In GIS, the most common way to get a feeling about a data set and to assess its quality is visual inspection. Artefacts or plausibility errors are easy to detect this way.
In 3d, things also look nice. We’d like to show you how to achieve this in QGIS. QGIS is the most frequently used open source and free desktop GIS solution and it’s well suited for this kind of work. It can read many vector and raster formats and provide a 3d map view from different sources. For a nice looking visualisation, follow these steps:
- If you don’t have QGIS on your computer, download and install the software from: https://qgis.org/
- Download data: https://map.onegeo.co/ (a small region is free if you sign up for a coupon)
- Unzip the data if necessary and drag the json file into QGIS
- It is important to change the project’s coordinate system to an UTM projection. Depending on the location of your input data you can find the right UTM zone and the corresponding EPSG code here: https://epsg.io/
In case of Philadelphia it is EPSG:32618. Click on Project in the main QGIS window and choose Properties. In the newly opened window choose CRS and enter your EPSG code(Philly EPSG:32618) in the Filter field. Choose your UTM zone (Philly: WGS84 / UTM Zone 18) from the coordinate reference systems list and click Apply. Close the window.
- For verification, please check if you see EPSG 32618 in the status bar at the bottom. If it is still EPSG 4326, the next steps will not work.
- Now open Layer Properties . Do so by right-clicking on the newly added layer (in the list left hand side) and choose Properties. In the open window select 3D View and choose the Single Symbol option.
- You now have a number of options to choose from. The most important is Extrusion. If you change the number in the corresponding field, all buildings will have the same height. If we want to see each building’s individual height, we need to tell QGIS to check the height property for each building and use this as an extrusion. We can do this by clicking on the symbol behind the Extrusion number and choosing field type height. Click on Apply in the bottom of the window and close it.
- Now QGIS knows where to check for the height of the buildings. Next step is to choose View in the QGIS main window and click on new 3D Map view. A new window opens with a 3D map view of the underlying data which should look similar to the one below.
This is an easy way to set up a proper view of geospatial data in Open Source Software. It is also possible to add a WMS background layer to visualize a satellite image background.
For more tips and tricks, don’t forget to follow us on Medium, and to visit us on the web at: https://onegeo.co/
Thanks for reading!
Update 2023–01-11 Links updated for ONEGEO, sample data replaced by info about user defined selections.