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1.
Reconstructing 3D curves with euclidean minimal spanning trees
Simon Kolmanič, Nikola Guid, 2006, original scientific article

Abstract: In this paper, we present a new efficient algorithm for reconstruction of nonintersecting 3D curves from a sufficiently den se sample. We use the Euclidean minimal spanning trees to identify line segments reconstructing curve shapes. To deal with more than one curve in a sample and to eliminate noisy data, we introduce chains of connected line segments. With the incremental growth based on heuristics, the chains contain finally curve shapes. The method is robust and fast for both 2D and 3D curves.
Keywords: oblaki točk, rekonstrukcija krivulj, evklidska minimalna vpeta drevesa, point cloud, curve reconstruction, euclidean minimal spanning trees
Published: 10.07.2015; Views: 675; Downloads: 14
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2.
Simulating various terrestrial and UAV LiDAR scanning configurations for understory forest structure modelling
Marina Hämmerle, Niko Lukač, K.-C. Chen, Zsófia Koma, C.-K. Wang, K. Anders, B. Höfle, 2017, published scientific conference contribution

Abstract: Information about the 3D structure of understory vegetation is of high relevance in forestry research and management (e.g., for complete biomass estimations). However, it has been hardly investigated systematically with state-of-the-art methods such as static terrestrial laser scanning (TLS) or laser scanning from unmanned aerial vehicle platforms (ULS). A prominent challenge for scanning forests is posed by occlusion, calling for proper TLS scan position or ULS flight line configurations in order to achieve an accurate representation of understory vegetation. The aim of our study is to examine the effect of TLS or ULS scanning strategies on (1) the height of individual understory trees and (2) understory canopy height raster models. We simulate full-waveform TLS and ULS point clouds of a virtual forest plot captured from various combinations of max. 12 TLS scan positions or 3 ULS flight lines. The accuracy of the respective datasets is evaluated with reference values given by the virtually scanned 3D triangle mesh tree models. TLS tree height underestimations range up to 1.84 m (15.30 % of tree height) for single TLS scan positions, but combining three scan positions reduces the underestimation to maximum 0.31 m (2.41 %). Combining ULS flight lines also results in improved tree height representation, with a maximum underestimation of 0.24 m (2.15 %). The presented simulation approach offers a complementary source of information for efficient planning of field campaigns aiming at understory vegetation modelling.
Keywords: forest structure, understory, laser scanning simulation, full waveform, 3D point cloud analysis, field campaign planning
Published: 09.10.2017; Views: 592; Downloads: 212
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