[mapserver-users] Raw Data Output

[Frank Warmerdam]

Stepan Kafka wrote:
> As to me, I consider very useful to enable process original raw raster data
> via classes rather than output them in raw format, for instance enabling
> this class expression:
> 
> CLASS
>   NAME 'Elevation greater than 2000'
>   EXPRESSION ([pixel] > 2000)
>   color 200 150 0
> END

Stephan,

I agree that this would be desirable; however, the direct implementation of
this idea would involve evaluating the expression for every pixel to be
displayed that comes from the source raster.  This could be pretty expensive
to be doing in a web environment!  The current approach of applying
classifications is to classify the 256 values between 0 and 255 and to force
everyting to this range before running it through the "classified" lookup table.
This is relatively fast.

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