The Use Case:

Access arbitrary regions - not just boxes - in a datacube, with regions given by vector polygons.

The service: Polygon ring cutout

This not (yet?) standardized extension to OGC WCS and WCPS allows clipping against polygon provided in WKT (Well-Known Text) representation. Polygons can self-intersect, and multi-polygons are possible (such as for areas with many lakes). The clip() function operates along space and time, it can alternatively discard the exterior or the interior. The result of this WCPS query is a 2-D image considering only the polygon interior, overlaid on a base map.

The service: trajectory extraction

Line string clipping is the next example. We use a trajectory walking over the Germany DEM, given again by the SRTM 1 arc-second DEM, while extracting all values encountered. The result of this WCPS query is a 1-D value series.