What is GRASS?

3D image/NVIZ tool tcltkgrass NVIZ tool

The GIS GRASS (Geographic Resources Analysis Support System) has been originally developed by the U.S. Army Construction Engineering Research Laboratories (USA-CERL) as a tool for land management and environmental planning fot the military.
Since the beginning it has been developed on UNIX platforms, and it's distributed with the source code.
It is Free Software/Open Source released under GNU General Public License (GPL).
The developement model is the one of the Open Source Software, with developers all-over the world and one coordination center: ITC-irst in Trento, Italy.
Internet is the place where GRASS is distributed to its users, and where developers can interact with users or among them. It's allso the place where documentation, tutorial or help can be found.

GRASS sistem is organized on three levels:

  1. core;
  2. modules;
  3. graphic interface.

GRASS is mainly written in C language, some modules in FORTRAN. The graphic interface uses Tcl/Tk language, and a non-free Motif version also exists.
Modules are structured in groups:

More than 365 modules are available, for the most different purposes, from spatial analysis to environmental modelling, from thematic maps generation to DBMS integration, and 2D or 3D data visualization. Modules number is constantly increasing, due to the possibility to access the source code.

GRASS can handle both vector and raster formats: exchanging data with other GIS is possible using interchange formats like TIFF, gif, IMG, ASCII, ARC/GRID (raster) or DXF, ESRI-E00, ESRI-SHAPE, ASCII, MapInfo (vector) and many more.

A World Wide Web interface called GRASSLinks to distribute GRASS data through internet has been developed by the Research Program in Environmental Planning and GIS (REGIS) of the University of California, Berkeley. This system provides visualization and analysis tools, allowing data sharing and cooperation between users through the internet.

Supported hardware platforms are Linux, Sun Solaris, Silicon Graphics Irix, HP-UX, DEC-Alpha, and Windows 95/98/NT/XP. GRASS developement is based mainly in Linux/Unix environments, so this is the most appropriated "habit" for GRASS usage.
For installation, GRASS requires at least 30 Mb of disk space for the precompiled binaries, the source code package needs around 100 Mb uncompressed; the resulting binaries may need between 80 Mb and 180 Mb depending on the platform, but during a full compilation you need temporarily 550Mb including the source code. 32 Mb of RAM are required (128Mb recommended), and be sure to have at least 500 Mb available on disk for data storage! Some libraries must be installed in order to use all GRASS modules: libtiff, libjpeg, libz for TIFF image importation, libTcl/Tk for the graphic interface, Mesa-3.0 (openGL clone) and lesstif (MOTIF clone).

Didactics with GRASS in the world

GIS GRASS has been adopted in many american and european universities. On-line well-made tutorials are available.

One is the Spatial Analysis course of the Delaware University, where main GRASS commands are described and a particular section is dedicated to UNIX-like operative systems first time users. At the end of the tutorial some exercises are proposed to the users: mining analysis, habitat analysis, hydrological analysis using DTMs, remote sensing and image processing. All required files to do these exercises are inside the SPEARFISH dataset (9.7 Mbytes): a group of raster, vector and sites map of the South Dakota, available for both 4.x and 5.x versions of GRASS on the site grass.itc.it/data.html.

Spearfish dataset uses UTM projection system. On the same page you can find the IMAGERY dataset, including aerial and SPOT satellite images (19.1 Mbytes).
Finally some smaller datasets allow users to experiment some particular GRASS modules, like fire simulation r.ros, r.spread e r.spreadpath commands: to try them download the "Fire simulation dataset" (145kBytes).

Another GRASS tutorial is the one created by the ASSIST Project (Academic Support for Spatial Information Systems) of Leicester University, which is rather old (it's still based on GRASS 4.x) but well structured.
This tutorial is composed by four didactic modules: each one has a duration of two hours, with a little test at the end of every chapter. Lessons and exercises are about population distribution, soil usage, roads and railroads, rivers, DTM, satellite images. It can be downloaded here.

A last tutorial, useful for german language users, is the one of the Geology Institute at Freiburg University.

At this point the former first time GRASS user has now become an expert GRASS user, and can use this GIS to study more complex situations: a good example are the Spatial interpolation, Territorial analysis and Erosion models modules elaborated by the Geographic Modeling Systems Laboratory of Illinois University at Urbana-Campaign, and the module for the automatic detection of outlayers in digital surfaces, developed by the Geomatics Laboratory of the Milan Politecnico.

Didactics with GRASS in Italy

Also in Italy some universities are starting to use GRASS for didactics.
Some examples: a Photogeology course in the Geologic Science Faculty of the University of Parma, a Digital Cartography course in the Engineering Faculty of the Milan Politecnico, Photogrammetry and integrated Ecologic Forest Planning, Environmental Impact Analysis and Digital Cartography courses in the Engineering Faculty of Trento University.
GRASS documentation in italian is available on "GRASS Italian Users" site. Here can be found the e-mail of all registered GRASS italian users, together with a brief description of their activities, and information about events in Italy and all-over the world are always updated. Pubblications regarding GRASS usage or developement are also mentioned on the site.

GRASS Italian User Meetings

The first GRASS Italian User Meeting was held in Como, on the 28th of january 2000, hosted by the Faculty of Engineering of Como. Then a new meeting is held every year with two main purposes: exchanging the knowledge between italian users and allowing potential users to get in touch with some interesting GRASS applications.
The language of the meeting is italian, but proceedings are published in english on "Geomatics Workbooks" by the Geomatics Laboratory of the Milan Politecnico.


Università degli Studi di Trento - Facoltà di Ingegneria