This month we bring back one of our regular series, Free for All – are you are excited as we are?! ..crickets…
Although the most commonly used GIS software is expensive (i.e. ArcGIS), there are robust free options. Free software, also known as FOSS (Free Open Source Software), is available to all, and often has open source code to allow for improvements by the public. As the community involved in geospatial data and GIS expands, so has access to open-source software. In order to save you time that could be spent sorting through the different options, I will cover the top 3 as reported by various online reviewers.
The consensus among several different blog sites, as well as reviews, is that QGIS is the top free option for GIS. In terms of overall functionality, it covers all the bases. It supports a wide variety of spatial formats, and has a user-friendly Python interface which allows for the easy addition of new plugins. Also, there is a significant amount of documentation, located in the user manual, as well as a very active community, which helps users overcome mapping obstacles. It allows for automated map production (model building), geospatial processing, advanced cartographic design, data management and much more (see this article which touches on 27 comparisons between ArcGIS and QGIS). The fact that QGIS is comparable to ArcGIS (and is still completely free) goes to show that money is not the only inspiration for quality software, rather a committed and generous community can create tools that are just as useful and capable.
The other recommended free GIS packages are not as capable as QGIS as they are tailored to be used for specific tasks such as terrain or statistical analysis, those being GRASS and SAGA. GRASS (Geographic Resources Analysis Support System) was originally developed by the US Army Corps of Engineers in 1982 for land management and planning. Since then, it has been expanded into a powerful toolkit for image processing and analysis, as well as for terrain manipulation, that is used by many agencies including NASA, NOAA, USDA and NPS.
SAGA (System for Automated Geoscientific Analyses) is another free GIS software package that is useful for terrain analysis, with tools for visibility analysis, watershed extraction and hillshading. Although it may not be the best for cartographic design, its user-friendly interface and plethora of tools allow for efficient geospatial analysis.
While these three options may be the most popular with the best online reviews, there are other free GIS packages that may be better tailored to your project. With your exact use case in mind, I recommend checking out this article for a wider ranging review of free GIS options.
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