Do you know of any terrain formats for FPS games that use a triangulated irregular network (TIN) instead of a grid for elevation representation? Or at least a game whose development tools accept a TIN as input for terrain elevation?
The only example I have is the ASCII Scene Export (ASE) format that can be used as input in the terrain editor for the Unreal engine (UnrealEd). I am mainly looking for formats that support terrain holes (both visually and in collision detection) and allow underground models. I want to avoid having to carve and cover gridded terrain elevation grids to place underground models.