Returns a MULTIPOLYGON (or a MULTILINESTRING) that represent a Delaunay triangulation constructed from a collection of POINTs.
If flag=0(default value) the output is a collection of POLYGON.
If flag=1, a MULTILINESTRING is returned.
The last argument can be set to improve the quality of the triangulation. The value must be comprised between 0 and 1. If quality > 0.6, we assume that the triangle’s quality is acceptable.
Input geometry (geom) can be a POINT, a LINESTRING or a POLYGON. Nevertheless, for good practice reasons, the user may use this function only with POINTs. To process LINESTRINGs and POLYGONs it’s preferable to use ST_ConstrainedDelaunay.
Note that the triangulation doesn’t compute the intersections between lines; it takes only existing coordinates.