Questions regarding texturing, UV and AO

[Poi-son]

Hi,

I’m new to Blender and have some newbie questions that hopefully someone can answer.
I’m currently working on my stylized character and modelling part seems fine. I’m now on UV mapping and texturing stage where I have some trouble.

I’m currently using Blender 2.93.5 and working with Cycles renderer.

UV mapping questions

1. I often find myself repeating some steps during UV mapping. i.e. Giving more space to an island by scaling it further. Yet, when I find the need of changing something in the mesh and re-UV map whole thing, my customizations for specific parts would be gone. Is it somehow possible to “pin” or preserve the already-edited islands that I’m happy with?

2. How one can find his/her way among many UV islands? I mean, for the sake of high details, I have a bunch of seams here and there, thus, creating around 15-20 pieces of UV islands. When I export these and import them in Photoshop to paint and edit them, I can barely name which island represents which part of the mesh. How do you experienced users deal with this?

3. This question is actually related to 2nd one. Is there a 3rd party plugin that “magically” converts UV islands into Photoshop layers? It’s really hard and time consuming to every time make selections with lasso tool and distributing all tens of islands into several layers in Photoshop, especially, if I make further changes to the same UV layout.

4. Syncing selection issue. I found it quite frustrating to be able to do one thing at a time when UV mapping. By this I mean, if I do not sync viewports between mesh 3D and UV window, I’m able to select UV islands, or else this option is hidden. But, if I toggle off “syncing” then, I have to select whole mesh in order to see the UV layout in the UV window. But this does not help because when I do selections in UV window, I cannot see the corresponding part in the mesh view since because whole mesh is already selected. If I turn on syncing all my selections are reflected between those two windows but this time, I’m unable to make “island selections”. Why is so and is there any preference to be turned on that I’m not aware of?

AO question

What as far as I understand from AO maps, it mimics depth of ambient lighting to a degree to create more realistic volumes and surfaces and as far as I read, it does not matter what kind of a light you use in the scene. But, somehow sometimes my AO maps look having way more contrast (exaggerated in the worse direction) compared to some others where a good amount of AO is applied. What is the cause of this if the scene lights do not affect the AO map directly? Material or some nasty nodes in the Shader Editor?
What are the optimal settings to get nice but considerably enough AO along with my UV layout?

Thank you anyone and everyone who could bare with my long post up to now and have time to answer any of these questions.

Cheers,

[sozap]

Hello and welcome to blender artists !

I can give a few answers, but generally I try to avoid using UVs because as you’ve guessed it’s a bit painful. But for a character it’s hard to do differently.

1/ Yes, it’s always better to finish modeling before fine tuning the UVs, you can select a part of a mesh and unwrap only these part, but if for example you have scaled the nose then you probably need to unwrap the whole face again even if you’ve changed the eyes.

2/ You can use multiple UV layers, multiples materials, and also separate your character in different objects when that makes sense.
That way, you’ll have in photoshop, one texture for the face, that belong to a Face object, with a Face material. Same for other parts.
If you need to export your character to a game engine and prefer having all the UV and texture in one image and the character as a whole mesh, that can be done latter by baking the textures from several mesh/UV/Materials down to one object with one texture. But as for question 1 , it’s better to do that in a final step.
If you don’t plan to go real time, you can do whatever is the most easy to work with. No need to have one big object with one big material.
Another option is to paint in blender on the 3d mesh, that way you don’t care if the UVs are messed up, but it’s a different workflow than in photoshop (no layers).

3/ I don’t think so, but maybe… As with answer 1 , it’s better to work in steps and try to avoid jumping back and forth between modeling and texturing. You can make temporary materials while modeling so you get a rough idea of how it will looks in the end, that’s a good practice. But avoid doing texture work unless you’re sure that the model is OK. In production it really cost a lot to change a character once it’s ready for animation, because it impact modeling, rigging, UV and textures, so even for a small change in modelling, it as to go through all these changes. This append sometimes, but a lot of effort is put into avoiding these situations. Unless you have enough budget to allow all these people involved to redo their work, but working that way you’ll put all the CG artists to despair, even more if you’re working alone.

AO question :
AO gives indirect shadows when two objects are near each-other because they catch less bouncing light. As you said, it’s not dependent on actual light, it’s an approximation used a lot in old school CG pipelines. Actually, with Cycles bouncing light and shadows are calculated automatically, there is no need for AO anymore. But still it can be used to give a texture or a render a bit more contrast, or to be used in shading/texture to make some variations in materials. That’s why it’s still there even if it’s less useful than 10 years ago.

The difference you’ve noticed comes probably from a settings that sets at which distance two objects starts to occlude themselves.
In Eevee it’s here :

In Cycles, it appears that the panel have been moved, I found this :

So Ao isn’t influenced by the light, but the scale of objects according to the AO distance setting.

You can see how this apply to your scene by going into render mode and display the Ambient Occlusion render pass.

It should be the same once you bake.

[Poi-son]

@sozap

…avoid using UVs because as you’ve guessed it’s a bit painful. But for a character it’s hard to do differently.

Do you use Texture Painting in Blender? What is the alternative to UVs?

@sozap

1/ Yes, it’s always better to finish modeling before fine tuning the UVs, you can select a part of a mesh and unwrap only these part, but if for example you have scaled the nose then you probably need to unwrap the whole face again even if you’ve changed the eyes.

As for my first question, I think “pin” selection within Right-mouse context menu does what I want. I tried it and it preserves the scale and location of the islands that I’m happy with and re-unwrap the rest which are not pinned. I found about this just after posting these questions. Sometimes I can’t see the answer that lies in front of my eyes.

