Virtual Urbanity is a thesis project that was designed by Rafail Bakolas at the Bartlett School of Graduate Studies. It was programmed using the processing language. It is a parametric simulation engine which models a vast and diverse amount of 3D urban configurations. It is based on a Lindenmayer system which I think works like fractals. Or even like Processing on some level. So there would be a set of rules (if this, then that) which take a string of input and produces an output that grows exponentially. This project defines the topology, the geometry, the width, the length, the density and the spatial significance of the streets. Conceptually the aim is to draw relationships between the creation of a realistic urban setting in the physical world to the abstract imaginary environment of the virtual world.
Here is where you can get a pdf of the thesis. It’s pretty interesting stuff.