Concepts

Concepts#

Database model#

GRASS GIS has a very special database model which is the main difference to other GIS software.

Database#

  • A normal directory which contains the data you process using GRASS GIS.

Location#

  • A location is a directory with data related to a certain geographic location or a certain project.

  • A location is defined by its coordinate reference system and geographical boundaries.

  • All data within one location must have the same coordinate reference system.

Mapset#

  • A location contains mapsets.

  • Each mapset contains data related to a specific task or user.

  • A user can only work in one mapset at a time.

  • Every location contains a PERMANENT mapset.

  • Data in other mapsets are not accessible, except for the PERMANENT mapset which is accessible from all mapsets.

Important

Never edit files within a mapset outside of GRASS GIS to avoid corrupting the data!

However, you can share a location folder with someone else, as long as you do not edit its contents.

Region#

The region (marked in red) defines the geographic extent within which data is processed. The region is defined by

  • the geographical projection

  • the geographical extent

  • the spatial resolution of cells (only relevant for raster data)

The region can be printed and changed using the command g.region

Resources#

GRASS GIS documentation: https://grass.osgeo.org/grass83/manuals/grass_database.html

Contents