The planning and management of a given environment is often heavily dependent on an understanding of the spatial arrangement of things and properties within the environment. We often need to answer questions relating to key spatial properties such as:

• Location: Where are there sufficient wind resources for a wind farm, and what is already at that location?
• Patten: Where in Copenhagen do we find the highest concentration of students
• Flow/connection: What is the fastest/cheapest route from A to B, and how much traffic would a given project generate along a specific route?
• Spatial Relations: What is the distance to the nearest green area, and how many green areas can you access within 10 minutes of walking?
• Local appearance: How will the erection of a new building influence the appearance of a town square?

These kinds of questions lead to the need for a system that can collect, manage, analyse, and communicate information about the spatial arrangement of things and properties, and this is exactly what geospatial technologies can deliver. A system that combines different geospatial technologies and geospatial data to solve a specific task is generally named a Geographic Information System (GIS).  Defining exactly what is and what isn’t a geospatial technology is not easy and probably not even useful. In this compendium, we will apply a rather wide definition of geospatial and include all technologies that allow us to collect, manage, analyse, and communicate information about the spatial arrangement. This includes the use of geospatial data in different environments such as spreadsheets and game engines.

Unfortunately, there is quite some naming confusion in relation to GIS. Originally the term GIS refer to “A system that combines different geospatial technologies and geospatial data to solve a specific task”  including any organisational setup surrounding such a system. As GIS became more, proliferate it became common to use the terms GIS to describe a single application or suite of applications used to collect, manage, analyse, and communicate geospatial information.  Today we have product names like QGIS and ArcGIS that reflect this trend.  I will follow this trend and use GIS in both meanings however if the right meaning cannot be seen from the context I will use the term Geographic Information System Application (GISapp) when talking about applications and Geographic Information System (GISys) when talking about a system.

In Anglo-Saxon academia, the term Geographic Information Science also abbreviated GIS, or sometimes GIScience became common in the 1990’ties. GIScience describes the academic discipline of using and developing algorithms for Geographic Information Systems, in this GIScience can be seen as a synonym for what in the Germanic languages is called Geoinformatics although Geoinformatics typically has a little more emphasis on the organisational context and social/political implications of the use of GIS.

In modern society, space has become a scarce commodity, and the need to careful manage and plan has become ever more obvious. Space has literally and figuratively become a battlefield between competing interests, and the use of GIS has become an essential tool in this battle. For planners/managers GIS is the key tool to cope with the increasing complexity of the human environment and the need to make informed decisions about the use and development of land. GIS allows planners to analyze and visualize data related to land use, transportation, pollution, demographics, and other factors that affect the development of a given area. One common task performed using GIS is to identify and prioritize suitable locations for certain activities based on the specific needs of those activities and at the same time ensure that the use aligns with existing rules and regulations. In parallel with this GIS also allows planners to create maps, 3D models and even immersive Virtual Reality experiences that can be used to communicate ideas and plans to stakeholders and the general public in a way that is easy to understand and engage with. This is especially important in relation to communicative or participatory planning, where the goal is to involve stakeholders and the general public in the planning process and to ensure that their concerns and needs are taken into account.

What makes GIS so useful and where to look out for traps?

What really makes GIS a powerful tool in mode society is its ability to combine and reuse existing data in new combinations to solve problems the data was not originally designed to solve. At the same time, this is also the Achilles heel of GIS, do we tend only to consider the aspects of a problem we have data for and can data really be used to solve problems it was not intended for? Before diving into the use of GIS, it is therefore worthwhile investing some time in understanding how a model of reality is represented as geospatial data, for this is the first and perhaps most important thing to remember when using GIS, geospatial data is not a representation of reality, it is a representation of a model of a selected aspect of reality.

Esbern Holmes