Explain Interior, Boundary and Exterior

[mloskot]

For completeness, it would be good to give short description of these three fundamental terms in the PostGIS manual:

The IBM Informix manual provides short but clear definitions of ​Interior, Boundary, and Exterior:

All geometries occupy a position in space defined by their interior, boundary, and exterior.
 * The exterior of a geometry is all space not occupied by the geometry.
 * The boundary of a geometry serves as the interface between its interior and exterior.
 * The interior is the space occupied by the geometry.

PostGIS manual could include similar.

[kneufeld]

First draft is here: ​http://www.postgis.org/documentation/manual-1.5SVN/ch04.html#DE-9IM

[mloskot]

Kevin,

This is (uncensored word here ;-)) brilliant! I got way more than I asked for.

Just a few typos:

• eachother
• desireable

Perhaps Read from left to right could be completed with and from top to bottom too.

Also, I think it could be useful to add source reference to the Topogical/Clementini operators, PDF at ​Dimensionally Extended Nine-Intersection Model (DE-9IM) by Christian Strobl

Thank you!

[mloskot]

...or non-URL reference to "Encyclopedia of GIS" By Hui Xiong where it is DE-9IM perfectly explained for everyone who wants to dig details.

[kneufeld]

Thanx Mateusz. I fixed the typos and add your noted references at the end of the section.

I like the pdf doc by Christian Stobl. Nice. I hadn't seen that one before. I was thinking along the same lines and would eventually like to see a simple de9im matrix in every spatial predicate definition (touches, crosses, within, etc) just as Christian has done in his doc. ... someday :)