WFS Geometry Type

[Frank Warmerdam]

On Tue, 11 Jan 2005 14:55:50 -0600, Simpson <asimpson at i-55.com> wrote:
> Greetings,
>
> Why does a WFS GetFeature on a MULTIPOLYGON return features of type POLYGON?
>
> Thanks for any advice,
> Drew.

Drew,

Hopefully someone else can provide a more
comprehensive answer, but I believe the problem is that
the shapeObj (the internal geometry object for MapServer)
does not support the full OGC simple feature model.  So
if MULTIPOLYGONS are read from something like OGR
they are turned into shapeObjs with a ring for each ring
in each of the original polygons in the multipolygon, but
all distinctions about which polygon the ring came from,
or even which rings are exterior rings are lost.  Then
when the WFS server creates the GML it just creates a
simple POLYGON geometry even though it consists
of multiple distinct polygons.

For MapServer rendering purposes, there is no need
for the full OGC geometry model.  The simplification
only causes problems for stuff like WFS serving.

We see  a somewhat similar issue with WFS attributes
as shapeObj attributes are typeless.

Best regards,

--
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent