[mapserver-users] transparency in a geotiff

[John Cartwright - NOAA Federal]

Hello All,

I have a geotiff w/ Float32 values ranging from -1.5 to 10329.613.
I'd like to use this for a WMS layer and display pixel values <= 0 as
transparent.

I've tried various permutations of the WMS request options, LAYER
processing directives, and OUTPUTFORMATs but seem to be unable to
achieve my goal.

This is mapserver 6.0.1 and I've listed below excerpts from the current config.

I'd be very grateful for any help or suggestions!

--john


WMS request:

http://mapserver3.ngdc.noaa.gov/cgi-bin/public/viirs?request=getmap&service=wms&layers=SVDNB_npp_d20120913_t0708483_e0721359_b00001_cspp_dev.rade9.tif&bbox=-180,0,0,90&srs=EPSG:4326&width=1000&height=500&styles=&version=1.1.1&format=png&bgcolor=0x000000&transparent=true


OUTPUTFORMAT
  NAME "png"
  DRIVER AGG/PNG
  MIMETYPE "image/png"
  IMAGEMODE RGBA
  EXTENSION "png"
  FORMATOPTION "GAMMA=0.75"
  TRANSPARENT ON
END


LAYER
   DATA "/geotiffs/SVDNB_npp_d20120913_t0708483_e0721359_b00001_cspp_dev.rade9.tif"
   DUMP TRUE
   METADATA
      "wcs_label"
"SVDNB_npp_d20120913_t0708483_e0721359_b00001_cspp_dev.rade9.tif"
      "wcs_rangeset_name"       "Range 1"
      "wcs_rangeset_label"      "viirs"
      "wcs_resolution"  "0.008333 -0.008333"
      "ows_srs" "EPSG:4326"
      "wms_title"
"SVDNB_npp_d20120913_t0708483_e0721359_b00001_cspp_dev.rade9.tif"
   END
   NAME "SVDNB_npp_d20120913_t0708483_e0721359_b00001_cspp_dev.rade9.tif"
   PROCESSING "SCALE=63,0"
   PROJECTION
      "init=epsg:4326"
   END
   TYPE RASTER
   UNITS DD
END