Before CityGen3D can create a scene, you need to specify a location.
You can select your chosen area via a scrollable and zoomable 2D map of the world, or enter the latitude and longitude manually.
Map information for the selected location is then downloaded from OpenStreetMap in XML format.
CityGen3D will be able to identify various common map features from this XML, such as roads, buildings, forests and beaches.
Once the data is parsed, it is saved as a database asset so you don't have to process it again unless you want to make changes.
It is also possible to customize the data processing system in order to identify rarer features that may exist in your data set, or treat existing ones as something else.
So CityGen3D gives you complete control over how the raw OSM data is interpreted by Unity.
An interactive 2D map allows you to examine your downloaded data in more detail, before you proceed to 3D scene generation.