[mapserver-users] raster query strategy

[Richard Greenwood]

On Tue, Aug 17, 2010 at 2:57 PM, Frank Warmerdam <warmerdam at pobox.com> wrote:
> Jan Hartmann wrote:
>>
>>  Is this a bug? Shouldn't MapServer use the gdaladdo overviews at the
>> appropriate scales?
>>
> Rich / Jan,
>
> No, generally I treat raster query as an "exact" operation done
> against the full resolution data.  The overviews are only used
> to satisfy downsampled RasterIO requests such as drawing a reduced
> resolution map.

I wouldn't classify it as a bug, but it is an interesting question.
Displaying a map at 1:1,000,000 the user clicks and gets 30,000 cells
from my 10m grid. Which one is right, or "exact"? Right now I'm
averaging them, which is pretty much what gdaladdo has already done.


-- 
Richard Greenwood
richard.greenwood at gmail.com
www.greenwoodmap.com