[Mapserver-users] Query Raster Layer for Pixel Values

[Frank Warmerdam]

John Norton wrote:
> Sorry I missed the meeting in Ottawa. Frank W. probably discussed 
> querying raster layers in his workshop. Basically, I would like to a 
> query a raster layer (8 bit or 16 bit if possible) with a bounding 
> rectangle or possibly a user selected/defined shape and apply a function 
> to each of the pixel values, eg find the average value. Or could a query 
> just return a vector with the pixel values. I don't need the spatial 
> location for each, just the DN value. Any ideas how this may be done 
> with MS or where might I start?

John,

I would suggest you start by reading over the wiki topic:

   http://mapserver.gis.umn.edu/cgi-bin/wiki.pl?RasterQuery

Basically, you can use normal query by point, rect or shape against raster
layers, but you need to include a template for the raster layer.  The results
can be displayed using a template, or consumed in mapscript.

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