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Normal map issue, Maya

Spur
Spur
polycounter lvl 6
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Spur polycounter lvl 6
Hi guys. I'm having a problem baking a normal map in Maya and need some feedback. The bolts on my bearing caps keep coming out skewed. Is there anything I can do to correct this?

Normals.jpg
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  • bugo
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    bugo polycounter lvl 17
    there's 2 ways, or you do a smooth group at the last circle on your mesh or you customize your vertex normals so it can bake in a way it doesnt distort on the cap of the cylinder. Also make sure you are modeling the bevels of your high model in a way normal map can get it! In your image I can see you didn't do it.
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  • vahl
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    vahl polycounter lvl 18
    the best way would be to simply add supporting geometry, add an edge loop on the border of your cylinder cap and the skewing will be fixed, also take bugo's advice on the bolts
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  • Spur
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    Spur polycounter lvl 6
    Thanks for the reply guys. You mentioned my bevels needed to be modeled in a way the normal map can pick it up. So I need to add more divisions to my bevel? I'll give the supporting geo suggestion a try!
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  • Spur
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    Spur polycounter lvl 6
    Ok I've worked on this a little more this evening and I'm still at a loss. I made new bolts, put a bevel on the edge, softened. Same results as above on the bake. So then I took the same new bolt, placed it on a poly plane, baked it, and it came out fine. I don't understand the difference between it baking on the bearing cap and on a plane. I know this has got to be something really stupid and simple I'm missing. I'm to the point of just doing an overlay of the good bake in photoshop, but I'd still like to know why the actual bake isn't working.

    Here's a shot of the new bake.

    Normals_2.jpg
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  • MoP
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    MoP polycounter lvl 18
    Have a look at the wiki page on normal map baking (the rest is a good read too).

    http://wiki.polycount.net/Normal_Map#Baking

    Basically the problem is, as you can see from your test bake on a plane, it's tracing from the lowpoly to the highpoly in a straight line because the plane is a flat surface.
    However your lowpoly mesh is a complex curved surface so the rays that it casts to capture the highpoly information go out radially instead of planar. That results in the artifacts you're seeing.

    The only way to fix this is to either harden the edges around the lowpoly cylinder cap, or as others have said, bevel the edges of the lowpoly cap to make the ray casts in a more unified outward direction.

    You can also edit the Envelope in Maya to control the ray cast direction better, read the Maya Help on that if you don't know how to do it.
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  • Spur
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    Spur polycounter lvl 6
    Ok so I finally got it to bake correctly. I kept thinking that my issue was in the high poly mesh, when in fact it was the low. I see that now. My question is, am I trying to translate too much detail with a normal map in such a simple low poly mesh? I've included screenies of low poly mesh as well.

    Thanks again everyone for all the help and putting up with my noobishness. :poly124:

    Normals_3.jpg
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  • bugo
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    bugo polycounter lvl 17
    image is not showing...
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  • bbob
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    bbob
    its a good idea to make several bolts, bake them to a plane, and cut-and-paste them to your maps as needed. Speeds up the process and saves you from fubars such as this with minimum fiddling.
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  • Spur
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    Spur polycounter lvl 6
    bbob wrote: »
    its a good idea to make several bolts, bake them to a plane, and cut-and-paste them to your maps as needed. Speeds up the process and saves you from fubars such as this with minimum fiddling.

    I definitely hear ya! I had already started considering photo shopping them but part of me just really wanted to know why it was not baking correctly. lol
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  • EarthQuake
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    EarthQuake mod
    bbob wrote: »
    its a good idea to make several bolts, bake them to a plane, and cut-and-paste them to your maps as needed. Speeds up the process and saves you from fubars such as this with minimum fiddling.

    Why not just copy paste them in 3d? I see people give this advice pretty often but it is quite puzzeling. It takes about as much time to copy/paste in 3d as it does in 2d, but 3d has various benifits:

    1. You cant rotate your normal map in 2d
    2. When you have real 3d geometry, you get get correct AO on it
    3. When you have real 3d geometry, your bake is going to come out nicer if you have even slight distortions in your uvs
    4. If you have any variance in texal density on your uvs, you will spend a bunch of time scaling your pasted normals in PS just to make them consistant

    So, even if it takes a tiny bit longer to copy paste in 3d, there really just is no benefit to me to doing it in 2d.
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