prototype developed at the MAP-PAGE laboratory at INSA of Strasbourg. Thus, we demonstrate that a terrestrial vehicle-borne LiDAR technique can be considered as a novel alternative for the traditional mapping methods.