extra spatial filter for OVF source

Huub Fleuren hfl at HOME.NL
Wed Mar 22 13:46:23 EST 2006

Hi Frank,

We would indeed want to use it dynamically, with MapServer. I was 
allready thinking about generating the complete OVF files (one per 
signed on user) by the application, and then supply the filename by 
substitution variable. Now, only the bounding box values are passed thru 
to the mapfile.
e.g.        <SrcSQL>SELECT * FROM kpxy WHERE (x &gt; %xmin%) and (x &lt; 
%xmax%) and (y &gt; %ymin%) and (y &lt; %ymax%) </SrcSQL>

A static extract may also be usable for the time being, because at the 
moment selections other than rectangular shaped are rare.


Frank Warmerdam wrote:

> Huub Fleuren wrote:
>> Hi List
>> http://www.google.com/search?hl=en&lr=&rls=GGLD%2CGGLD%3A2004-28%2CGGLD%3Aen&q=ODBC+gdal+spatial+filters+VRT+format+howto 
>> I was hoping that i could put an extra spatial filter (a polygon : 
>> find all point within the polygon) to the following OVF source
>> Is it possible?
>> How?
> Huub,
> I don't know how this would be accomplished without changing some code,
> though I can see that it would be an interesting capability for the OGR
> VRT (OVF) driver.  If you just wanted a one time static extract it 
> wouldn't
> be to hard to setup with a Python script but doing it dynamically is
> not currently supported.
> Best regards,
>> Thanks in advance
>> <OGRVRTDataSource>
>> <OGRVRTLayer name='wwal'>
>>    <SrcDataSource>ODBC:admin/admin at anwb</SrcDataSource>
>>        <SrcSQL>SELECT k.kp_nr as kp_nr,k.x as x, k.y as y, 
>> w.wegbeheerdercode as wegbeheerdercode, w.onderhoudsinstantiecode as 
>> onderhoudsinstantiecode FROM wwall w, kpxy k WHERE NOT (k.soort LIKE 
>> 'D') and (w.x &gt; 190000) and (w.x &lt; 200000) and (w.y &gt; 
>> 500000) and (w.y &lt; 520000) and (w.kruispuntnummer = k.kp_nr)</SrcSQL>
>>    <GeometryType>wkbPoint</GeometryType>
>>    <LayerSRS>WGS84</LayerSRS>
>>    <GeometryField encoding='PointFromColumns' x='x' y='y'/>
>> </OGRVRTLayer>
>> </OGRVRTDataSource>

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