[GRASS-user] using grass on rasters without converting?

[Markus Neteler]

Hi Matt,

On Thu, Oct 30, 2008 at 1:07 PM, matt wilkie <maphew at gmail.com> wrote:
>
> Hello Grass World,
>
> As a long time GIS user I've dipped into grass from time to time but never
> in depth. One of the things that's deterred me is the fact that I have a
> large body of data I work with (tens of gigabytes) and the prospect of
> having to convert into grass, process it, and then flip it back out again is
> unappealing.

Sure - also for us :) But it has been solved recently:

r.external - Link GDAL supported raster file to a binary raster map layer.
http://grass.osgeo.org/grass64/manuals/html64_user/r.external.html

...
> I'd love to be able to be able to do the likes of
> "r.shaded.relief input=mydem.tif output=myshade.tif"

Yes, you can do that from 6.4.svn onwards:

r.external [-r] in=/path/to/mydem.tif out=mydem
g.region rast=mydem -p
r.shaded.relief input=mydem shadedmap=myshade
r.out.gdal myshade out=myshade.tif

For r.out.gdal, check which format is appropriate to keep
the color table if desired.

Hope this helps,
Markus