PBR Changes to UV Mapping Best Practices
Hi, I have been hearing from some engineers that when UV mapping for the new Physically Based Rendering pipeline for Unity 5, that the new best practice is to never overlap UV's.
So for an oversimplified example, if you had a symmetrical butterfly, historically, and if you didn't care about texture repeat, you could overlap the UV's of the left half of the butterfly with the right half and then scale your UV's up to get more definition in the same amount of texture space. However I'm being told that no longer plays well with reflection probes and real-time and baked lightmapping.
I had not heard of this before, so I thought I'd ask.
So for an oversimplified example, if you had a symmetrical butterfly, historically, and if you didn't care about texture repeat, you could overlap the UV's of the left half of the butterfly with the right half and then scale your UV's up to get more definition in the same amount of texture space. However I'm being told that no longer plays well with reflection probes and real-time and baked lightmapping.
I had not heard of this before, so I thought I'd ask.
Replies
You might be thinking of lightmaps where there an be no overlaps?
You've been told wrong. It would be true for lightmap UVs, but Unity already calculates its own secondary set of UVs specifically for lightmapping.
Great, I had hoped so
In the import settings for a model you check the Generate Lightmap UVs checkbox, that's all. It will auto-generate a secondary UV set for you.
If you import a mesh with a UV layout already in UV channel 2, Unity can use that one for Lightmaps too - a quick procedure would be to copy your main unwrap to channel 2 and use something like Layout in Maya's wnwrap window or pack in Max's. This makes it a little easier to get a really efficient, even distribution for your lightmaps compared to waiting out the Generate UV's process in Unity.
I`m a little confused too. And sorry about the noob argument but I just started to study about how to produce PBR materials and etc. I choose take Quixel Suite to do some tests (So I`m limited to talk about this workflow only. Maybe Substance Painter is more flexible).
Quixel asks for some maps, a minimum of color map, normal maps (tangent and object space) and ambient occlusion before anything else.
My workflows to generate ambient occlusion asks for non-overlapped UV in order to avoid fragments (even using some automatic procedure as Unity Lightmap or whatever the non-overlapped UV is a need for AO).
Of course, we can use the UV1 for that purpose in most cases but that don`t look the case of Quixel Suite since whatever it takes, it`s oriented to UV0.
I can be missing something, and I really hope to be that the case, but in order to produce the PBR material in Quixel Suite, Non Overlapped UVs is needed.
Please, someone say:- You a completely wrong.
Quixel's dDo has no problems with overlapping uv's.
But if you want to use a world-space-normalmap for your dDo workflow, you have to unwrap your model without overlapping faces, otherwise your rendered world-space-normalmap is useless.
If you don't need a world-space-normalmap for texturing, you can unwrap your model with overlapping faces.
Your right with the AO baking. You need a non-overlapped uv.
But you can offset the overlapping faces for the baking process. After baking you can reset the faces and you will have a ao without fragments and a overlapped uv.
sry for my bad english
Quixel's dDo has no problems with overlapping faces in your uv.
But if you want to use a world-space-normalmap for your dDo workflow, you have to unwrap your model without overlapping faces, otherwise your rendered world-space-normal is useless.
For the ambient occlusion map.
You can offset your overlapping faces for the baking process.
After baking you can reset them and you will have a ao without fragments and a uv with overlapping faces.
sry for my bad english