Abstract. This paper presents a feasibility study on the extraction of railway parameters from high-precision UAV photogrammetry. A two-stage methodology is adopted: first, point-cloud accuracy and rail-surface coverage are optimized through controlled laboratory and field acquisitions; second, the resulting point clouds are evaluated against the local precision requirements for railway parameter extraction. Laboratory tests show that the SfM workflow is intrinsically capable of sub-millimeter agreement under controlled conditions. In the field, standard nadir and higher-altitude flights proved insufficient to reconstruct the narrow rail-side geometry required for accurate gauge estimation. The best results were obtained by combining a 15 m nadir flight with additional side-looking images at 2.5 m and 5 m, yielding local fitted-surface RMS values down to 0.25 mm and about 0.37 mm on the rail running surface. Although the best lightweight UAV configuration still showed a 2.2 mm gauge discrepancy relative to TLS, the laboratory validation and the strong performance of optimized acquisitions indicate that tolerance-compliant railway parameter extraction may be achievable with higher-end UAV platforms and improved rail-side visibility. Overall, the results confirm the strong potential of UAV photogrammetry for near-industrial railway documentation.
Lucas De Burggrave, E. Bartczak, S. Cuypers et al.· The International Archives o...· 0 citations
Abstract. This paper presents a semi-automated pipeline for extracting architectural plans from terrestrial LiDAR point clouds of archaeological sites characterized by irregular geometries and significant surface degradation. The proposed workflow converts dense three-dimensional data into simplified two-dimensional representations by combining geometric alignment, expert-guided cross-section selection, feature detection using Intrinsic Shape Signatures (ISS), region-based segmentation, and polyline simplification. The method is specifically designed to handle rock-cut tomb environments, where erosion, noise, and non-planar surfaces complicate conventional Scan-to-Plan approaches. The pipeline is evaluated on six tombs from the Sheikh Said necropolis in Middle Egypt, covering a range of architectural configurations and preservation states. Results demonstrate that the method efficiently produces CAD-compatible outlines that capture the dominant structural geometry while significantly reducing manual drafting time. However, the accuracy of the generated plans depends on surface conditions, with degraded or ornamented areas introducing geometric artifacts that require expert refinement. The proposed approach provides a robust geometric baseline for archaeological documentation and highlights the potential of human-in-the-loop workflows for complex heritage environments.
Marianna Bartrick-Krana, Roberto de Lima-Hernandez, A. Vandesande et al.· The International Archives o...· 0 citations