I came across a interesting post in the "DirectX Developer Forum" (see below) which might explain the subtle IQ issues with Nvidia hardware in the 3D Mark 03 'Mother Nature' test. In short, Nvidia drivers may be converting a high resolution normal map to a paletted version.
"Re: ATI Radeon 9700 doesn't support D3DFMT_P8?
The trouble with using a palette for a normal map is that it doesn't generally maintain good quality. With only 256 absolute normals represented (plus interpolations between pairs) you tend to get quantization artifacts rather sooner than most people expect.
So much so that one very important software developer that I'm working with (who I cannot name right now) has decided not to accept paletted maps for normals. And because they're worried that some IHV's might conceivably try to change the data behind their backs (to trade speed for quality) they're planning to release a white paper at the same time as their software stating that drivers which _do_ cheat by using paletted textures are going against their express wishes and should not do so. [It'll become obvious why this is could become an issue at some later date.]
It'll be interesting to see how it all works out..."
"Re: ATI Radeon 9700 doesn't support D3DFMT_P8?
The trouble with using a palette for a normal map is that it doesn't generally maintain good quality. With only 256 absolute normals represented (plus interpolations between pairs) you tend to get quantization artifacts rather sooner than most people expect.
So much so that one very important software developer that I'm working with (who I cannot name right now) has decided not to accept paletted maps for normals. And because they're worried that some IHV's might conceivably try to change the data behind their backs (to trade speed for quality) they're planning to release a white paper at the same time as their software stating that drivers which _do_ cheat by using paletted textures are going against their express wishes and should not do so. [It'll become obvious why this is could become an issue at some later date.]
It'll be interesting to see how it all works out..."
