[GRASS-user] .e00 to DEM
debeaudette at ucdavis.edu
Wed Jul 8 12:51:17 EDT 2009
On Wednesday 08 July 2009, Nikos Alexandris wrote:
> There is something strange with the values though (they expand from min
> = -32687 max = 32645). Don't have the time to dig further, maybe there
> are details in the meta-data about it (!?).
This looks like an overflow problem. Could it be that this file contains
unsigned 16 / 32 bit integers, but is being read in as signed 16 bit
This used to happen when reading in Arc ASCII grids that contained very large
numbers (> 32768) somewhere other than in the first couple of lines. I am
pretty sure this bug has been fixed-- but I am not sure how GDAL is
interpreting this specific file. It would be useful to use gdal_translate to
copy the file, forcing the bit-size of the output to something else.
Here was the original GRASS ticket: http://trac.osgeo.org/grass/ticket/166
and the subsequent GDAL ticket: http://trac.osgeo.org/gdal/ticket/2369
There are some tips in the GDAL ticket on forcing a file to be read as a 32bit
integers (etc.). Quoth Frank W:
Note that with gdal_translate you can convert pixel types on the fly, so if
you know the data range is suitable for Int16, you could
do "gdal_translate -ot Int16 in.grd out.tif" for instance.
Soil Resource Laboratory
University of California at Davis
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