Application of SfM methods for the photogrammetric processing of historical aerial VHS videos

Abstract. Archival images or videos collected for various purposes may be a valuable data source for photogrammetric processing. Many such examples are reported in the literature. However, the examples of the VHS aerial video photogrammetric processing are not mentioned. This investigation aims to evaluate whether such a type of data collected in a challenging scenario, i.e., an ad-hoc helicopter flight over a flooded area, can be processed with the SfM software. The analysis is focused on image matching and bundle block adjustment. The test data consists of 6 image sequences extracted from VHS videos collected with two different cameras: RGB and near infrared (NIR) from two different heights along the Odra river near Wroclaw during the 1997 Central European Flood. In addition to the images, a low accuracy GPS trajectory logs were used to extract approximated image positions to support tie-point extraction. Archival orthophotomap and digital surface model were used to create ground control points (GCPs) and check points. Each image sequence was processed separately in Agisoft Metashape Professional software. Results showed that the matching of VHS images is possible. Although the trajectory data was of very low accuracy, it was essential to perform tie-point extraction. GCPs extracted from other geospatial data allowed for image georeferencing and creation of orthomosaics, though the geometrical accuracy of the created products is rather low. Nevertheless, executed experiments proved the usefulness of such images, especially NIR, in the flooded area mapping, in which the photogrammetric processing can be executed with the commercial SfM software.