Combining data in CityEngine is really easy, take this example I’m working on at the moment:

I’ve taken an old georeferenced map of London and I placed real world current 3D urban data from the nice people at CyberCity3D. I’ve digitized one of the old barracks shown on the old map actually within CityEngine and run one of my generic office block rule files over it. I’ve also run a floor level split rule over some of the CyberCity3D data (in the bright green) this has much more potential than just colouring or texturing buildings and I’ll be looking at this in detail soon…
For landscaping I’ve used a palm grove rule file, obviously I need to model new trees for this model!

This is obviously experimenting with different types of data and different sources of data, I’m toying with the idea of doing a before and after 3D model of this area of London. Then I might use some futuristic models to have some fun with it!
For those interested I used an extract of Greenwoods Map of London 1827 and data given to me by these guys at CyberCity3D.
Thanks goes to my wife @MMhartley who has an amazing online historic links resource…