Understanding GIS

Before jumping into the installation process, let's discuss geographic information systems (GIS) a little bit. GIS is a system for collecting, manipulating, managing, visualizing, analyzing, and publishing spatial data. Although these functionalities can be bundled in a single software, by definition, GIS is not a software, it is rather a set of functionalities. It can help you to make better decisions, and to get more in-depth results from data based on their spatial relationships.

The most important part of the former definition is spatial data. GIS handles data based on their locations in a coordinate reference system. This means, despite GIS mainly being used for handling and processing geographical data (data that can be mapped to the surface of Earth), it can be used for anything with dimensions. For example, a fictional land like Middle-Earth, the Milky Way, the surface of Mars, the human body, or a single atom. The possibilities are endless; however, for most of them, there are specialized tools that are more feasible to use.

The functionalities of a GIS outline the required capabilities of a GIS expert. Experts need to be able to collect data either by surveying, accessing an other's measurements, or digitizing paper maps, just to mention a few methods. Collecting data is only the first step. Experts need to know how to manage this data. This functionality assumes knowledge not only in spatial data formats but also in database management. Some of the data just cannot fit into a single file. There can be various reasons behind this; for example, the data size or the need for more sophisticated reading and writing operations. Experts also need to visualize, manipulate, and analyze this data. This is the part where GIS clients come in, as they have the capabilities to render, edit, and process datasets. Finally, experts need to be able to create visualizations from the results in order to show them, verify decisions, or just help people interpreting spatial patterns. This phase was traditionally done via paper maps and digital maps, but nowadays, web mapping is also a very popular means of publishing data.

From these capabilities, we will learn how to access data from freely available data sources, store and manage them in a database, visualize and analyze them with a GIS client, and publish them on the Web.