UVW mapping for Normal + AO maps

Pingpang

Hi,

When Unwrapping UV's sometimes its good to share similar areas of the model with same UV space. Bearing this in mind, can I get away with this for creating AO and Normal Maps, or do I have to unwrap the model and designate it's elements to their own unique UV space? Could Anyone clarify this for me?

Thanks a bunch!
Pingpang

EarthQuake

Mirroring works well with most engines(they have to support it) with tangent space maps. You can't mirror with object space, and something like ambocc is fine to mirror if you want, since it has no real bearing on the lighting or anything like a normal map.

fritz

man...the whole tangent space/object space normal map thing is beyond me. can someone help me and pingpang w/a laymens terms explanation on this one?

Pingpang

Hey Fritz, I discovered what Tangent, Object/Local XYZ and World settings are just by testing them out on some simple objects and examining the results. I really don't have the 3d terminology down to explain it hehe.

Pingpang

Thx Earthquake,

So, when unwrapping UV map for normal mapping, it is common practice to share UV space still? Just seems weird since the normal direction is mostly unique.

You said if the game supports it. You think HL2/Source supports it?

Many thanks!

Eric Chadwick

Most engines seem to have problems with normalmaps mirrored across the center seam. You'll either get a big seam or a slight one. Best to stress-test it before going too far.

Fritz, this is old but might help.
http://forums.cgsociety.org/showpost.php?p=1276815&postcount=7

verybad

Difference between MAKING and USING the map too, I'd reccomend not including the mirrored parts during the normal bake, then mirroring them afterwords with some more UV work. I've had problems in Maya with trying to get it all at once. It may be different in other apps, but I'm Maya's bitch.

This may be obvious with characters but with complex props that use multiple mirroring techniques it can be less so.

Eric Chadwick

Oh yeah, good point. The way I solve this is to select all the mirrored UV chunks (the ones that face down, or -W) and move them 1 UV unit on either U (to the right) or V (upwards). Then the normalmap-caster disregards any UVs outside the 0-1 box, so I don't get overlap errors. But the game shader will still "see" those 1-unit-moved UV chunks. Hope that makes sense. Someone's gotta have a tut for that.