Over the last few years the world of free and open source geospatial software has experienced some major changes. For instance, the website FreeGIS.org currently lists 330 GIS related projects. Besides the advent of new software projects and the growth of established projects, a new organisation known as the OSGeo Foundation has been established to offer a point of contact. This paper will give an overview on existing free and open source desktop GIS projects. To further the understanding of the open source software development we give a brief explanation of associated terms and introduce the two most established software license types: the General Public License (GPL) and the Lesser General Public License (LGPL). After laying out the organisational structures, we describe the different desktop GIS software projects in terms of their main characteristics. Two main tables summarise information on the projects and functionality of the currently available software versions. Finally, the advantages and disadvantages of open source software, with an emphasis on research and teaching, are discussed.
The development of free and open source software has experienced a boost over the last few years. The variety of Free and Open Source Software (short: FOSS) that can be found on desktop computers ranges from word processors (e.g. OpenOffice.org), web browsers (e.g. Mozilla Firefox) to drawing (e.g. Inkscape) and scientific applications (e.g. R Project). In the GIS domain, the widespread use of FOSS is apparent as well. This rise in popularity of free GIS tools can be measured using four indicators. The first indicator is the number of projects started in the last couple of years. For instance, in last two years 20 entries have been added to the list of software projects on the website FreeGIS.org (containing now 330 entries). As a second indicator, we see the increasing financial support by governmental organisations for the foundation of FOS GIS projects. Our listing of desktop GIS projects provided below shows that governmental funding supports at least 4 out of 10 projects. The third indicator is the download rates of free desktop GIS software. SAGA GIS for instance experienced an average increase of downloads in its documentation section between 2005 and 2008 from 700 to 1300 per month1. Finally, a fourth indicator is an increasing number of use cases of open source GIS software such as those documented by Ramsey (2007a) for the geospatial database PostGIS.
Along with this trend towards the application of open source software goes the number of research publications that mentions the use of open source software tools and libraries (see for instance Mitasova and Neteler 2004). Furthermore, software and algorithms developed in research projects are increasingly being published under open source licenses (e.g. Badard and Braun 2003, Pebesma 2004, Burghardt et al. 2005, Buliung and Remmel 2008). As such, it is important to note that the free and open source software movement that postulates the freedoms of use and modification for software is not restricted to software only. Rather one regards free software as “the foundation of a learning society where we share our knowledge in a way that others can build upon” (FSF 2008a). Hence, this movement also includes the free availability of data that forms a basis for our knowledge. Certain initiatives that focus especially on the free availability of geodata do exist (see FreeGIS.org)2. Probably the best known project is the OpenStreetMap Project. This movement of free software and data is further facilitated by (online) platforms such as Sourceforge.org, which provide an environment for software development, Eduforge.org, which aims to foster the sharing of ideas, research outcomes, and open content for education, as well as the Open Knowledge Foundation (okfn.org) and ScienceCommons.org, which both provide strategies and...
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