PROCESSING "LUT=.... issue

[Frank Warmerdam]

A.Th.C. Hulst wrote:
> Dear all,
> 
> I have been working on a method to display my freshly computed netCDF data 
> through mapserver and are finally there. However, I find one last issue with 
> the scaling / processing lut= combination.
> 
> Please see the map on http://mapserver.argoss.nl. The mapserver is svn 
> revision 6353. There is a white spot on there that should be red. See the 
> relevant map section below:
> 
>  LAYER
>     NAME "Hs"
>     DATA "netCDF:<SNIP>windwave/ww3_output.nc:sign_wave_height"
>     PROCESSING "SCALE=0,10"
>     PROCESSING "SCALE_BUCKETS=200"
>     PROCESSING "BANDS=1,1,1"
>     PROCESSING "LUT_1=96:0,157:255,221:255,255:240"
>     PROCESSING "LUT_2=29:0,93:255,157:255,221:0,255:0"
>     PROCESSING "LUT_3=28:255,93:255,157:0,255:0"
>     TYPE RASTER
>     STATUS ON
>     OFFSITE 0 0 0
>   END
> 
> The data in this layer is in [0 13.457]. I want to scale the image to [0 10] 
> because more details of lower waves show. What happens is that the RGB values 
> in the area that is clipped (eg Hs > 10m) are set to 255, regardless of 
> anything in the PROCESSING instruction.
> 
> Am I overlooking something or should I report a bug (or feature ;) )?

Sander,

Do you have a sense where things are going wrong?  Is it the scaling or
the LUT application?

I will note that the lut management code assumes that 0 maps to 0 and
255 maps to 255.  So I don't think your 255:0 specifications are
going to work.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org