Discrepancy Analysis Between Close-Range Photogrammetry And Terrestrial LiDAR

This study presents a comparison of building measurements performed on 3D models generated by two different approaches. In one approach, the models were produced via close-range photogrammetry. Such models are based on still-frame photographs that are, post-processed with commercially available photogrammetric software. In the second approach, 3D point-cloud models were generated via laser scanning. For this purpose, three case studies were conducted. The first was a simple one story structure, the second was a multi-story Maya ruin, and the third was an earth filled terrace. Several benchmarks within a closed traverse were established to serve as standard georeference points for all accuracy comparisons. Several physical target points were then marked on the exterior walls of the structure. They are referred here as reference wall points. The reference wall points were then measured with a total-station instrument. After photographs were taken and laser scanning of the structure performed, the coordinates of the reference wall points were also determined from the respective models. The coordinates were then compared with the ones obtained with the total-station instrument. Coordinates and distances from each procedure were compared to determine relative discrepancies and accuracies. The results of this study demonstrate that the close-range photogrammetry can provide accurate enough information to be used as an alternative for total stations or laser scanners when measuring buildings or other relatively small projects