Then there are the standalone tool pipeline processors, namely the lighting and visibility tools, both developed by Jan. The lighting tool is a raytracing lightmapper, which stores the light colour and direction for every point in the game world. Light is cast from the sun and the sky dome, then bounced around within the city giving an amazingly realistic result. Even dynamic objects are lit using this information, so they sit convincingly in the game.
The visibility processor allows us to calculate what objects are visible from a given location in the world, which means the game doesn't have to render everything all the time. As both the lighting and visibility tools are processor intensive they are designed to split the load across the office LAN, so each PC runs a screensaver which processes tasks as needed whenever the machine is idle. Think Seti@Home, but with fewer graphs.