High Resolution Historical Topography: Getting More from Archival Aerial Photographs

High resolution elevation data is fundamental information for multiple applications in geomorphology spanning from visual analyses to modeling. Nowadays, gathering of high-quality elevation data relies on multiple sensors and technologies that can be mounted on terrestrial, aerial and satellite platforms. In the last few years, the Structure from Motion (SfM) algorithms have made the acquisition of high and very-high resolution elevation data from optical images acquired with high overlapping rates at virtually no cost possible. Such a feature made it possible to exploit remote sensing archival imagery to build historical topographic information with unprecedented detail. However, despite the increasing number of applications of SfM algorithms in the scientific literature, still little has been done in terms optimization and quality evaluation of the results. We have applied the SfM algorithm developed in the photogrammetric open source software MicMac to six black and white aerial photographs taken in 1954 at 1:33,000 in a mountainous and steep area in Central Italy. The aim of the experiment consists of a quantitative evaluation of the digital surface models obtained for different scanning settings.