Baking Instanced Objects Sharing Same UV

[filibis]

Hi everyone,
I have repeating column objects (sharing same UV space) in my house structure. Do I have to copy high poly version of that column to each low poly column location as well (in order to bake mesh maps from high to low)? What would be the correct approach to this?

[CAGameDEV]

If you have 4 Columns as your High Poly, then you need 4 Columns as your low poly. If you've stacked the UVs on your low poly so all columns are overlapping, then you need to offset any stacked UV Shells before baking. Once done you can move them back.

[filibis]

I've basically 1 low poly column and 1 high poly version of it. I'm copying both of them to various places. And actually Painter bakes everything quite good and expected. But problem is FBX file becomes huge and I'm seeking to avoid that. Is this the only way?

Your suggestion (Splitting UV islands) confused me, because I had no issue baking with stacked UVs. And I would like to keep them stacked as it will be used in a big texture atlas.

[CAGameDEV]

It is well know you don't bake with stacked UVs, but if it works for you then you're free to use that workflow.

References:

https://polycount.com/discussion/66363/stacking-uvs-and-normal-map-baking
https://www.reddit.com/r/allegorithmic/comments/awcaqq/do_all_uvs_need_to_have_individual_space_in_sp_so/
https://www.reddit.com/r/allegorithmic/comments/8t928p/offsetting_uvs_for_baking_still_necessary/
https://forum.substance3d.com/index.php?topic=4737.0

[filibis]

In my other models, I started to have artifacts, so I tried offsetting my UV islands by 1 unit as suggested (kept only one in 0-1 space) but it didn't fix the issue. Ambient occlusion, curvature and thickness mesh maps seem to be having these artifacts. Is there any good tutorial that covers this topic?

[CAGameDEV]

Provide a copy of your mesh, low and high.

[filibis]

I can't share the above file but here is a similar test case that have the same issue: https://drive.google.com/file/d/1bZ3jH7_38VlkOYbPmPrgCDW6HC36Oho_/view?usp=sharing

[CAGameDEV]

Can you just post a link? I'm not requesting access from your Google Drive. You can make it public.

[filibis]

Sorry, I forgot to make the link public. You can access it now.

[CAGameDEV]

Sorry, I forgot to make the link public. You can access it now.

Since you're referring to AO here and not normal maps that is a bit different. Offsetting and baking for AO and bringing it back with such a mesh wont work like it does with normal maps because your mesh has variance per pillar so your AO cannot be the same per stack.

We know this is true because if you don't split it you'll see each pillar has different AO:

(STACKED)


(NOT STACKED)


I didn't realize in your initial post you were talking about AO baking, but no you cannot offset and bring back UVs for AO maps because each part will look different depending on the geometry surrounding it. You can get away with it for certain meshes, but with what you've shown there is too much variance.

I also noticed you need to fix up your _low _high set up:





See: https://forum.substance3d.com/index.php?topic=9869.0 (Vincent's reply)

[filibis]

Allright, I got it now, thank you for the explanation. It's sad that I'll need to unwrap everything in its own space as I'll lose so much texture resolution but seems like that's the only option (I believe painting AO would be hard and troublesome in this case as well).

[CAGameDEV]

You can make a second UV map just for your AO if you want.

See my post on this thread about that:https://forum.substance3d.com/index.php/topic,33948.0.html

It is near the bottom where I show how to do it.