THING 18 – GEOSPATIAL DATA
You may think that you have no idea what geospatial data is, but did you know that you are using it every day? Did you ever wonder how the photos you take with your phone come with a location tag? Have you ever used Google Maps or Bing to find your way around town or on a road trip? Then you are familiar with some of the multiple uses of that type of data. Here is another fun example:
Geospatial data, sometimes referred to simply as spatial data, is any type of data or object that has geographic coordinates (latitude and longitude for instance). If a dataset can be mapped to the surface of the earth, it constitutes geospatial data. Thus, geospatial data is used to locate and describe geographic features and the relations between them.
Some of the most common types include topographic data (data used to produce topographic maps that provide detailed descriptions of natural and man-made features including elevation, water bodies, vegetation, buildings, roads, infrastructures, etc.); othophotos (aerial photographs that have geographic coordinates and reflect real distances on the ground); LiDAR data (precise elevation data collected using an aerial laser); cadastral data and road networks.
A common way of creating a geospatial dataset is to start with an image (an aerial photo, or the scan of a physical map for instance) and to add geographic coordinates to it by using reference points that can be precisely located on the surface of the earth. This is called georeferencing. In a similar way, you can start with a dataset describing a set of locations, via their addresses or postal codes for instance, and add specific geographic coordinates to those locations. This is known as geocoding.
Geospatial data is usually analysed and treated in sophisticated software known as geographic information systems or GIS for short. Some of the best-known systems are ArcGIS, MapInfo and QuantumGIS (QGIS), which is an open source and free software. Additionally, several online tools that are easy to learn and nearly free allow users to create maps based on their own data, or by using existing datasets. Some of these tools also have georeferencing and geocoding features. Here is a short list of online mapping tools: Carto, BatchGeo, MangoMap, Mapbox and OpenHeatMap. Each of these has different features, explore them and create your own maps!