Making a Simple Figure-Ground Map with OSM Data and QGIS.
Last week I a published a series of figure-ground maps looking at the urban structure of different cities. My maps were inspired by Alasdair Rae’s series of 10x10km maps of UK towns and cities. This article will briefly describe the method I used to generate these maps. I am sure that there are many other methods (possibly easier), but this is the one I used. For this tutorial, you will need some basic experience using QGIS and Adobe Illustrator.
Firstly, we need to get our data. I used OSM building data from https://osmbuildings.org. On the website simply click on Data and then Free Data until you get to the following page.
Simply search for the city or town you are interested in and click run. Some cities have rich data while others unfortunately do not have enough data to generate a figure ground map. When you find your desired area click on “Run” in the top left. Some larger areas may take a while to load so be patient until your data loads. You may get a warning if you selected a large area so do not worry. When the data loads click on “Export”. Download the data as a GeoJSON.
After the data downloads, open up QGIS and click on “new empty project”. Click and drag your data on the blank space select “Polygons” to load. You should see the buildings load in to form a rudimentary version of of the final map.
If your chosen area contains a body of water and you want to include it, you will need to find an appropriate shape/vector (GeoJSON, Shp) layer to go under the buildings. A quick Google search for a city’s administrative region file often yields the desired file. It is recommended to add a scale bar to help know what scale you are working on. This can be used later in Illustrator for scaling and can be removed if desired.
At this stage, we need to export the image as a pdf (which maintains the vector data) so that we can add the final touches in Adobe Illustrator (or your preferred vector manipulation software. To do this click on project > Import/Export > Export Map to PDF.
Choose your desired scale and save the map to your desired location.
Open the saved PDF in Adobe Illustrator. Select one of the buildings then under the select menu choose same appearance so that all buildings are selected. Choose the desired outline (stroke) and fill properties (I choose no outline with a black fill).
For the water body, the instructions will depend on the type of file. If you have the water shape, simply select it and choose a blue colour. If you have a the land shape, make sure it is white (or another colour of your choice) and add a new layer in behind it and make it blue as seen in the image below.
And that's it! Export it to your required proportions. You can do this by changing the size of the art-board or cropping it after exporting. You may use the scale we added in QGIS to make sure the final map is correctly scaled.
