[GRASS-user] geotiff and tiff exprot

[Hamish]

maven apache wrote:
> Hi all :In fact I have post this
> question,but not got a answer/
> I am using win grass 6.3, when export the raster
> data to tiff ,I can use two command
> >1
> 1) r.out.gdal  use this command the tiff I got
> is blank,and I am sure that this tiff has the correct crs,
> since I have use the gdalinfo command to test the black
> blank tiff.

Markus Metz (et al.) has done quite a bit of work on that module,
hopefully in the latest releases it behaves a bit better for
awkward cases.

for now, check if the GeoTiff actually contains data -- it might
just be the coloring which is misleading but the data is ok.

try:
  gdalinfo -stats file.tif

are the Minimum=, Maximum=, and Mean= reasonable values?


> 2) r.tiff  use this command the tiff I got has
> not crs (Coordinate System),although I can see the data(the
> lines of the road, it is not blank).
> And before I export the data,I use the g.region
> command to identifier the region.

r.out.tiff has a -t flag which will create a "World File" which
can be used for (numeric) georeferencing. To set a CRS you would
have to use "gdal_translate -a_srs".


also d.out.file can create geotiffs, but it is a rather
different animal than the r.out.* modules so read the help
page carefully.


Hamish