[Mapserver-users] Mapserver and GML.

[Frank Warmerdam]

Andrew Larcombe wrote:
> Hello all.
> 
> I have some questions about the use of GML within Mapserver. I am going to
> produce a schema for some data which contains geographical data. I
> understand that Mapserver uses OGR to read GML and I've read Frank
> Warmedam's "Practical GML Interoperability" -
> http://gdal.velocet.ca/~warmerda/projects/gml/gml_interop.html - although
> I'm  not sure how old and still relevent the document is.
> 
> My questions basically boil down to: 1. Which versions of GML does
> Mapserver support? 

Andrey,

The GDAL/OGR library essentially supports GML 2 (though relatively simple
GML 3 files should work too).  Note that GML *generation* from MapServer
goes through a completely different mechanism, so I am just speaking about
GML consumption by MapServer via GDAL/OGR.


 > 2. Can I use 3-d coordinates, and if so how are these handled?

OGR should have no problem consuming 3D GML data.  However, I am not
aware of any meaningful way to make use of the Z coordinates in MapServer.

> 3. Can I use the Mapserver CLASS to select a subset of records
> within the GML to display?

Yes.  All recognised attributes from the GML file should be carried through
for normal processing in mapserver.  I would suggest you use "ogrinfo" to
show you what OGR sees in your GML file (layers, attribute names, etc).  Then
construct classes, filters and so on accordingly.  You should also read over
the MapServer OGR HOWTO if you haven't already.

PS. The Practical GML Interoperability document isn't particularly refined,
nor does it reflect current OGR operation all that closely.

Good luck,

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