THING 18 – Geospatial data 2019-04-11T14:40:06+00:00

Project Description

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!

ACTIVITIES

In this activity, we will add data to a collaborative mapping venture. OpenStreetMap is a crowdsourcing mapping project that aims at providing free and open geospatial data for all kinds of applications ranging from Craigslist to FourSquare.

First, go to https://www.openstreetmap.org and create an account. Then, choose one of the two following activities. Activity 1 (describing existing features using “Points”) is pretty straightforward. Activity 2 (creating a new feature) is slightly longer and involves a bit more exploring in OpenStreetMap.

Activity 1: Describing existing features using “Points”

  • Click on Edit (make sure to use iD, the in-browser editor). You will then enter the editing mode based on satellite imagery. Now add a few Points describing either a business, a public building or natural feature.
  • First, click on the Point button (top left) and choose a location on the map with the mouse.
  • Then, by selecting one of the feature types (Natural features, Park, Hospital, etc.) from the menu on the left (you can also search for types e.g. bicycle rental), a form will appear with information fields. Add as much information as you have, and repeat for as many locations as you like!

Activity 2: Creating a new feature in OpenStreetMap

In OpenStreetMap, you can draw polygons and lines to identify the boundaries of features such as buildings, roads and parks.

  • Ideally, choose an area outside of a large city as buildings’ boundaries in large cities have been largely identified already.
  • Then click on the Area button and, using the satellite imagery as a guide, draw the boundaries of building (a house, a store or any other building). Finally, choose feature type on the left hand side menu and add as much information as you have.
  • Add a description of the change you made under Changeset description and click on Upload to complete your addition to OpenStreetMap.

NOTE: Make sure to save your changes when you are finished. It may take a few hours before the changes are reflected in the public-facing OpenStreetMap display.

More information:

Here is a short, introductory YouTube video on spatial data by the University of West Florida.