科研之友
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摘要
With the development of terrestrial laser scanning (TLS) and its applications in forestry, the question arises as to how the scanners should be ideally placed for the best possible data acquisition. We searched for an optimal scanning distance for recognition of stems in natural beech-dominated forests, focusing particularly on the shading effect of tree stems and terrain. Recognised tree stems in TLS point clouds were compared with reference stem maps. A GIS-based visibility simulation was carried out to enhance the quantitative assessment and generalizability of results. The analyses also include the additive effect of multiple scanning positions. Single scans only have a tree recognition rate above 80% up to a distance of 15 m from the scanner; using at least three scanning positions a comparable recognition rate was attained up to 20-25 m. A simulated coverage of a beech-dominated natural forest by laser beams using a 40 m square grid of scanning positions captured at least half of the stem perimeter for more than 90% of trees with a DBH >= 10 cm. In sites with rough terrain, the relief configuration has a more significant effect of occlusion than present tree stems.
- 出版日期2013-4
