Functions that show information about boundaries, envelopes, and rings
You can use certain functions to return information about demarcations that divide an inner part of a geometry from an outer part, or that divide the geometry itself from the space external to it.
For example, ST_Boundary returns a geometry's boundary in the form of a curve.
The following functions show information
about boundaries, envelopes, and rings:
- ST_Boundary
- ST_Envelope
- ST_ExteriorRing
- ST_InteriorRingN
- ST_NumInteriorRing
- ST_Perimeter