Viewshed

terraintopography
Binary or multi-observer visibility raster derived from a DEM and one or more observer points. For a single observer the output is binary (1 = visible, 0 = not visible, nodata = outside analysis area); for multiple observers it is typically categorical, encoding how many observers see each pixel. Line-of-sight is computed by ray-tracing from observer to target across DEM cells, with optional corrections for earth curvature and atmospheric refraction. Used by line-of-sight analysis, telecommunications and radar siting, wildlife habitat sightline modelling, and scenic / recreation planning ops.
Canonical units: categorical