Peter DORNINGER / Dominik KRAWCZYK / Clemens NOTHEGGER
(4D-IT GmbH, Pfaffstätten, Austria – von-oben e.U., Vienna, Austria)
Keywords: Laserscanning, 3D modeling, visualization, accuracy
Supported by the ongoing development of structure from motion based 3D modeling approaches, UAVs equipped with camera systems emerged as effective platforms for 3D data acquisition of cultural heritage objects. UAVs enable close range top shots of tall objects or objects at elevated positions which were so far not accessible in a comparable manner, thus bridging the gap between high-resolution terrestrial applications and low-resolution airborne approaches based on airplanes or helicopters. While image based object reconstruction implicitly provides texture information for 3D visualization and interpretation, laserscanning in general excels with respect to the achievable accuracy and richness in detail. This applies in particular to highly structured objects, if little texture information is available or under insufficient lighting conditions. So far, however, high-resolution laserscanning was restricted to either be applied from terrestrial scanning positions or from manned aircrafts with a minimum distance of some hundred meters above the object of interest. Scan-Copter enables for the first time the UAV based application of a conventional terrestrial phase-shift laserscanner, i.e. the FARO Focus series. By means of highly accurate positioning systems and optionally supported by ground based tracking, the achievable accuracy and resolution of the thus acquired objects are close to 1 cm. For large scale applications with some hundred meters of extension, about 5 cm accuracy are achievable. In addition, the system can also be used with Riegl’s UAV-scanner VUX-1. Based on its wave-form-analysis measurement principle, this system allows penetrating vegetation as known from Riegl’s airborne LiDAR systems, but with a locally higher resolution and accuracy. By integrating conventional terrestrial laserscans with point-clouds acquired by the Scan-Copter, a homogeneous representation of objects is enabled while minimizing the occurrence of occluded areas. Thus, subsequent processing and interpretation of such data-set is significantly improved.