@katto: I have always had problems getting the .dxf export from Serif Drawplus to work in City Engine (which likes the AI export). In the end I have to open the .dxf file in Campaign Cartographer 2 (which is built around Autocad I think) which then allows me to export it in a way that City Engine likes. It was a while back when I did this and really fiddly, but give me a couple of hours or so and I should be able to figure out how to do it again.

The hours I spent trying to get CE to accept a Serif Drawplus .dxf and the zillions of different freeware programmes I downloaded to try and get it done .. it was a lot.

I'll give it a try...hang on.

There is a free starter version of Drawplus here: http://www.serif.com/free-graphic-design-software/

but I don't know if it will open .svg files....worth a try!