[GRASS-user] tiling and 'cliping' DEMs

[Helmut Kudrnovsky]

Rich Shepard wrote
> I am downloading and importing 1m LiDAR DEMs for a 667 mi^2 (1727.5 km^2)
> drainage basin. These are all in 7.5' topographic quad sections. The files
> take up a lot of disk space and memory when working with them.
> 
> I assume that by careful setting of the region I can display the
> individual
> maps as a single map, and I can set a computational mask using the vector
> basin watershed (boundary). Is there way to 'clip' the DEM using the
> watershed map in the way that v.clip works with two vector maps? While the
> workstation has 32G RAM and 2T of disk space I would like to limit the DEM
> to the drainage basin itself and exclude all areas outside it.
> 
> Looking at all the r.* modules in core and extensions none strikes me as
> the
> appropriate tool.
> 
> I'm open to advice on working with huge raster files.
> 
> Regards,
> 
> Rich
> _______________________________________________
> grass-user mailing list

> grass-user at .osgeo

> https://lists.osgeo.org/mailman/listinfo/grass-user

To save diskspace,, build a virtual raster with your tiles outside GRASS  by
GDAL's  buildvrt, do r.external yourvirtual.vrt.

No import is needed for raster calculations, r.external to link the virtual
raster works nicely..

regarding to clip a raster to  vector extent, there a several ways. One may
be: g.region  -a raster=yourraster vector=yourvector followed by a r.mask
vector=yourvector then r.mapcal clippedraster=yourraster 



-----
best regards
Helmut
--
Sent from: http://osgeo-org.1560.x6.nabble.com/Grass-Users-f3884509.html