[GRASS-user] Region Definition in GRASS

[Glynn Clements]

Pedro Roma wrote:

> I'm a kind of a new GRASS user and I'm a bit lost on regarding something.
> REGION (or spatial extent).
> For instance the Location North-Carolina. When the location was created a
> certain extent, projkection a Spatial Resolution was defined. But, inside
> this location there is a lot of data with different extent and regional
> cover. And, inside GRASS I can re-define region properties (g.region) and
> use a certain data to define region. And, it's possible to have a region
> with a small extent than a vectorial that exists in the Location.
> My question is, what is the region and what is its purpose? Because I don't
> see any impact of region over my image/data processing or image
> visualization. Or is it?

The region is mostly used for raster processing and graphical display.

Most commands which read or write raster maps will use the bounds and
resolution from the current region. Any input maps will be cropped,
padded and/or resampled according to the region settings.

Display commands translate geographic or cartographic coordinates to
display coordinates such that the current region just fits inside the
display window.

Vector commands are normally unaffected by the current region.

-- 
Glynn Clements <glynn at gclements.plus.com>