[mapserver-users] difficulty with negative raster values in WMS

[Smith, Michael]

This seems to be a common problem, yet I find it difficult to get a solution by searching list archives and so forth and hacking at it (4 hours now).

I have slope rasters for a large area - they are slightly overlapping 32-bit float GeoTIFFs.  The images have a 1-pixel border with the value -9999.  Otherwise slope is shown as percent and ranges from 0 to just over 7000%.

I just want to turn off the 'nodata' pixels - those with values -9999 and keep my LUT values as shown below.  I am accessing this a WMS.  MapServer 6.2 (MS4W 3.0.4).

I have tried

PROCESSING "NODATA=-9999"

and

PROCESSING "SCALE=0,7000"

and

PROCESSING "LUT=-9999:0,0:10,50:200,100:225,7000:255"
OFFSITE 0 0 0

And various combinations, etc.  I also tried setting pixel queries using STYLE blocks but that seemed really clunky and I couldn't see how to get what I want.

In the first two cases, it seems like the directives are just ignored.  In the last case I get an error message when I use a negative value in my LUT.

Trying to avoid reprocessing all the tiles...

Thanks for any help.

===============================
Michael Smith MS GISP
State GIS Manager, Maine Office of GIS
State of Maine, Office of Information Technology
michael.smith _at_ maine.gov 207-215-5530

Board Member, Maine GeoLibrary
Education Chair, Maine GIS Users Group
State Rep, National States Geographic Information Council
[cid:image001.jpg at 01CE345E.8DAC1BC0]

State House Station 145
51 Commerce Drive
Augusta, ME 04333-0145
69o 47' 58.9"W  44o 21' 54.8"N
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