[postgis-users] X3D and Postgis

[Olivier Courtin]

On Wed, 4 Apr 2007 10:36:29 +0100
"Martin Daly" <Martin.Daly at cadcorp.com> wrote:


> OGC Simple Features 1.2 (snip URL)
> introduced POLYHEDRALSURFACE and TIN 

Yeap that's sound great !

The only lack on this TIN storage is that it's still not really 
a topological one...

(from 7.2.6 section)

Tin Z (
((0 0 0, 0 0 1, 0 1 0, 0 0 0)),
((0 0 0, 0 1 0, 1 0 0, 0 0 0)),
((0 0 0, 1 0 0, 0 0 1, 0 0 0)),
((1 0 0, 0 1 0, 0 0 1, 1 0 0)),
)

So each triangle will use in fact 4 points (the fourth one to close
the ring)

And a lot of identical points are stored several time in this TIN
geometry...

The good new is that is in someway handled by the spec... :) 

-- 
Olivier