[postgis-devel] patch : TIN & POLYHEDRALSURFACE

[Robert W. Burgholzer]

Mathieu,
My reaction is that this is a very good thing indeed. Some of the issues
regarding rasters, at least in terms of elevation rasters, could be ameliorated
with the TIN approach.

My $0.02,
r.b.

Quoting Mathieu Le Serre <mathieu.leserre at camptocamp.com>:

> 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,
>
>
>


--
Robert W. Burgholzer
--
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