[levesque]

For what I know that's still a challenge for developers, they most often seem to make two distinct types of area:

-Outdoors, where there are no concavities in the landscape and elevation models are used.

-And indoors, where you use a different type of modeling, last time I checked binary space trees were pretty common.

[jheriko]

fyi the reason for using a BSP is to get a "cell-portal graph" which allows visibility computations to be trivialised - the benefits of the BSP tree itself for, e.g. rendering with no overdraw are not very valuable. e.g. despite the hype otherwise this was never realised in Quake for zero-overdraw rendering, instead the PVS (based on the cell-portal graph) was used to result in "very little overdraw". This technique continues to be used today in every major game engine (id Tech 4 (maybe 5?), Source, UE3, CryEngine, numerous other proprietary engines).