[Gdal-dev] 'no data' problem with GDAL/Mapserver

[Jeff Bullard]

Mapserver is treating raster 'no data' values like they are all zero.
The 'no data' pixels are being rendered in my [0 - 5) class.  The actual
'no data' value I am using is 200.  I have also tried 9999. 

gdalwarp -ot Int16 -srcnodata 9999 -dstnodata 200 -s_srs '+proj=lcc
+lat_0=25N +lat_1=25N  +lon_0=95W +units=meters' -t_srs '+proj=latlong
+ellps=WGS84  +datum=WGS84 +no_defs'
NETCDF:'/usr/local/degrib/data/ndfd/conus/200612130500.nc:Astro' /usr/local/degrib/data/ndfd/conus/web/out.tif

Openev verifies that the gdalwarp operation was successful and the
out.tif is good.  When I mouse over a 'no data' area openev tells me
"200 [NODATA]".  But when I put this same out.tif into a mapfile layer
the same pixels are rendered as a zero.

  LAYER #  sky raster layer begins here
    NAME         sky
    TYPE 	 RASTER
    DATA         "/var/www/data/raster/%filename%"
    STATUS       ON
    PROCESSING "SCALE=0,220"
    PROCESSING "SCALE_BUCKETS=20"
    CLASS 
      NAME ">95%"
      EXPRESSION ([pixel] >= 0 and [pixel] < 5)
      STYLE
        COLOR 0 0 150  
      END
    END

    CLASS 
      NAME "90-95%"
      EXPRESSION ([pixel] >=5 and  [pixel] < 10 )
      STYLE
        COLOR 20 20 20
      END
    END

    CLASS 
      NAME "85-90%"
      EXPRESSION ([pixel] >= 10 and [pixel] < 15)
      STYLE
        COLOR 40 40 40
      END
    END

    CLASS 
      NAME "80-85%"
      EXPRESSION ([pixel] >= 15 and [pixel] < 20)
      STYLE
        COLOR 70 70 70
      END
    END

    CLASS 
      NAME "75-80%"
      EXPRESSION ([pixel] >= 20 and [pixel] < 25)
      STYLE
        COLOR 90 90 90
      END
    END
  
    CLASS 
      NAME "nodata"
      EXPRESSION ([pixel] = 200)
      STYLE
        COLOR 240	240	240
      END
    END
END #End sky layer