GRASS (Geographic Resources Analysis Support System) is a public domain
raster based GIS, vector GIS, image processing system, and graphics
production system. Created by the US Army Corps of Engineers,
Constriction Engineering Research Laboratory (USA/CERL) and enhanced by
many others, it is used extensively at government offices, universities
and commercial organizations throughout the world. It is written mostly
in C for various UNIX based machines. Linux is one of its more robust
implementations.
GRASS contains over 40 programs to render images on monitor and paper;
over 60 raster manipulation programs; over 30 vector manipulation
programs; nearly 30 multi-spectral image processing manipulation
programs; 16 data management programs; and 6 point file management
programs.
GRASS' strengths lie in several fields. The simple user interface makes
it an ideal platform for those learning about GIS for the first time.
Users wishing to write their own code can do so by examining existing
source code, interfacing with the documented GIS libraries, and by using
the GRASS Programmers' Manual. This allows more sophisticated
functionality to be fully integrated within GRASS.
Other strengths include GRASS' pioneering of mixed resolutions in a data
base, mixed geographic coverage areas in a data base, raster image
compression techniques via run-length encoding and reclassification
lookup tables, GRASS' rescaling of display images on the fly to fill the
display screen, plus its fundamental design criterion of powerful
computer-assisted scientific analysis of environmental issues (as
opposed to merely going for intricate cartographic output of relatively
simple processes).
GRASS is usually supplied as free, non-copyright source code to be
compiled on host machines. Some compiled binaries are also easily
obtainable at no cost via the Internet. It runs on a variety of UNIX
platforms.
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Intro to GRASS.
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