Denoising Point Cloud Data of Small-structured Free Form- Surfaces Captured by a Phase-based Laserscanner

Terrestrial laser scanners based on the time-of-flight measurement principle or the phase comparison method are used for cultural heritage documentation. Only if the scanned surfaces consist of extended, only slightly curved structures, the noise of the point cloud becomes nearly irrelevant as soon as the point cloud is replaced by a parametric or analytic description of the surface. In this paper, the usage of a phase based scanner for capturing small-structured free form surfaces shall be investigated, whereas two procedures are used to reduce the noise of the point cloud: repeated scanning and calculation of average, then smoothing the point cloud with an edge-preserving filter, based on anisotropic diffusion. The physical background of the anisotropic diffusion filter is given, the work-flow is described and the gained results are discussed. It will be seen, that via repeated scanning and usage of an edge-preserving filter good results also in close-range can be achieved with a terrestrial laser scanner based on the phase comparison method.