If an object is only drawn far away, do its textures just take up video memory for the necessary mip levels, or the highest resolutions? In particular Oblivion has separate meshes for distant buildings, and I'm wondering if it would save video memory if they used lower resolution textures.
I've found various information online, but no answers: Virtual video memory should make it easy to let high mip levels page out. OpenGL and DirectX both have functions to say you only want rendering to use lower-resolution levels in the mip map, which kind of implies it might actually help on some hardware (especially as the OpenGL docs talk about using it while you load the high resolution data). This MegaTexture stuff sounds basically like manually managing what mip maps to load yourself so you can fit just the necessary filterings of huge textures on the video card, which sounds like the hardware doesn't handle this stuff really well.
I've found various information online, but no answers: Virtual video memory should make it easy to let high mip levels page out. OpenGL and DirectX both have functions to say you only want rendering to use lower-resolution levels in the mip map, which kind of implies it might actually help on some hardware (especially as the OpenGL docs talk about using it while you load the high resolution data). This MegaTexture stuff sounds basically like manually managing what mip maps to load yourself so you can fit just the necessary filterings of huge textures on the video card, which sounds like the hardware doesn't handle this stuff really well.