Multi-view visible images (satellite, aerial, UAV,…) together with precise information about sensor position, viewing conditions and camera specifications.
Detailed georeferenced data of the altitude of the surface (including terrain and off-terrain objects).
A detailed Digital Elevation Model can be used not only to look for special relief features but also for further processing (e.g. orthorectification) or a variety of different analysis (e.g. visibility, trafficability, detection of trenches, etc.).