[Maya] Vertices displaced when smoothing [Solved]

daniellooartist

Issue

-Appears when smoothing. I would prefer to solve the problem normally as opposed to import/export obj. Below the image is a .ma file you can download yourself.

File: https://www.dropbox.com/s/nhtc1uj2lvakjwf/reload.ma?dl=0

Steps Taken To Isolate Problem

-Issue does not occur when doing a smooth mesh preview with the EXCEPTION of 1 face

-Deleted face. Error moves up another face. (edited)

-Continued to delete the face ring one face at a time and noticed the error moves up. (edited, throttlekitty's post)

-Selected face ring, delete and rebridged. Fixed. (edited, throttlekitty's post)

-Infered that the root cause of the problem has something to do with the way I created face ring or edge ring. (edited, throttlekitty's post)

-Issue only occurs to this one mesh object.

-Deleted all items in the scene except the problem mesh and saved an isolated file.

-Deleted UVs.

-Deleted history.

-Optimized scene.

-Cleaned mesh with the following settings.

  -Select matching polygons.

  -Apply to selected objects, Keep Construction History.

  -Lamina faces.

  -Nonmanifold geometry, Normal and geometry.

-Merged all vertices with a tolerance of 0.01.

-Unlocked normals.

-Ensured normal directions were correct.

-Ensured there were no faces inside of edges.

-Issue ONLY occurs with 1 subdivision.

-Hardened all the edges.

-Exported and reimported OBJ. Again, I do not want the lazy solution, I want the correct one. I did this so I can infer that the root cause is not mesh related.

-Combined with cube (Edited)

-Deleted history (again)

-Optimized scene (again)

-Cleaned mesh (again)

Root Cause

-Extruded face from edge with zero width

-Exported and re-imported OBJ

Resolution

-Check the following before exporting an OBJ

-Enable display boarder edges

-Ensure only the intended boarder edges are visible

-Marquee select the boarder edges that are not intended boarder edges

-Edit Mesh > Merge

-If that fails, select both vertices and merge vertices with minimal tolerance.

Specs

Maya Version: Maya 2016.5 Ext 2 (64bit)

OS: Windows 10 Pro (Build: Latest)

Video Card: Nvidia GeForce 980 X (Driver: Latest)

CPU: Intel Core i7 3930K

Mirror Threads

https://gamedev.stackexchange.com/questions/154813/2-vertices-displaced-when-smoothing

huffer

Have you tired combining it with a cube? Select the cube, then the mesh, combine, delete cube then delete history and optimize scene.

daniellooartist

oh, yes. I didn't note it the first time but combining with a random cube does not work. 

throttlekitty

This is what I see on my end in smooth mesh preview but in 2018. (win7, gtx1080ti) I also get this error:
// Warning: The OpenSubdiv Catmull-Clark subdivision method cannot be applied to non-manifold geometry. pSphere3Shape will use "Maya Catmull-Clark" subdivision method for Smooth Mesh Preview.

You managed to get an extra edge here and on the mirrored side, Cleanup doesn't seem to want to pick this one up as you noticed. I'm able to verify this by box selecting over that edge and seeing that 2 edges are selected in the polycount HUD.

Since there aren't also extra vertices, I was able to correct it by deleting one of the adjacent faces followed by a Fill Hole.

daniellooartist

I found the 2 edges in 1 you mentioned. I deleted the edge and filled the hole. The issue still occurs. What I noticed is an odd set of faces inside of my face. Even when I delete that face and append it, I still receive the error, just in a different spot. I can fix this problem by bridging the entire ring of faces. (example file at the bottom)



I appreciate the solution. Deleting the face and filling the hole is the approach I normally take. I could write this off as a memory that even my ECC cannot prevent. I don't think that's the case. Problem is that I do have to do this a LOT! So much so that I end up wasting what adds up to hours worth of time. It would make magnitudes more sense to infer that this is caused bad user practice and said bad practice is just being repeated over and over again. Me nor anyone else has discovered what that practice actually is.

When I created this object, I took a sphere with x number of sides, cut it in half, and merged it with an open cylinder with the same number of sides. After I merged them I merged all the vertices. I noticed something similar happened with a previous mesh I made with the same trick (merging 2 objects and stitching their verts) Does this somehow fuck up meshes?

File: https://www.dropbox.com/s/w7j20xvx8ngi6az/reload2.ma?dl=0

poopipe

The later issue pictured is two edges sharing the same vertices - that is what that non-manifold complaint is referring to.
It's surprising that cleanup hasn't identified the issue but such is life.. 

You can fix the open (dual) edges by selecting them and choosing merge border edges.  Much quicker than  deleting faces and recapping. 

Why did it happen? 
Sad to say it, but this sort of thing is very common when you model in Maya. Unlike with a proper modeller there is no protection against generating crap geometry and in a lot of cases even the simple tools just don't work properly.  
I suspect this specific issue comes about when welding verts on closed loops - It's not beyond the realms of possibility that maya loses track of relevant edges as the vertex order shifts around and forgets to merge them.

Deleting your history every 30 seconds and/or offering the occasional blood sacrifice can lead to a quieter life but neither are guaranteed. 

Practically speaking: 
in a case like this you would have been better to leave a gap between the half sphere and cylinder and use Bridge to close it - that at least ensures that you have valid edges (vertex order won't change which is a big help).  

daniellooartist

You might be onto something. Now that you mention it, I have noticed the common factor between combining and welding together 2 shapes is that they both always have closed loops. Do all of you guys always smooth your mesh and check for smoothing errors after you merge a ring of verts as if you’re expecting something like this to happen? 

daniellooartist

I’m on my phone now so I cannot edit anything now but later tonight I am going to mark this as [solved] until further issue similar to this one come up. When they do, I will link the thread.

daniellooartist

Once again you guys have been a phenomenal help and I am very greatful to the art community.

throttlekitty

I sanity check my models throughout, checking with smooth preview is usually pretty quick to do. Like poopipe says, Maya can just get hung up and do weird stuff, and it's not always something predictable. (thanks for the merge border tip, that never occurred to me that it was considered open). I also have delete history on a marking menu, I clear it pretty often for most modeling. Hell, just a couple weeks ago the quad draw tool was doing that double edge thing constantly while I was doing a retop- super annoying.

I'm also superstitiously wary of using Bridge for the simple fact that it used to be a great way to create non-manifold geo if the result will be a closed shape. So that's one example of something that I expect to go poorly and will always check right afterward.