Mirroring UV's

Drekavac

Hi, I was lately working on a revolver model based on other artists concept art. I have high-poly and low-poly model. I wanted to practise hardsurface modeling, working with concept art and creating game assets. My question is about mirroring UV's. Is it a good idea to mirror all of the UV's, which means they would overlap, in order to save texture space? Would that have any bad infuelnce on e.g. baking normals in substance painter? (By mirroring UV's I mean unwraping model and after that applying mirror modifier - I'm working in Blender) All of the parts of high-poly and low-poly are mirrored so both sides are the same.  I've never done that this way, I usually unwrapp UV without any overlapping parts of unwrpped mesh.

High-poly model of the revolver

Kanni3d

Yes, this is super common to do, and you should almost always do this to save on texture space/maximize resolution. Analyze your model to identify and take advantage of overlapping parts that won't be seen at the same time (left and right side of the cylinder, trigger guard, grips etc.)

You'd only have to be mindful of any sort of details like text/graphics, as the mirrored side would have it flipped. Once you stack your uv's, make sure to move them over one full udim to bake properly.

Eric Chadwick

We have some info and examples on our wiki.
http://wiki.polycount.com/wiki/Normal_Map_Modeling#Mirroring

Drekavac

Thanks for tips and advice guys
@Kanni3d do you think I need to move my UV's over one full udim if I'm baking my normal map in Substance Painter? I read about moving mirrored UV's before baking normal on Polycount Wiki, but It seemed to me It was talking about baking normal map specifically in 3D application, where you model. 

Kanni3d

Always move it over a udim before you bake, regardless where you're baking it. Chances are there will be artifacting if you don't, as the baker will see the two overlapped uv shells and not exactly know where to place the information, most simply put.

Eric Chadwick

Kanni3D is right, this matters for all bakers. Also, make sure to only move the mirrored UV, not the original UV. The baker still needs something to bake.