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Thread: size of normalization cube map

  1. #1
    Senior Member Regular Contributor
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    size of normalization cube map

    I've got tangent space bumpmapping working, thanks primarily to Paul's excellent tutorial, as well as numerous other tutorials and examples.
    http://www.paulsprojects.net/tutoria...implebump.html

    I've got a question about the normalization cubemap. Most examples I've seen use a cube map with dimensions of 32. I've used Mark Kilgards "A Practical and Robust Bump-mapping Technique for Today’s GPUs" document to create the normalization cube map, and have experimented with various sizes of cube maps.

    I've seen that when values below 32 (16 and are used, artifacts are visible on the surface, however no discernable visual difference is apparent with cubemap sizes above 32 (64 and 12. So I'm guessing that the examples I've seen use 32 for the size, as that consumes the minimal texture memory with good visual results.

    Is that about right, or am I missing some critical detail?


    [This message has been edited by yakuza (edited 02-29-2004).]

  2. #2
    Senior Member OpenGL Pro
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    Re: size of normalization cube map

    I am not sure the beginners forum is a good place for stuff like this.

    Mikael

  3. #3
    Senior Member OpenGL Guru
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    Re: size of normalization cube map

    nVidia has just recently put up a new paper on their site ( developer.nvidia.com ), which talks about normalization.

    THEY use a cubemap sized 256*256. And still they say, that it gives some artifacts in certain situations.

    Using 32*32 sounds to me VERY bad, the changes between two normals should be quite big.

    Certainly there are a lot of cases where you won´t notice the low resolution, especially on very bumpy surfaces. Try out a completely flat surface and make screenshots of it using different cubemap resolutions. Then compare them. It should help you to decide, which is the best resolution.

    Jan.

    PS: When using Specular Lighting, it should get much more noticable.
    GLIM - Immediate Mode Emulation for GL3

  4. #4
    Super Moderator OpenGL Guru imported_dorbie's Avatar
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    Re: size of normalization cube map

    Moving to the advanced forum.

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