from the How it works dept.
In this GameDev.net article, a Teppo Soininen of Umbra discuss their occlusion system, a real-time method of optimizing frame rates in rendering engines – basically, visual middleware.
TS: Basically, this is our middleware solution, which is using Big World’s engine to do rendering. What’s happening over here, here you can see the player’s eye view, and on the right-side you can see the bird’s eye view of the whole scene. You see only the visible geometry, a couple of houses. Now, I switch umbra, our middleware solution, off, and you can see the whole city. A real big city. This has more than a hundred thousand objects around, and it would ridiculously slow the rendering without any occlusion culling or visibility optimization. If we turn umbra on, and you can see it only renders the houses that are visible. I can move around, it updates. All the updating is done on the fly. We’re not doing any preprocessing of the scene, or anything like that.
There is also a great showreel here of the Umbra occlusion system working inside BigWorld.