[GRASS-user] DEM export problem

[Matthew Perry]

Hey Zack,

  The "r.out.gdal" export tool will just write out raw elevation
values to the pixels. You can check the min/max values of the raster
with:

gdalinfo -mm test_1.tif

My guess is that the output tif is contains accurate data but, since a
16-bit tiff typically doesn't have a color palette, the rendering
program will usually apply a color ramp (typically black->white) from
low->high which is 0 to 65536 for a 16-bit image. So it really depends
on how the rendering application handles the data. Many programs will
let you alter the color ramp to capture the variability in your data.
"r.colors" and "r.out.tiff"  might do the trick.

- matt

On Wed, Feb 27, 2008 at 1:23 PM, Zachary Parisa <zacharyparisa at gmail.com> wrote:
> Hi all,
>  I'm trying to export a resampled dem to Gtiff using r.out.gdal ; I
>  have no problem exporting a slope and aspect file of the same format
>  and origin, nor do I have any problem exporting landsat images...but
>  for some reason I when I export the elevation file it reports that it
>  has completed without error but upon inspection all I have is an
>  empty,black image that is 1.6mb.
>  Trying the same thing with the spearfish data (elevation.10m) yields
>  the same result....except instead of black, the file is green....
>  my command for example:
>  "r.out.gdal input=elevation.10m format=GTiff type=Byte
>  output=/home/zachary/Desktop/dems/test_1.tif"
>
>  If I were to simply change the file to any other raster this works fine....
>
>  Can anyone help me figure out why I can't export any DEM?
>
>  thanks,
>
>  Zachary Parisa
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>



-- 
Matthew T. Perry
http://www.perrygeo.net