3DS Max smoothing problem on model (3DS Max using materials for smoothing reference?)

thunderysteak

I have a symmetrical human gib model with a non-symmetrical texture/material with custom UVW. In 3DS Max, when I assign a smoothing group to the mesh, it creates this artifact in the middle of the model all around (Using this as an example since have this model currently open). It also causes non-smooth transition between different materials on a same model.

Is there a way how to get around this? I pinpointed it to materials having an effect on this since without assigned material, the model is absolutely fine.

musashidan

Is the texture created in 3d or 2d? Are you sure it isn't a UV seam?

thunderysteak

It was created in 2D. It is in fact a UV seam (didn't knew what it was, had to look it up) and it goes straight through the area where the issue is (if the green lines when Unwrap UVW shows that).
 

Is there a way how to get around this without editing the UV map?

musashidan

Anywhere that you have a texture seam the continuity of the texture applied will break.

People traditionally hide seams to minimise the effect. Or you could use Viewport Canvas or any other 3D texturing tool to clone/paint the seam away. Or you can stitch the UV seam back together if this doesn't result in noticeable distortion. 

thunderysteak

musashidan said:

Anywhere that you have a texture seam the continuity of the texture applied will break.

People traditionally hide seams to minimise the effect. Or you could use Viewport Canvas or any other 3D texturing tool to clone/paint the seam away. Or you can stitch the UV seam back together if this doesn't result in noticeable distortion. 

I meant that it makes an artifact on the model itself, the texture is totally fine even with texture seam. 
For example, this part of a model uses the same exact texture file but uses Multi/Sub-Object material. The bottom and top part uses different material IDs (which I require to have)

Now if the model uses only one material ID, it's smooth.


This is what the issue is.

Eric Chadwick

That's bizarre.
Same material in both ID's?
Does it also occur with diffuse shading only?
Realistic vs. Shaded viewport mode?
What version of Max? 
Which preview mode... Show Shaded/Realistic Material in Viewport flyout?

thunderysteak

Eric Chadwick said:

That's bizarre.
Same material in both ID's?
Does it also occur with diffuse shading only?
Realistic vs. Shaded viewport mode?
What version of Max? 
Which preview mode... Show Shaded/Realistic Material in Viewport flyout?

Same texture (Body.png) on both IDs 
Yes it does, it also happens when exported from 3DS Max into a game engine (Source/Whatever Skyrim runs on) so it's not just a viewport issue.
3DS Max 2012 with SP2 and fully patched 

Basically on models I did not made I used to get around this issue partially by selecting all vertexes, breaking them and then welding them together with the force of 0.01 which basically recalculated the smoothing groups but it doesn't work sometimes. 

Eric Chadwick

Maybe you could override the auto vertex normals using Edit Normals?

thunderysteak

Eric Chadwick said:

Maybe you could override the auto vertex normals using Edit Normals?

That fixed it! Thanks!

musashidan

Eric Chadwick said:

That's bizarre.

Indeed.

Try as I might, I couldn't reproduce this. Is the mesh ripped from a game? Is it your own, or what format did you import it as?

Could you upload it so we can take a look?

thunderysteak

musashidan said:

Eric Chadwick said:

That's bizarre.

Indeed.

Try as I might, I couldn't reproduce this. Is the mesh ripped from a game? Is it your own, or what format did you import it as?

Could you upload it so we can take a look?

It's ripped from WoW, supposed to be ported to SFM for a friend.
https://my.mixtape.moe/jatvxu.fbx
I didn't modify this one and is exported straight from WMV 0.8.5

musashidan

Just had a look at the file. The geo is broken which, in turn, is why there are so many crazy UV seams, and also why the normals are split and causing shading issues.

Basically there a 1500 or so isolated(floating/unattached) vertices and wherever you are seeing those seams is because all the verts are unwelded/split along those edges.

To fix it you can add an Edit Poly/Mesh modifier below the Skin mod(or turn off 'always deform' in skin and do it at base level) and use the 'remove isolated verts' to clean out the dead verts. Then CTRL+A to select all verts and weld with a very small threshold. This will effectively weld the verts and unify the normals.

Mark Dygert

What musashidan suggested should work, but going back down the stack and messing with the vertex numbering and alatering the geometry is dicey and could mess the modifiers higher in the stack, like skin.

Here is what I do to avoid that:

1. Copy your mesh
2. Collapse the stack
3. Weld everything and get it cleaned up
4. Apply the skinwrap modifier and target the old mesh 
5. Animate the skeleton and adjust the skinwrap values to get it as close as possible
6. Inside of the skinwrap modifier, convert it to skin
7. Delete your old mesh and remove the skinwrap modifier from the list

TLDR: Make a copy, make your edits, transfer the skin weights

musashidan

@Mark Dygert welding those verts back together shouldn't affect the skin mod as they would have been split from the originally weighted vert. I was thinking the same when looking into this but I tested the rig and the skinning remained intact after the fact. A  cheap hack compared to your method but it seemed to work fine.