@sozap

If you need to export your character to a game engine and prefer having all the UV and texture in one image and the character as a whole mesh, that can be done latter by baking the textures from several mesh/UV/Materials down to one object with one texture. But as for question 1 , it’s better to do that in a final step.

Actually when I designed my character as a collection of different objects, the method you said applied perfectly. But my only concern is about rigging and animating and then importing into Unity. Would I have problems with these steps if I keep most of the detailed parts as single objects (as far as Loc, Scale and Rot are all 1.00 for each)?
And apart from rigging and importing into Unity, how am I to combine all objects’ textures into one in the final step and remap it again? Do you know any tutorials on such a procedure?

@sozap

But avoid doing texture work unless you’re sure that the model is OK. In production it really cost a lot to change a character once it’s ready for animation, because it impact modeling, rigging, UV and textures, so even for a small change in modelling, it as to go through all these changes.
…
but working that way you’ll put all the CG artists to despair, even more if you’re working alone.

Since struggling within these areas up to now, I can clearly sympathize with CG artists and understand what you mean.

@sozap

Actually, with Cycles bouncing light and shadows are calculated automatically, there is no need for AO anymore. But still it can be used to give a texture or a render a bit more contrast, or to be used in shading/texture to make some variations in materials. That’s why it’s still there even if it’s less useful than 10 years ago.

When I just export UV layout, I have to paint them in Photoshop with no depth on these textures. So how is this achieved with Cycles? I’m ready to give up extra AO work load.

@sozap

In Cycles, it appears that the panel have been moved, I found this :

I’m gonna check this one out!

And lastly, thank you very much for taking your time to answer my questions. Much appreciated!

[sozap]

hey !

@Poi-son

What is the alternative to UVs?

You can do more work on the shader nodetree , use some procedurals, or map image using the Box method , like in this example : https://www.youtube.com/watch?v=ckehwWoqubo
There are other small technical tricks but lets keep it simple.
For a character especially the face it’s hard to totally avoid some UV + painting anyway.

For the face I tend to do some unwrap without taking too much care, then use blender to paint a very simple color map without details. Some details like skin pores, skin variation, I map it using another texture with Box mapping. Then do other UVs with special parts like mouth and eyes to add wrinkles. I try to avoid to work many details in a 2D software to avoid jumping back and forth between the two softs. But there is no perfect answers, what matter is the result and not to struggle too much with technicalities .
Here is the kind of result I get on a WIP project :

The textures used for the face:

The shader’s nodes :

@Poi-son

I think “pin” selection within Right-mouse context menu does what I want

Awesome, I forget about that one !

@Poi-son

And apart from rigging and importing into Unity, how am I to combine all objects’ textures into one in the final step and remap it again? Do you know any tutorials on such a procedure?

I don’t know much about Game engines and their constraints, you can ask someone else here to be sure you don’t get stuck at some point.
The trick to remap everything to a unique texture is the same trick that is used when doing sculpts.
You have two mesh, one for sculpting and the other for using in animation or game engine, and you bake some information from one object to the other :

High poly to Low poly workflow : Blender Cycles Baking (5)

But instead of doing that to get a normal map like here, you’ll do that for color and other maps if needed. You can also bake several objects (HighPoly) to a unique object(Lowpoly) You probably don’t need to use a lower poly mesh if you’ve already have a light version suitable for animation.
Maybe there are better ways, but I’d do it like that.

@Poi-son

When I just export UV layout, I have to paint them in Photoshop with no depth on these textures. So how is this achieved with Cycles? I’m ready to give up extra AO work load.

Hum, I hope my explanations will make a bit of sense :
Historically AO was used for texturing or rendering (as a post process) to tweak and increase the shadows and thus make something more realistic.
Sometime that also helped to cut down rendertimes by rendering AO separately, or not rendering AO at all and having it in the textures.
Nowadays while using renderers like Cycles it’s still common to add shadows/AO in the textures and sometimes also in the render sometimes only by habit. Theoretically the render engine takes already care of all that, because the way Cycles works, the indirect shadows (AO) and indirect light (GI) is part of the same thing and you can’t disable it like in the old school renderers. In the end, by still putting AO in the textures, or in the renders, we add shadows over shadows.
All that said, even if it’s not correct, sometime adding a bit of AO can add a bit more contrast, and while not being 100% accurate it can work better.
Sometime instead of AO you can add a slight darker color in the textures, like in the nostrils you have a darker, reddish tone because of the blood vessels more present in this area.
You can also add a darker color under the hair , so the skin doesn’t pop behind the hairs, that generally helps.
For objects, you can add a layer of dirt (slight darker color) where AO is present because generally these area tend to get more dirty especially if you want to make them aged.

To sum up, using AO can be helpful sometime but not always needed as the renderer already takes care of indirect lighting and shadowing. You can have textures that are quite flat and let the renderer take care of shadowing. Maybe try different things to see what works before exporting all the AO maps, that can takes quite some times.

All that said, I’m giving you advices in the dark because I don’t have a clue of what you’re doing.
So take all this with a grain of salt …

Good luck anyway and have fun with blender !

[Poi-son]

@sozap

All that said, I’m giving you advices in the dark because I don’t have a clue of what you’re doing.
So take all this with a grain of salt …

Good luck anyway and have fun with blender !

Thank you very much for the detailed responses. I’ve already had a lot to cover and the information you’ve provided is more than enough atm!
I’ll try to digest all these bits by bits. I’m always after the workflow of the others which is truly invaluable info that’s hard to find among generic tutorials.

Thank you again!

[sozap]

You’re welcome !
Yes, in the end, different people, different ways of doing, with time you’ll find with what you’re most a ease with. All have their pros and cons. As long as you get a cool result and don’t have the feeling that you’re struggling with the software it’s more than enough !