[postgis-devel] patch : TIN & POLYHEDRALSURFACE

[Mathieu Le Serre]

Hi,

A few month ago, we already discussed here about 3D storage and PostGIS,
(cf
<http://postgis.refractions.net/pipermail/postgis-users/2007-April/015166.html>)
 
We made a patch to add such new geometries to PostGIS.

It implements TIN and POLYHEDRALSURFACE as described in
OGC SFS1.2 standard.
These geometries are specific MULTIPOLYGON that
describe 3D surfaces and 3D volumes.

Currently, we got the following functions to work for 3D geometries:
- asEwkb
- asEwkt
- asGml
- asSvg (2D output only)
- asX3d.

This last function enables exporting 3D geometries to the X3D format.

I also provide a patch for GEOS to implement the isValid function
for TIN and POLYHEDRALSURFACE. It checks if feature faces
are well connected and well oriented.

A presentation around this work will be done in FOSS4G
<http://www.foss4g2007.org/presentations/view.php?abstract_id=224>

PostGIS implementation consideration:
There were already 15 geometries types and I needed to add two. But geometry
types were coded on 4 bits only...
In order to implement these geometries,  I decided to drop three unused
geometry types (POINTTYPEI, LINETYPEI, and POLYGONTYPEI).
They were not present in the postgis parser, and were described as
"Invalid types" in the file liblwgeom.c.


Any comments and/or reactions would be greatly appreciated.
  

Best regards,

 
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