[GRASS-dev] r.out.gdal Gtiff output does not preserve color tables

[Patton, Eric]

I'm using today's Grass 6.3.svn source, gdal 1.5.0.

$ gdalinfo --formats | grep "GRASS"
GRASS (ro): GRASS Database Rasters (5.7+)

In Spearfish60:
$ r.info -t elevation.10m
datatype=DCELL

$ g.region rast=elevation.10m -p
projection: 1 (UTM)
zone:       13
datum:      nad27
ellipsoid:  clark66
north:      4928000
south:      4914020
west:       590010
east:       609000
nsres:      10
ewres:      10
rows:       1398
cols:       1899
cells:      2654802

The following commands all produce tiffs that display completely black in off-the-shelf
image viewers in Ubuntu 7.10: (Eye of Gnome 2.20.1, GIMP 2.4.4)

$ r.out.gdal input=elevation.10m output=elevation.10m.tif type=Byte 
$ r.out.gdal input=elevation.10m output=elevation.10m.tif type=Byte createopt="INTERLEAVE=PIXEL" 
$ r.out.gdal input=elevation.10m output=elevation.10m.tif type=Byte createopt="INTERLEAVE=PIXEL,PROFILE=GeoTIFF" 
$ r.out.gdal input=elevation.10m output=elevation.10m.tif type=Byte createopt="INTERLEAVE=PIXEL,PROFILE=BASELINE"

These commands give a completely blank raster in the same image viewers:

$ r.out.gdal input=elevation.10m output=elevation.10m.tif type=UInt16 
$ r.out.gdal input=elevation.10m output=elevation.10m.tif type=UInt16 createopt="INTERLEAVE=PIXEL"
$ r.out.gdal input=elevation.10m output=elevation.10m.tif type=UInt16 createopt="INTERLEAVE=PIXEL,PROFILE=GeoTIFF"
$ r.out.gdal input=elevation.10m output=elevation.10m.tif type=UInt16 createopt="INTERLEAVE=PIXEL,PROFILE=BASELINE"

According to r.out.gdal manual, the type= parameter should be set to either Byte or UInt16 
to preserve the color table. I can't get either type to output anything useful. Using any other 
type causes r.out.gdal to complain that the color tables won't be preserved. What am I missing here?

Even the example from the r.out.gdal manual page produces an error and a tiff that does not display anything:

$ r.out.gdal in=elevation.10m out=ned_elev10m.tif type=Float64 createopt="INTERLEAVE=PIXEL,TFW=YES"
Exporting to GDAL data type: Float64
ERROR 6: SetColorTable() only supported for Byte or UInt16 bands in TIFF format.
 100%
r.out.gdal complete.

Is a tiff without a color table even useful? I'd settle for a lossy, interpolated color table.

Normally I would just use r.out.tiff as a workaround, but I think this module ought to output 
georeferenced tiffs with sane color tables. In any case, I can't use the tiff-with-worldfile 
workaround; I need geotiffs with the projection info written into the header - *with* a color table.

~ Eric.