[mapserver-users] Re: WFS intersect request

[Yewondwossen Assefa]

Hi,

On 16/06/2011 7:29 AM, Marco Bagni wrote:
> Dear John,
>
> let me take your request as the occasion to share a thought with this
> community.
>
> You are experiencing my same problem and your last deduction is correct:
> BBOX works, for the rest the mismatch between the available documentation
> and the real implementation of the spatial filters (if really implemented!
> at this point doubting is legitimate) makes impossible for a normal human
> being to sort out how to make the Intersect or other filters work.
>
The docs on this at http://mapserver.org/ogc/filter_encoding.html on 
Spatial operator Intersects 
<http://demo.mapserver.org/cgi-bin/wfs?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=cities&Filter=%3CFilter%3E%3CIntersect%3E%3CPropertyName%3EGeometry%3C/PropertyName%3E%3Cgml:Polygon%3E%3Cgml:outerBoundaryIs%3E%3Cgml:LinearRing%3E%3Cgml:coordinates%3E135.5329,34.6624%20135.4921,34.8153%20135.3673,34.7815%20135.3800,34.6216%20135.5361,34.6210%20135.5329,34.6624%3C/gml:coordinates%3E%3C/gml:LinearRing%3E%3C/gml:outerBoundaryIs%3E%3C/gml:Polygon%3E%3C/Intersect%3E%3C/Filter%3E> 
suggests to use intersect with polygon. It was not revised for some time 
but was working at the time of implementation.

You can also check examples in the the autotest tools; 
http://svn.osgeo.org/mapserver/trunk/msautotest/wxs/ (in wfs_filter.map)

> What is missing is the proper syntax on how to describe the feature
> boundaries that you want to use to perform the spatial filter.
>
> I have seen examples where your "SHAPE" was replaced by "Polygon" but also
> for that statement was not clear how to say what projection (EPSG) use.
>
> Fortunately the given (working) example for the BBOX filter that you can
> find in the documentation is complete (covers also the declaration of the
> EPSG directive) and works.
>
> You and I (and many more users with the same problem) are facing the
> "other side" of the Open Source. Who writes the code and releases it for
> public domain, sometimes arranges things in such a way that, elegantly,
> the users are "suggested" to turn to his commercial consultancy services
> in order to have the information that makes the whole thing work; he has
> to put some bread on his table too!
>
  wow, that is an unfair comment. I think you are very wrong on your 
assumptions and how you think people make a living on open source. Non 
constructive comment here.


Sometime it simply takes time to as answer to questions on the mailing 
list and address every requests. Note that all things put in trac as 
bugs or enhancements are considered at release time and depending on 
time and how critical they are, they are addressed.

> But almost all of the problems that we are facing in this specific area
> depend mostly on us, since I find difficult to think that in so many years
> nobody has tried to apply a Spatial filter different from BBOX.
>
> Most probably these guys used this very list to ask the support from other
> users but when it came the time to "return" something to the user's
> community (for instance the simple howto recipe that solved their
> problem), then all the animosity and kindness shown up in the request
> message, disappeared and the found solution remained in their code without
> being shared with the rest of us.
>
> Let's start to SHARE. Be generous and the community shall become a real
> living thing made of requests and also of solutions (real solution, well
> written and comprehensible to everybody).
>
> Many parts of Mapserver features are well supported by this community and
> the knowledge is already generously shared. This peculiar area (SLD and
> WFS filtering) is not but the solution is within our realm, just share it.
>
I have not tried or  checked your specific issue you sent but reading 
through it,  I did not see a MapServer version. Try it with 6.0. If 
things don't work, provide a sample map/data/test that I can reproduce 
and attach it to a trac bug.


Assefa




-- 
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Assefa Yewondwossen
Software Analyst

Email: yassefa at dmsolutions.ca
http://www.dmsolutions.ca/

Phone: (613) 565-5056 (ext 14)
Fax:   (613) 565-0925
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