By David Crowther
In a previous blog we reviewed a number of Routing and Distance calculation tools available within QGIS:
QGIS – Routing and Distance Tools
In this new blog we will explore another routing tool which enables you to create drivetime and pedestrian catchment zones allowing you to spatially analyse your assets or customers. The tool is available as a free plugin for QGIS, but requires an API Key to utilise online routing algorithms using either a free to use or pro version (monthly price plan).
Follow these steps below if you wish to trial the plugin and within a few minutes you will be generating isochrone catchment boundaries within QGIS!
Firstly, use the Plugins Manager to search for and install the Location Lab: Catchments tool.
Once successfully installed the tool will be added as an extra menu named Location Lab in QGIS.
Choose the Catchments sub menu and the tool is then auto added as a PANEL in QGIS.
In order to use the Location Lab Catchment generator you will need to register for an API key from one of the online resources, either SKOBBLER or HERE
At the time of writing this blog (May 2019), the SKOBBLER website and SDK was undergoing updates so new registrations were not being accepted. Therefore this blog concentrates on the HERE resources.
To get an API KEY choose the API Provider e.g. HERE and then press the Get Key button.
A webpage will open allowing you to register for a FREE HERE account.
https://developer.here.com/?create=Freemium-Basic&keepState=true&step=terms
The free pricing plan provides the following monthly transactions.
Having created a FREE account, sign in and choose to view your PROJECTS.
Select your Project and the Credentials for your account will be shown. In order to use the Location Lab: Catchments tool you will need to Generate a JavaScript/REST App ID and App Code.
Once the App ID and App Code have been generated COPY and PASTE them, with a COLON separating them, into the KEY field in the Location Lab QGIS tool.
In order to generate a catchment isochrone we will need some point data open in QGIS, allowing us to choose a location or set of locations to generate the isochrones from. In the first example we will open the School locations in the UK and add OpenStreetMap as a basemap.
To generate an isochrone catchment from a school select the chosen school in the map (it will turn yellow) and from the Location Lab tool set the Select Point Layer to be Schools and tick the Only Selected (1) option.
The Mode section allows you to define the Mode of transport e.g. Car, Pedestrian or Truck.
If we choose CAR or Truck we can also choose to utilise Traffic information, but for the Freemium HERE API we don’t get the option to avoid Tolls or Highways.
In addition, the Mode section allows you to define the value for the journey and whether the value is in Time (Minutes) or Distance (Meters).
Having selected one school as the starting point and set the parameters for the isochrone, press the Get Catchments button to create the catchment area. The isochrone is generated and added to the map as a new polygon layer where you can edit the style settings to make the layer transparent.
Using the QGIS Select by Location Tool, you can now use the Isochrone catchment polygon to select features that are within or outside of the drivetime.
The School points within the drivetime polygon are now selected (in yellow) and can be viewed in the Attribute window, as well as exported to XLS or exported to create a new GIS layer.
This time by choosing 5 School points in the map and a 60 minute drivetime, we can generate 5 Isochrone catchment boundaries of one hour time from each of the 5 chosen schools. This therefore allows us to undertake spatial analysis on multiple features, for example this could be useful when analysing what assets to close or to identify the most suitable site for a new school.
Using the Pedestrian Mode, we can also undertake more localised analysis, for example generating 60 minute walking catchments around our Service Points to ensure that all houses in the local authority have easy access to council services. Where there are gaps in the catchment coverage areas we may need to look at placing new Service locations or possibly mobile services.
At an even more local level we can use the Pedestrian mode to generate a catchment isochrone around an individual school to identify school catchment areas or to calculate which pupils qualify for school travel awards.
Generating catchment isochrones is a great way to generate time and distance polygons in order to spatially analyse your assets or to better understand your local community.