The second part evaluates 21 studies on this topic, their aims, and how they dealt with error sources and the necessity of validation. These are outlined in the first part of this article with a focus on potential error sources and the impact of the most important constraints, namely, temporal and perpendicular baselines. Nonetheless, the technical conditions are provided for successful applications involving DEM generation. This is mainly because of the narrow orbital tube, which was primarily designed for subsidence measurements using differential interferometry. However, while interferometric approaches to detect surface deformations are continuously being published, only a few studies address the derivation of digital elevation models (DEMs) from Sentinel-1 data. With the launch of Sentinel-1 in 2014, a new era of openly accessible spaceborne radar imagery was begun, and its potential has been demonstrated throughout all fields of applications.
