[GRASS-user] Clipping Raster Map

Hamish hamish_b at yahoo.com
Fri Jan 1 19:24:54 EST 2010

> > I doubt it. The most likely reason for a difference is if the current
> > region has a much higher resolution than the display.

>   Shouldn't.

please post the output of

g.region -p
r.info -gs $mapname

how long are we talking about to render here, 2 seconds or 20?

> > Modules which read raster maps normally resample them
> to the current
> > region. The display library then resamples the data to
> the display
> > resolution.
>   That's what I thought, but apparently it's not working properly
> because I'm not doint something correctly.

g.copy only copies files*, it doesn't resample. if your base raster map
is stored in PERMANENT or somewhere else in your mapset search path then
there is usually little need to make a local copy, it will resample on
the fly as needed, at full speed.. "copy" with r.resamp* or r.mapcalc
if you want a new map which really is cropped 

* well, g.copy + vectors are a bit of an exception

>   When I copy the raster DEM from the source directory
> to the project directory (much smaller bounds),

how do you copy it?

> and view the map in the GUI, I see the
> whole map, not the portion only within the project bounds.

the g.region bounds is the important one.

> I've not yet figured out how to overlay the project bounds vector
> map on the raster map.

in the GUI you can drag layers above and below each other to change
rendering order.. 

>   Well, the current region is set appropriately, but I see the entire
> DEM map when I load it, not just the appropriate portion.

from the command line + d.mon, you see what g.region has the current zoom
set to.



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