[mapserver-dev] Re: problem with WFS DWithin

[Paul Ramsey]

DWIthin(A, B, D)

should be functionally identical to

Distance(A, B) < D

so no, what you describe doesn't sound like a correct DWithin, Bart.
BTW, if it's implemented as

Intersects(A, Buffer(B, D))

it's incredibly inefficient.

P.

On Thu, Mar 27, 2008 at 8:19 AM, Bart van den Eijnden (OSGIS)
<bartvde at osgis.nl> wrote:
> Okay, it seems it only returns features if they are totally contained within
>  the searchshape + distance (the buffered linestring).
>
>  Is this the way DWithin is supposed to behave? I am not a geometry operator
>  specialist unfortunately, but my expectation was to get any of the polygons
>  containing the buffered linestring.
>
>  A small buffer (500 m) selects nothing:
>  http://www.osgis.nl/download/umn/dwithin1.png
>
>  A bigger buffer (2500 m) only selects 3 polygons:
>  http://www.osgis.nl/download/umn/dwithin2.png
>
>  Best regards,
>  Bart
>
>  --
>  Bart van den Eijnden
>  OSGIS, Open Source GIS
>  http://www.osgis.nl
>
>
>  --------- Oorspronkelijk bericht --------
>  Van: Bart van den Eijnden OSGIS <bartvde at osgis.nl>
>  Naar: mapserver-dev at lists.osgeo.org <mapserver-dev at lists.osgeo.org>
>  Onderwerp: problem with WFS DWithin
>  Datum: 27/03/08 14:59
>
>  >
>  > Hi list,
>  >
>  > I can't get a DWithin filter containing a LineString to work. I am using a
>  > polygon layer. It doesn't select anything. Using 5.0.2.
>  >
>  > A DWithin containing a Polygon works fine.
>  >
>  > Any ideas what could be causing this?
>  >
>  > Did anybody else experience the same thing?
>  >
>  > Best regards,
>  > Bart
>  >
>  > --
>  > Bart van den Eijnden
>  > OSGIS, Open Source GIS
>  > http://www.osgis.nl
>  >
>  >
>  >
>  >
>
>
>
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