Comparison of 3D Accuracy of Terrestrial Laser Scanning and Digital Photogrammetry: An Archaeological Case Study

摘要

Terrestrial laser scanning is already successfully being used in a broad variety of applications where a very dense and highly accurate recording of an object is needed. Also in the field of cultural heritage and archaeology, laser scanning is more and more being used for 3D geometric information and conservation of historic buildings or excavation sites. This paper deals with the high resolution terrestrial laser scanning and photogrammetric restitution of the historic site of the Sint-Baafs Abbey (Gent, Belgium) to obtain a geometrically accurate 3D model. Previous research indicated that for high accuracy applications, a sufficiently fine lateral resolution is necessary. The laser scan recording of the site in a previous project did not meet this required lateral resolution to firmly compare both terrestrial laser scanning and digital photogrammetric restitution. Therefore, the complete setup has been repeated and improved. The inside and outside walls of the Abbey which were of interest for this project have been scanned with the phase-based Leica HDS6100 laser scanner. The recording of the digital stereo couples and the topographical measurements for the photogrammetric restitution have been done simultaneously. Topographical measurements were also performed for a set of control points. The coordinates of these control points function as the 'ground truth' to which the results of the laser scanning and the photogrammetric restitution are compared. The results indicate that terrestrial laser scanning meets the feasible accuracy with digital photogrammetry. If a suited type of laser scanner and optimal resolution settings are applied, terrestrial laser scanning enables the high accuracy recording of cultural heritage and archaeological sites.