= Solution
For regional coverage, use \b[<stereo photogrammetry> from overlapping satellite or airborne imagery], or a radar-derived <digital elevation model> where suitable data exist. Match the same terrain features in images taken from different known viewing positions, infer their three-dimensional positions by triangulation, and georeference and grid the result. Satellite stereo or interferometric radar can cover $10^4\,\mathrm{km^2}$ efficiently; choose pixel size and vertical precision fine enough for the <fault scarps> of interest, rather than assuming every regional model resolves small scarps.
<InSAR> topographic mapping uses the phase difference from a known viewing baseline; repeat-pass deformation work must separate that height contribution from actual motion. Vegetation, cloud, radar shadow and steep slopes can leave gaps or represent the canopy rather than bare ground.<Interferometry by NASA>[Topographic mapping with separated viewing positions and the known baseline; DEM construction]{ref} Ground control and independent elevation checks are needed before interpreting small relief as active <faulting>.
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