Laser Dtm Generation for South-tyrol and 3d-visualization

In the past years laser scanner data has established itself as an accurate and reliable data basis for many applications. Highly accurate digital terrain models (DTM) can be derived by filtering laser data that contains information on the terrain and objects covering the surface. Also in wooded areas the DTM’s have a high accuracy, since many of the laser pulses penetrate the vegetation and provide information about the terrain. Such DTM’s can be used for hydrologic modelling, the planning of larger building projects, the modelling of avalanches or the exact ortho-rectification of optical remote sensing data. The remaining laser data points that describe the objects covering the terrain, mostly buildings and vegetation, can be used for building reconstruction or the derivation of forest parameters. In combination with a DTM this information can be used for noise modelling, city models, forest inventories and 3D visualisations. In terms of such a wide range of applications the autonomous province Bolzano/Italy decided 2003 to capture the entire area of the province, 7500 km2, with laser scanner data for the extraction of a DTM. To ensure a high quality of the laser DTM Joanneum Research/Institute of Digital Image Processing, responsible for the definition of the laser data capture parameters and the data processing, had to find cost effective laser data capture parameters as well as efficient methods for the verification of the delivered data, the handling of strip mismatches, GPS height offsets, atmospheric influences and the filtering of the laser data. This paper is meant to give an overview on the running project ‘Laser DTM province Bolzano’, describing the selected parameters for the data capture, which helped to save costs, the data verification and processing. Concerning the misalignment of neighbouring stripes a new approach, BIAS (best incidence angle to surface), was developed, which improves the DTM quality and runs fully automatic. Together with a new filtering approach, hierarchic region growing, a processing chain was implemented which enables the generation of accurate DTM’s in a most efficient way. In addition the possibilities of 3D landscape visualization based on laser scanner data will be discussed.