I can confirm this also with the new data set and ArcGIS. It looks like
r.out.gdal does not "see" the correct region and when the region is set
to the raster it adds one no-data row (or column - I don't remember now)
which is some huge negative number and that may be screwing up
the colors. I think that when my region was set smaller than the raster
the subset of data was OK - but I would have to check.
For convenience, it would be useful to add a flag to r.out.gdal to
export the entire raster map not just a subset given by the region.
Helena
On Feb 27, 2008, at 1:09 PM, Patton, Eric wrote:
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.
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