[mapserver-users] processing scale=auto with float multibands rasters

[Even Rouault]

On Monday 03 August 2015 11:02:43 Andrea Peri wrote:
> Hi,
> I have a geotiff multibands with float64 values to serve with a wms
> mapserver service.
> 
> With this kind of rasters,
> is affordable the directive
> 
>     PROCESSING "BANDS=4,3,2"
>     PROCESSING "SCALE=AUTO"
> 
> (the 4,3,2 are the red,green,blue channels)
> 
> Infact it seem do nothing.
> 
> Instead all work well if I set:
> 
>     PROCESSING "BANDS=4,3,2"
>     PROCESSING "SCALE_1=0.01,0.2"
>     PROCESSING "SCALE_2=0.01,0.2"
>     PROCESSING "SCALE_3=0.01,0.2"
> 
> where ii use the min=0.01 and max=0.2
> But I like to have the exact values of min/max for every raster.

Andrea,

SCALE=AUTO should work but looking at the actual implementation I can see it 
computes the min/max on the pixel values intersecting the requested area, and 
not on the whole raster as I'd have expected. So in a tiling context, it will 
likely not produce the expected result.

Even

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