Non-Manifold geometry

[Anonymous]

Hi everyone!

I am new to Maya and when I use the clean up command to see if I have nonmanifold geometry I get this (see image below)

I don't understant why Maya consider them as nonmanifold geometry. 

If anyone know how to solve this problem I would really appreciate it!

[daunish]

Diagnosing what is causing the non-manifold error can be tricky. Especially when looking at it in this view. Usually, it just means that something is off about your model. Can you upload it, we can take a look at what might be the problem? If not, you can look into this more yourself. I found this page that tries to break the problem down into digestible bits:
What is a non-manifold mesh and how to fix it - Sinestesia

[hamsterHamster]

Impossible to tell from the screenshot alone.. the selection you get is dependent on cleanup settings.

Unless you model for an engine that accepts manifolds, go for the actual cleanup Operation, not just selection, then merge the split edges.

These are settings for the soft poly modelling, yet in this project you might wish to activate Edge and Face cleanup options too.

[mihirsbcc]

Triangulate the geometry. Then from the Mesh Menu open the Qudrangulate option box. Uncheck all the check boxes and ok it. Maybe it will fix it. The alternate is run Remesh and Retopo. The article mentioned by Hamster is a great source for more info.

[Anonymous]

I can't upload my 3D model on Maya. I get this message : "Correct the highlighted errors and try again. The nonmanifold.mb content type of the attachment (application/byte-stream) does not match its file extension and has been removed."

Can I send it to you via an email address?

[mihirsbcc]

First you have to upload to your google drive or any similar storage. Then you have to use the link tab to post your share link. That is the way it works here. I do not think you can directly attach it here.

[Anonymous]

Here's the link to my 3D model : https://drive.google.com/file/d/1nDRiOvwt8B_pAuQFAPetRNpbFym9TMiF/view?usp=sharing 

[daunish]

So, took a look at your file. Besides in general, being a little messy and the geo really not being very clean. I couldn't find anything deeply wrong with your geo. What I mean is I couldn't find anything that would cause a huge issue moving forward.

Annoyingly, Maya has always seemed to develop problems with some meshes, and won't make up her mind about them, like in your case. What I've found works for me, is in these cases, export your geo as an obj, clean your scene, import the geo back in. In many cases, yours included, this solved the geo error.

I'd still clean your mesh, merge all the verts to deal with overlaps, and delete histories. But besides that personally, I think you're good to go.

Unrelated, but you can also always zip your files when uploading here.

Good luck!

[hamsterHamster]

After studying your modelling workflow, the conclusion is that one of causes of nonmanifolds is the "chaotic" use of mergeVertices tool. This often can cause crazy edge attachment, which turns naive poly face into a tail biting snake. When you add more edits, the underlying math becomes even more complex. Deletion of faces also is nonmanifold generator.

Luckily, you can detect and neutralize such issues with Cleanup tool, see settings above.

To avoid nonmanifolds, I would suggest merging the border edges instead, not vertices. And paying attention to face deletion - don't leave one vertex connection between two faces. Also, if you happen to extrudeEdges, do it only border elements.

On nonmanifolds, read more here.

[Anonymous]

Someone said in another forum that the problem is the UV mapping. By going to UV -> Automatic, it worked!! So now I don't have the problem anymore, but I don't understant why and how this command resolved the problem?!

[hamsterHamster]

Cool. The Cleanup shows nothing after this.. let's pop a champagne!

However.. I suspect, this is just brushing the topology problem under carpet, not getting rid of it. Try to select that face:

.. and, you will notice that some other parts are selected elsewhere. Cleanup will show no warning. And the model at all is fubared - adding edges, triangulating, obj importing/exporting, splitting-merging, cleaning up.. fixed nothing.

All that comes to mind is to go through problematic areas, deletion and surface recreation.

[mihirsbcc]

little messy ? Man there are hidden geometries inside some polys. Co-planner surfaces sitting on top of each other. There are n-gons , more than 4 sided faces, non planner polys . So it really needs cleaning. I do not get why there are so many faces they can be avoided.

Since it is a structure you probably will get away with that geometry. But it might cause problem when you go for rendering.

[Anonymous]

Do you know how I can clean it? I'm new to Maya so I don't really notice all these things

[mihirsbcc]

I would like to know what you are trying to model. Technically you are pretty much there. It is very common with newbies. Could you please post the reference?  and explain to me what is the project you are doing. In that way I can have a better idea to guide you how to clean up the model.

[hamsterHamster]

Nobody notices when they arrive to something new. In order to avoid mistakes, you should consider reading about non-manifold geo - how it can be made, and be aware of tool/action combos that cause it.

Optimizing your scene actually did not resolve its strange behavior - unmovable faces, offset component pivots and randomly moving components. I would not bet even on the optimized mesh, because it might backfire anytime. The wisest would be to use existing geo as a reference and go for full rebuild - there is not so much done yet, and you can vertex/edge-snap your new geometry. Also, consider splitting each room in a separate mesh, because it gives you more control over polycount and mistakes.

Best,

H

[mihirsbcc]

You nailed it.

[Anonymous]

I would love to know how you did the cleaning? Did you use the clean up command?

[mihirsbcc]

I am pretty sure he did it manually, look at those hole areas. You had a tones of edge loops running all over. That is called consolidation of edge loops. Now it looks clean.

[Anonymous]

My project consists in modeling ruins for archaeologists. After the modeling, I plan to apply a texture on this 3D model. This is the goal of my project.

[hamsterHamster]

Noone can hide the truth from the eyes of @mihirsbcc - I did it manually indeed.

Tried various methods and my aim was to decrease the amount of clutter, so I need to fix as little nonmanifold features as possible. Cleanup was more of diagnostic tool, as it wasn't able to do there a thing. Still, I was powerless against the issues that were inaccessible from UI, even the reTopo was pointless. That mesh is toxic, sorry.