nVidia Acknowledges MIP-Mapping Concerns

Recently, some users on the Net have complained about apparent texture compression that occurs in some Direct3D games using 3D accelerators based on nVidia's RIVA 128 chip.

Products using the RIVA 128 include the STB Velocity 128, Diamond Viper 330, ASUS 3Dexplorer, and others.

What underlies some of the problems is the RIVA 128's ability to create MIP maps where there are none. MIP-mapping is a technique in which multiple textures represent differing levels of details at different distances. You might have a very low resolution texture map on an object that is at a long distance, a somewhat higher map at medium distance, and the best quality texture when you're nose up against the object.

Not all Direct3D games use MIP-mapping. In those cases, the RIVA 128 creates low resolution textures from an existing texture at two different detail levels, then uses those down-sampled textures as MIP maps on objects that are in the distance. Up close, the normal texture is used. This reduces the bandwidth required to keep bringing in the higher resolution textures.

Michael Hara at nVidia stressed that, should a Direct3D title use MIP-mapping, the RIVA 128 doesn't touch any of the textures. It's only in titles that do no MIP-mapping of their own that the RIVA uses its internal MIP map-generation algorithms.

Earlier RIVA 128 drivers often demonstrated texture "flashing" (different MIP maps flickering in and out), but recent driver releases have fixed the problem. The RIVA 128 remains one of the fastest, consumer-level 2D/3D accelerators on the market today.