PrintWhile in lessons 1 and 2 we mainly focused on advanced Python programming approaches within the ESRI ArcGIS world, lesson 3 involved a step away from proprietary GIS software towards open source Python libraries and software tools, even though one of the main points we wanted to make in this lesson was that both worlds are not as separated as one might think. In this final lesson of the course, we will be leaving ArcGIS behind completely and take a closer look at the open source alternative QGIS, a free desktop GIS that most likely you have already heard of.
While the history of open source GIS software goes back more than 30 years, open source desktop GIS software has only very recently reached a level of maturity and intuitive usability that can be considered comparable to proprietary desktop GIS software. With desktop GIS software we mean standalone software that can be installed and run locally on a computer and that makes the most common GIS data manipulation and analysis functionalities (for at least both raster and vector data) accessible via an easy-to-use GUI, similar to the ArcGIS Desktop products. However, these days there do exist multiple such open source alternatives, including the ones we briefly list below:
Grass GIS
Grass (Geographic Resources Analysis Support System) is the ancestor of open source GIS but is still under active development, with a history of more than 30 years. Its development was started by the U.S. Army Construction Engineering Research Laboratories in 1982 but it is now maintained by the Open Source Geospatial Foundation (OSGeo) under GNU GPL license. Grass is largely written in C/C++ and provides a large collection of GIS tools grouped into modules. Other open source GIS systems, such as QGIS for example, integrate these GRASS modules to extend their functionality.
gvSIG Desktop
gvSIG Desktop is a much younger open source software by gvSIG Association written in Java. Its initial release was in 2004. Similar to Grass, it is published under the GNU GPL license. The most recent version (at the time of this writing) is 2.5.1 released in March 2020.
MapWindow GIS
MapWindow is an open source project that, in contrast to most of the others listed here, is only available on Windows. It is written in C# for the .NET platform, available under the Mozilla Public License, and maintained and updated by a team of volunteers. MapWindow is available in version 4. In 2015, a complete rewrite of the software was started that is currently available as MapWindow5 version 5.2.0.
OpenJump
OpenJump, originally called Jump GIS and designed by Vivid Solutions, is another Java based open source GIS software developed by a team of volunteers. Like most other GIS systems, it provides an interface for creating plugins to extend its functionality. The latest release, version 2.2.1, is from the May 2023. OpenJump is published under GNU GPL license.
SPRING
SPRING is a freeware GIS and one of the older GIS systems available. It is developed by the Brazilian National Institute for Space Research (INPE) since 1992. In particular, it provides advanced remote sensing data and image processing capabilities. SPRING requires you to register before being able to acquire the software and has a special license specifying how it can be used.
uDig
uDig is a Java-based GIS system that is embedded into the Eclipse platform. It is developed by Refractions Research and published under Eclipse Public License EPL. Currently, the newest available version is the release candidate for version 2.2.
QGIS
Lastly, we come to QGIS, the open source software that this lesson will mainly be about. Development of QGIS was started in 2002 by Gary Sherman under the name Quantum GIS. QGIS publishes updates in short intervals and a new milestone has been reached with the release of version 3.0 in February 2018. QGIS is by many considered to be the leading open-source desktop GIS software due to the broad range of functionality it provides, its easy-to-use and flexible interface, and the very active community. QGIS has been written in C++ and Python. It provides an interface for extending its capabilities via plugins written in Python that we will work with later on in this lesson. QGIS is developed by a team of volunteers and organizations, and supported by the Open Source Geospatial Foundation umbrella organization for open source GIS software. It is published under GNU GPL license.
From a programming perspective, the focus of this lesson will be on object-oriented programming in Python with the goal of gaining a better understanding of some concepts like objects and classes that we have already been using quite a lot in Geog485 and in the first lessons of this course. But now we will study this topic in more depth and you will learn how to write your own classes and use them effectively in your own programming projects to produce better-structured code that is also more readable and easier to maintain. You will apply what you learned theoretically in this lesson to write plugins for QGIS to extend its capabilities. Implementing these plugins will also include further GUI designing work with QT as a continuation of what you learned in lesson 2. However, before we further talk about object-oriented programming, we provide a brief overview on QGIS in the next section.