Isn't occlusion somewhat seperated from culling using octrees and bsp's?
One could use an occlusion step afer getting the potentially visiable set from the octree or bsp. then It would figure out what needs to be drawn and what is behind something else and therefore doesn't need to be drawn.
A good general purpose occlusion system would allow you throw abritray geometry at it and it would only draw what was visible. I know it sounds like the holy grail but such systems exist.
One could use an occlusion step afer getting the potentially visiable set from the octree or bsp. then It would figure out what needs to be drawn and what is behind something else and therefore doesn't need to be drawn.
A good general purpose occlusion system would allow you throw abritray geometry at it and it would only draw what was visible. I know it sounds like the holy grail but such systems exist.