GRASS GIS (Geographic Resources Analysis Support System) is a Geographical Information System (GIS) with raster, topological vector, image processing, and graphics production functionality. 

General overview

For a general overview of GRASS GIS, please read this short description.

GRASS GIS is released under GNU General Public License (GPL). If you are not sure about the differences between public domain software, Free Software and proprietary products, you may have a look at this graph describing Categories of Free and Non-Free Software. Eventually, you may also want to read: Why Open Source Software / Free Software (OSS/FS)? by David A. Wheeler.

Getting started guides, tutorials, and FAQs

The manual includes a GRASS GIS Quickstart which helps you to launch the software and the first steps tutorial for the graphical user interface. You are invited to download sample data which are ready to use.

The GRASS GIS community maintains a Wiki collaborative help site which contains getting started guides, tutorials, tips and tricks, FAQs, and a lot more. See for example Temporal data processing!

What can I do with GRASS GIS? - Some examples

Well, I can't get my GIS data into GRASS! Now what?

  • As GRASS GIS supports a wide range of image, raster, vector and sites data formats, you will likely find a module import your data.
  • From the GRASS GIS online manual pages you can get all information about modules, etc.
  • Besides this you may always ask at one of the GRASS GIS mailing listsdon't hesitate!

The GRASS Documentation Project: Tutorials and Books

If you have additional documents for the GDP, please send a mail to GRASS web page team.

What are LOCATIONs and MAPSETs?

A LOCATION is some geographic extent of interest that contains data sets that [should] all be in the same coordinate system. Every location has a PERMANENT directory which stores some basic information about the whole location, and is a good place to park base files. You can think of a location as a data library for a region of interest.

In a MAPSET you can organize GIS maps thematically or geographically or by project or whatever. Every GRASS session runs under the name of a MAPSET. A MAPSET may be a geographical subset or as large as the parent LOCATION. Technically they are subdirectories under any location. In a networked environment with several users working within the same location, mapsets play a special role. Users may only select (and thus modify) a mapset that they own (i.e., have created). However, data in all mapsets for a given location can be read by anyone (unless prevented by UNIX file permissions). The "PERMANENT" mapset usually contains the read-only base maps like the elevation model, while the other locations are readable and writable by their owners. The "PERMANENT" mapset also contains some information about the location itself that is not found in other mapsets (projection info etc.), thus it must exist in every location.

Putting LOCATIONs on a central server, a team can work inside this project database (usually NFS is used).

Enjoy the GRASS Location Wizard!

Looking for sample data?

  • We provide sample datasets for download including data which are already in GRASS format and ready to use and links to external GIS data (raster, vector etc.).
  • See additionally further Online Courses for further help and the online manual pages.

I already know GIS and want to program within the GRASS environment

  • Since GRASS is an open-source GIS, you have full access to the code. We suggest that you get a fresh copy from the GRASS GitHub repository
    Consider to subscribe to the GRASS Developers mailing list.  The GRASS Programmer's Manual is available here. The Python library is explained here.

    If you would like to take part in the GRASS Development. See also the Get involved! page.

Documentation >> First time users | Last change: 02-Jun-2019