Stefan Schantz wrote:
Hello Frank,
thank you for your explaination. I think, that now i have a small idea,
what the UMN Mapserver is doing with my raster image.
As I wrote, I use gdal_grid to get my raw data.
Is it right, that if I use the output format Geotiff with the option -
ot Byte, i would avoid these rounding errors? (Also long as my values
are <255. At least it seems so.)
In another case the values of the raw data have a range from 0 to 1E7
(and even higher). I have the problem, that the gradient is very high,
so that only 2 classes are shown in picture.
Is there any way for a logarithmic pre processing like 0-3; 3-10; 10-30;
30-100; 100-300; 300-1000; >1000
I tried to set
PROCESSING "SCALE=1,1001"
PROCESSING "SCALE_BUCKETS=1000"
in the hope, that the last buckets will get all values >1000, but this
was thought too simple.
Stefan,
Values outside the scale range are currently treated as not to be classified
and will not get drawn. I can see this makes it hard to handle data with a
broad dynamic range effectively.
My suggestion is to reclassify the data before using it with MapServer.
Alternatively, it would be nice if MapServer had a mode where it directly
classified pixel values instead of doing it via a lookup table (as is
done now) though that could get quite slow.
Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, warmer...@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent
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