what is the common practice to filter and generate mip chain for normal maps?

Discussion in 'Rendering Technology and APIs' started by shuipi, May 11, 2010.

  1. shuipi

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    Everyone knows normal map. But when I actually went to ask whether you can filter (average) directions, and what is the common way of doing it in most modern games, few could answer for sure. It seems to me that it's fine to use anisotropic for min filter and linear for mag filter, and generate mip chain just like color textures. But I want to make sure
     
  2. Andrew Lauritzen

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    They don't filter properly with mipmaps... most people just enable it anyways and ugly and obvious blurring and clear mip transitions result.

    Instead I highly recommend looking into LEAN Mapping for high quality results. This is "proper" normal map filtering and the results are well worth the cost on modern GPUs.
     
  3. shuipi

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    if just let the hardware do the filtering, it will be linear filter, and the lerped normal won't be normalized anymore right? Most games just ignores this?
     
  4. Andrew Lauritzen

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    Yeah it's very wrong even if you renormalize and it'll cause specular aliasing and "blurring out" of normal map details. Games typically have ignored this but honestly I think the LEAN mapping paper (just came out this year) will hopefully change that since it's the first reasonable and efficient way to do it properly that I've seen.
     
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