[gdal-dev] GML driver - gfs geometry type values and supported GML geometry types

[Even Rouault]

Johannes,

this is more an issue on QGIS side, in its OGR provider where there's 
likely a lack of mapping between the OGR geometry types and QGIS 
geometry types for Curve and Surface (just guessing, didn't check). The 
root cause is that Curve and Surface in OGC/ISO specs are abstract types 
only, not directly instantiable. So it is really hard to have datasets 
where they are reported as layer geometry types, unless you try hard to 
do so, as you did. I'd suggest you use CurvePolygon (resp. 
CompoundCurve) instead of Surface (resp. Curve) in your .gfs file. 
That's what the OGR XSD reader does when encountering a 
gml:SurfacePropertyType or gml:CurvePropertyType. Those are instanciable 
types and QGIS should behave properly

Even

Le 05/01/2023 à 14:00, Johannes Echterhoff a écrit :
>
> Hi,
>
> The GML driver shows behavior that I do not understand: When I load a 
> feature with a gml:Polygon, which, in the gfs file, is defined with 
> GeomPropertyDefn/Type = Surface, then the geometry does not appear to 
> be understood. At least when I try to load the data in QGIS 3.28.0, 
> then the layer has an unknown geometry type. If, on the other hand, I 
> set GeomPropertyDefn/Type to “Polygon”, “MultiPolygon”, or even 
> “MultiSurface”, the geometry is recognized. Same problem if the 
> feature has a gml:LineString as geometry, and I declare it as 
> GeomPropertyDefn/Type = Curve.
>
> What am I missing here? :-)
>
> Is there some documentation available that sheds light on which gfs 
> geometry type values support which GML geometry types?
>
> Best regards,
>
> Johannes
>
>
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