MultiPolygon Functions

These functions return properties of MultiPolygon values.

• Area(mpoly)

  Returns as a double-precision number the area of the MultiPolygon value mpoly, as measured in its spatial reference system.

  mysql> SET @mpoly =
   -> 'MultiPolygon(((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1)))';
  mysql> SELECT Area(GeomFromText(@mpoly));
  +----------------------------+
  | Area(GeomFromText(@mpoly)) |
  +----------------------------+
  | 8 |
  +----------------------------+
  

The OpenGIS specification also defines the following functions, which MariaDB does not implement:

• Centroid(mpoly)

  Returns the mathematical centroid for the MultiPolygon value mpoly as a Point. The result is not guaranteed to be on the MultiPolygon.

• PointOnSurface(mpoly)

  Returns a Point value that is guaranteed to be on the MultiPolygon value mpoly.

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