Well-Known Text (WKT) Format

The Well-Known Text (WKT) representation of Geometry is designed to exchange geometry data in ASCII form. For a Backus-Naur grammar that specifies the formal production rules for writing WKT values, see the OpenGIS specification document referenced in , "Spatial Extensions".

Examples of WKT representations of geometry objects:

• A Point:

  POINT(15 20)
  

  Note that point coordinates are specified with no separating comma. This differs from the syntax for the SQL POINT() function, which requires a comma between the coordinates. Take care to use the syntax appropriate to the context of a given spatial operation. For example, the following statements both extract the X-coordinate from a Point object. The first produces the object directly using the POINT() function. The second uses a WKT representation converted to a Point with GeomFromText().

  mysql> SELECT X(POINT(15, 20));
  +------------------+
  | X(POINT(15, 20)) |
  +------------------+
  | 15 |
  +------------------+
  mysql> SELECT X(GeomFromText('POINT(15 20)'));
  +---------------------------------+
  | X(GeomFromText('POINT(15 20)')) |
  +---------------------------------+
  | 15 |
  +---------------------------------+
  

• A LineString with four points:

  LINESTRING(0 0, 10 10, 20 25, 50 60)
  

  Note that point coordinate pairs are separated by commas.

• A Polygon with one exterior ring and one interior ring:

  POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))
  

• A MultiPoint with three Point values:

  MULTIPOINT(0 0, 20 20, 60 60)
  

• A MultiLineString with two LineString values:

  MULTILINESTRING((10 10, 20 20), (15 15, 30 15))
  

• A MultiPolygon with two Polygon values:

  MULTIPOLYGON(((0 0,10 0,10 10,0 10,0 0)),((5 5,7 5,7 7,5 7, 5 5)))
  

• A GeometryCollection consisting of two Point values and one LineString:

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