[gdal-dev] Bogus <gml:Face> interpretation

[strk]

On Sun, Jan 30, 2011 at 05:53:20PM +0530, Chaitanya kumar CH wrote:

> Thank you very much for pointing out the errors. I could blame it on the
> lack of enough sample data but that's just laziness. I should have read the
> specifications more throughly.

I noticed primarly because the GDAL interpretation would have not map
1:1 with the ISO SQL/MM topology model implemented in PostGIS.

> I see your first point but I need to dig deeper for the second.

The second point is not very clear in the GML document.
About TopoSurface, it says:

 `` gml:TopoSurface represents a homogeneous topological expression,
    a set of directed faces, which if realized are isomorphic to a
    geometric surface primitive. ''


I'm guessing that "realizing the set of" (F1,F2) means deploying it,
or "burning" it, "filling" it.... "unioning" it.

> >  +------+------+
> >  | F1   |  F2  |
> >  +------+------+
> >
> > A surface/polygon formed by the two faces above (F1,F2) should be
> > represented as:
> >
> >  <TopoSurface id="P1">
> >   <directedFace> <Face id="F1"/> </directedFace>
> >   <directedFace> <Face id="F2"/> </directedFace>
> >  </TopoSurface>


The simple geometry resulting from the above would be this:

     +-------------+
     |     P1      |
     +-------------+

--strk; 

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