WKT: how do you define polygons with three rings (== 2 holes)?

Question

I found this document here . I read it, but I keep wondering how to define a three-ring polygon in WKT ?

Answer 1

You can use either the POLYGON type or the MULTIPOLYGON type, but be sure to specify the outer container ring first and then the inner rings. The orientation of the inner rings is not important, since the holes are explicit in the syntax.

X Y , , . ( ) .

, .

:
((10 10, 110 10, 110 110, 10 110), (20 20, 20 30, 30 30, 30 20), (40 20, 40 30, 50 30, 50 20))
(((10 10, 110 10, 110 110, 10 110), (20 20, 20 30, 30 30, 30 20), (40 20, 40 30, 50 30, 50 20)))