I'm somewhat confused on how octrees are used to check the frustum intersection with the 3d world. In OpenGL all transformations are performed on world 3d objects, while the frustum remains unchanged (along the Z axis) - at least that's my understanding. Now when using octree do you have to 1) rotate the octree cubes with the world (to maintain the 3d object <> octree node relationship) and then perform the octree/frustum intersection test ? It seems like you have to write your own rotation routines to do that since you can't simply send those to OpenGL because they will be rendered immediately. Or do you rotate the frustum (on your own), perform the intersection test, then send the detected cubes (3d objects in those cubes) to the rendering pipe ?
I would appreciate if someone could clarify this issue for me.

Martin