We will use the SRTM raster, loaded as 100 x 100 tiles, in this chapter's first recipe. With it, we will generate slope and hillshade rasters using San Francisco as our area of interest.
The next two queries in the How to do it section use variants of ST_Slope() and ST_HillShade() that are only available in PostGIS 2.1 or higher versions. The new variants permit the specification of a custom extent to constrain the processing area of the input raster.