Sharing UV map for baking normal

Klo Works

Hi,
I just wondering if sharing uv map for baking recommended ? 

something like the image below : 


is it gonna be fine or I will get error when I baking ?




if this cube, I share the top with the bottom and the left side with the right side.
when I baking the normal map is it gonna be fine and perfect or I will get bad baking ?







 

loggie24

Are you asking if you can have two UV's in the same position in your UV space? If so yes, but both will end up exactly the same and if you for example paint on one side you will also paint on the other side automatically.

Klo Works

loggie24 said:

Are you asking if you can have two UV's in the same position in your UV space? If so yes, but both will end up exactly the same and if you for example paint on one side you will also paint on the other side automatically.

yeah, like if I have cube and I want to share the left with the right is the  process fine when baking ? 
that what I want to know , I am not talking about mirror baking. I am talking about share uv in the same model.  

like this model I want to share some uv is this situation will be fine ? or the baking will be not accurate.

loggie24

I'm not sure i get what you mean. Looking at the latest picture, both of the UV islands need to be in the UV space otherwise it won't work. Kind of shooting blindly here, explain further if i didn't get it.

Klo Works

loggie24 said:

I'm not sure i get what you mean. Looking at the latest picture, both of the UV islands need to be in the UV space otherwise it won't work. Kind of shooting blindly here, explain further if i didn't get it.

my bad I will explain it with more examples.



usually if you want to bake normal map for mirror object you take the half uv and send it to other side and bake it right.
for this example, it's not mirror object so doing this will be fine for baking ? as you can see I share uv island for the top  and bottom
so is this process is fine, specially in game engine ? 

another example : 


I share the top with the bottom, left with right and front with the back .
then I bake the normal map is this condition is fine or I will get error in the engine?

another one  : 



since the ornament all the same I decide to share the corners. 
I bake this one and it was fine, I just want to make sure doing this is recommended ? specially when dealing with game engine like unreal 
or it will cost problems ?

sorry sometimes my English become bad.

Eric Chadwick

If your triangulation is mirrored, the UVs can be mirrored. Same with re-use, if the topology is the same (including the connecting parts!) then you should be OK. More info here
http://wiki.polycount.com/wiki/Normal_Map_Modeling#Mirroring