| # GRASS Help System

## MANAGEMENT OF THE GEOGRAPHIC REGION

GRASS commands can be used to modify the settings of the user's current geographic region. The settings define the geographic boundaries, map projection, coordinate system, and resolution of data sets.

If the user does not explicitly modify these region settings, GRASS will use the default settings established when the user's current location was first set up; these are stored in the DEFAULT_WIND file under the PERMANENT mapset and copied to the file "WIND" in the user's own mapset. However, these settings can be altered using the g.region program, or by simply editing the "WIND" file using a text editor like "vi".

The user may wish to use different settings for different purposes and frequently alter the current region settings. These "tailored" settings can be stored under the "windows" directory, located under the user's current mapset for possible later use.

GRASS commands commonly ignore data falling outside of the user's current geographic region. For example, when the user digitizes with v.digit, only those areas of the map that fall inside the user's current geographic region will be saved to the vector file produced by "v.digit". When the user displays data to the graphics monitor, only map areas within the user's current geographic region are displayed. When raster analysis programs are run on map layers, only those map areas that fall inside the user's current geographic region will be analyzed and included in the resultant raster map layer.

In previous GRASS releases, the "geographic region" was referred to as the "geographic window"; the latter term is now obsolete.

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Automatically created on: Sat Jan 8 06:50:25 2005