Talks and Poster Presentations (without Proceedings-Entry):

L. Eysn, M. Hollaus:
"High Resolution Tree Models - Modeling of a Forest Stand Based on Terrestrial Laser Scanning and Triangulating Scanner Data";
Talk: Europen Lidar Mapping Forum (ELMF), Amsterdam, The Netherlands; 2013-11-10 - 2013-11-12.

English abstract:
Ray tracing within forested areas rely on detailed 3D Models of all objects within the investigated area. Current terrestrial laser scanners (TLS) and triangulating scanners (TS) are able to acquire such data. As trees are complex objects, the modeling is challenging and a fully automatic reconstruction of trees based on TLS data is often limited. In contrary to the tree structure the foliage can not be derived from TLS data directly because the needles are too small. In this paper a semi-automatic method for extracting tree structure based on equirectangular projections (range and intensity) of TLS data is presented. Based on these maps branches and stems are digitized in 2D, which enables simple navigation and raster processing. Afterwards the models are transformed to 3D space. The coniferous foliage is modeled by applying a cloning approach using models of different shoots. They are modeled based on high-density data acquired with a TS mounted on a measuring arm. To control the cloning process the local TLS point densities are analyzed using a voxel approach to obtain the cloning positions for the shoots. The methods are applied to a TLS dataset acquired in a managed forest in Germany. In total 34 TLS-scans were acquired to measure approx. 90 spruce trees. Shoots samples were collected and measured with the TS in the laboratory. The modeled forest scene shows a high degree of completeness and correctness and provides an excellent input for ray tracing experiments.

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