Epic's Unreal Engine is one of the most popular and successful Game Engines out there. Epic recently released the Unreal Development Kit (UDK), an easy-to-use integrated graphic environment for authoring games or interactive architectural content, capable of creating standalone applications/games. A good reason to test the workflow between CityEngine and UDK.

Features:

• Instanced asset export from CityEngine to UDK via Unreal's t3d format using the Python-based exporter.
• Modified CityEngine scenes can quickly be imported into UDK which allows to iteratively design and test different versions of the city layout.
• Beside instanced geometry, additional Unreal-specific metadata such as collision or lighting attributes can be defined arbitrarily and are generated and exported per asset instance in the same step.

The video below shows a city generated with CityEngine in the Unreal Game Engine.

A possible production pipeline from CityEngine to UDK could consist of the following steps (as shown in the video):

1. Prepare your own set of textured building assets and street elements
2. In CityEngine, generate a city scene using these assets
3. Define report variables to your CGA file that store necessary information such as asset ID, position, scale and rotation
4. Define additional render-specific attributes such as shadow, collision or light parameters
5. Prepare an exporter Python script that generates a t3d file reading the reported values.
6. Export from CityEngine with the python export script enabled
7. In the Content Browser  of the Unreal Editor, prepare static meshes from the building assets (ActorX export (.ase files) from Max/Maya or Collada from CityEngine).
8. In Unreal Editor, import the generated t3d file into your scene.

• Thanks to lubitel for help with UDK, contributions and preparing the exe.
• Building assets provided by CASCADE ANIMATION

The video below demonstrates the workflow: