What is GIS?

What is GIS

Geographical Information Systems (GIS) are a type of computer software that is designed to handle special types of data that contain information about geographic features. These types of data are called geospatial data.

GIS is around us in everyday life, it is present in car satellite navigation systems, it aids location services such as the emergency services and it allows insurance companies to assess flood risk to properties.

GIS is not a single software program, it is a term used to describe a range of types of software that can handle spatial data and carry out particular tasks to visualise and analyse spatial data.

Some GIS software can be quite complicated to use, but there is a wide range of desktop and online programs available now that are easy to get to grips with, do not require specialist knowledge and are ideal for teaching geographical concepts and enquiry skills.

Geospatial Data - Representing real world features

Geospatial data that GIS software uses are digital datasets that represent real world geographic features such as roads, rivers, buildings and trees. Geospatial data can also represent the terrain and height of the land, administrative boundaries and aerial images of the Earth’s surface.

Vector and raster data types

Geospatial datasets can be broken down into two types of data, vector and raster.

Vector data is generally used for representing point, linear and area features.

  • Point features could be the location of individual trees, survey sample sites along a river, the location of a person’s house
  • Linear features could be rivers, roads, railways and paths
  • Area features could be lakes/lochs, fields and buildings.

Vector features comprise a set of coordinates (or many to create a line or area) and associated attributes that tell us something about that feature, e.g. tree species or land use type.

Raster data are made up of a continuous grid of cells each with a numeric value. Each value represents something particular and together the values build up a digital version of a feature. For example, terrain data is commonly raster data, where the value represents the elevation of that cell. Other common types of raster datasets are backdrop maps and aerial images.

GIS software can handle vector and raster data together in one place and enable you to view and interrogate multiple different dataset in order to find out something about your area of interest.

The maps available from MapStream for Schools are all raster datasets. This means that each cell in the datasets represents a colour that any GIS can read and interpret to display maps images.

Thematic approach of GIS

The most common way that GIS software handles and organises spatial datasets is using a thematic approach. In this case, each dataset contains similar information e.g. rivers, roads, building that can be overlaid on top of each in the GIS. Layering up these datasets enables us to query and learn something about our area of interest.

Benefits of GIS

GIS software and geospatial data enable users to interrogate data to analyse and draw conclusions. From simple interpretation of maps created to more complex spatial analysis, GIS enables a vast range of tasks. GIS is primarily a tool to aid decision making being used to help answer common questions such as ‘where can a new wind farm be sited?’, ‘which species of plants occur along a transect?’. The power of GIS is in enabling users to combine a range of data required answering these questions easily, to analyse and draw conclusions.

Introduction to GIS software

GIS software can broadly be divided into four categories:

  • Desktop: installed on stand-alone computers
  • Web: accessed online, no software installs required
  • Mobile: apps for smartphones to view and collect data
  • Server: advanced software for distributing and processing data

GIS software enables users to view, explore, create, edit, store, query and analyse spatial data. The most relevant types of GIS software for schools are Desktop and Web, but Mobile app usage is increasing as the technology becomes more accessible to schools.

GIS Software can be further broken down into Proprietary (commercial) and Open Source (free) software. The most commonly used proprietary desktop GIS is ESRI’s ArcGIS. Other notable proprietary desktop GIS include MapInfo and AutoCAD.

Open Source GIS is an area of development that has grown significantly in recent years resulting in powerful, robust and well supported software. Most importantly, these programs are free. That means no licence or maintenance costs and no restriction to how many computers have software installed on them. There is a wealth of open source programs available that have different strengths, however Quantum GIS (QGIS) has become an excellent all-rounder and is proving to be popular and robust enough to be used by Local Authorities, commercial companies, consultancies and many others.

Other key open source desktop GIS include GRASS GIS, gvSIG, MapWindow and uDig.

Web GIS is another area of GIS software that can be very useful for schools. The most common and popular web GIS is Google Earth. Some may argue that as it does not have the full analytical and data processing tools that a traditional desktop GIS has, that Google Earth is not a GIS, but in terms of a program that can handle spatial data to enables users to view and interpret the data, then it is a GIS.