[PANIC] Having trouble baking multiple UV islands

laylala

Hello polycount

I'm learning both Maya and Xnormal for baking and I'm having trouble understanding the baking process. 
From what I understand, you can only bake objects that are in one uv island 0-1?

I've seem people having two or more baked normal maps for one character. how do they bake more than one map when all we can have is one uv island 0-1?  ex) www.artstation.com/artwork/Ko1GG amazing art by Ana Mendes showing multiple normal maps.

I feel like I'm missing something here..

what I do is I merge all the HP objects and LP objects. So now I only have two objects. Then I want to bake normal map but there are some parts that I don't want to bake. 

ex1)
I lay out face and eyeballs in one UV island. But I only want to bake the face because eyeballs don't have any details.

ex2) 
I have two UV islands, one for body parts, and one for clothing.
I want to bake every objects on these two islands, but people say I can only have one 0-1 islands?! and yet lot of artists managed to successfully bake two beautiful normal maps?!

This is so confusing to understand..

I would like to hear what others approach when they have many objects with multiple UV islands but want to bake certain amount of objects. 

thanks for reading this chaotic post, as I'm panicking a bit..  help will be truly appreciated.

CarlCraft

It's common to use multiple materials for models that need more details, such as characters. In your example you see the character has one material for the head, one for the body. The artist is baking the two parts separately, and making two different materials with two different sets of textures for each part.

Again from your example: Top part is baked (and painted etc) from the head, bottom part is the rest of the body

This means that the artist took the highpoly head/hair and baked onto the lowpoly head/hair, which indeed is using one uv island. A texture is generated, lets call it Normal_Head. Then he/she took the rest of the bodys highpoly and baked onto the lowpoly body which is using its own uv island, generating texture Normal_Body.
Now there are 2 sets of textures baked, we create 2 materials and call them Material_Head and Material_Body. Now we make sure the materials are using our corresponding textures. When we have our materials set up, we apply them to our lowpoly models parts, so the head is using Material_Head (which is using Normal_Head) and the body is using Material_Body (which is using Normal_Body).

Does that make sense?

laylala

@CarlCraft

Thank you so much for your explanation. yes now I see that a lot of people are baking head and body separately.. I was doing it wrong by merging every single objects. 

So let's say I baked them separately, one for head and one for body, but isn't there still only one 0-1 uv island to place both of them?
If I select both of them to be visible their UVs will overlap in 0-1 UV island.. 

OR is it that once the maps are baked separately it doesn't really matter how many uv islands I have because things are already baked? so I just place them wherever on the uv map editor?(in Maya) They can be outside of 0-1 uv island? 

CarlCraft

Yes, you still have to bake inside the 0-1 UV island. Going outside the UV only repeats the texture. This is a common technique when working with environments. Say you want a lava landscape, you make a texture that loops seamlessly. So, the texture would look like this:

And "outside the 0-1 UV island" it would keep on repeating:
Looped parts are desaturated just for demonstartion purposes. This way you can get have your environment as big as you want without having to make one huge texture.

But in your case this won't be necessary. You don't need to loop your texture. In any case, you always bake inside the UV island, otherwise you will have a lot of artifacts. But yes, when you select both your body and head they will overlap and that's fine if you intend to bake them separately. Just make sure head parts don't overlap in itself and same for body. But always place your UVs inside the 0-1 island.

McDev

laylala said:

@CarlCraft

Thank you so much for your explanation. yes now I see that a lot of people are baking head and body separately.. I was doing it wrong by merging every single objects. 

So let's say I baked them separately, one for head and one for body, but isn't there still only one 0-1 uv island to place both of them?
If I select both of them to be visible their UVs will overlap in 0-1 UV island.. 

OR is it that once the maps are baked separately it doesn't really matter how many uv islands I have because things are already baked? so I just place them wherever on the uv map editor?(in Maya) They can be outside of 0-1 uv island? 

When you apply different Materials/Textures to parts of one object what happens internally is that you create two seperate meshes. So even if your editor shows you both UVs overlapping each material will only be renderd with the associated mesh, in that case Head and Body. It is basically the same as when you seperate them in two meshes by hand.

Eric Chadwick

Why is this in Career & Education. Tech questions belong in Technical Talk. Moving this for you.

laylala

@CarlCraft @McDev

That's good to know! I was mostly concerned about overlapping UVs when working with separate meshes.
Thank you so much for answering my questions! It really helped me understanding a lot about uv and baking. 
I really appreciate you taking time to share your knowledge  

CarlCraft

Eric Chadwick said:

Why is this in Career & Education. Tech questions belong in Technical Talk. Moving this for you.

When I first replied to this thread it was in Technical Talk  Someone maybe sneaky-moved it?

laylala said:

@CarlCraft @McDev

That's good to know! I was mostly concerned about overlapping UVs when working with separate meshes.
Thank you so much for answering my questions! It really helped me understanding a lot about uv and baking. 
I really appreciate you taking time to share your knowledge  

No worries good luck!

Eric Chadwick

Mod War!