[GRASS-user] Unable to load gdal library error

Hamish hamish_b at yahoo.com
Wed Sep 22 23:36:51 EDT 2010

Daniel wrote:
> I compiled Grass 6.5 svn from source in Ubuntu 9.10 and it was
> apperently working OK. I then loaded a bunch of srtm tiles using
> r.external but, when I tried to patch them with r.patch I recieved the
> message: ERROR: Unable to load GDAL library. I also cannot display the
> srtm tiles imported using r.external in the Grass Map.

no idea, but check that gdalinfo, gdalwarp, gdal_translate, etc still work.

> However, I can iimport the srtm tiles using r.in.gdal and then raster
> display works fine. My idea is to bring several SRTM tiles in grass
> using r.external and then use r.patch. I was hopping not to use
> r.in.gdal in order to save disk space...

GDAL comes with a nifty little app called "gdal_vrtmerge":

if you feed it all your SRTM tiles, it will virtually patch them together,
and then you can use gdal tools or r.in.gdal on the virtual mosaic.

this is really great for running with "gdal2tiles" for an instant
OpenLayers browser of all the data.

finally, if you put gdal_vrtmerge together with (a functioning..)
r.external, you hardly have to take up any more disk space than the
raw data files. Great for massive data caches where duplicates & disk
space is an issue. If disk I/O is a limiting factor, probably it's faster
to process too.



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