Xgen Error: line 1: XGen: Failed to evaluate subd. <- What is this?

[Anonymous]

Shot in the dark but has anyone encountered this error before?

"Failed to evaluate subd. deer_base_groom,deer(30653:0.293201,0.319337)" etc. etc. etc.

I have sucessfully groomed and rendered a series of models except for this one mesh that is giving Xgen serious issues. The above error pops up on scene load and when I try to add any maps to control Xgen attributes, maya crashes consistently. 

I have tried to scrub this mesh as clean as possible and start over but no matter what I do I STILL get this "Failed to evaluate subd" error. 

The mesh is not a subD mesh and has no subd attributes whatsoever so I am not sure what "subd" has to do with this error.

This is a clean mesh with NO construction history whatsoever and no glaring issues with its various components. It checks out in the cleanup tool. It checks out in other apps: Modo, Max, Zbrush. In tests I have exported it as an obj and reimported it and tried to make a new description only to get the SAME error:

"Error: line 1: XGen:  Failed to evaluate subd."

Maya has a bee in its bonnet about this mesh, no matter how many times I export it, clean it, put it through other apps, start over, etc . and I can't figure out how to fix this. What could be going on?

[Michael_Todd]

XGen binds to the meshes subdivison limit surface and for some reason, this mesh appears to not subdivide correctly. There are no non-manifold or coincident points or faces? When you hit 3 for the sooth mesh preview do you see any wierd pulling of the wireframe on the surface?

Cheers

Michael

[Anonymous]

No...there is no strange subdivision when the mesh is smoothed or otherwise subdivided. I eventually rendered the mesh as a subdivision surface with a vray subd node and it renders fine...but xgen will not work on it. Mesh cleaners in modo, max and maya have found no odd issues with the mesh - no co-incident points or faces, no non-manifold geometry, no 2-point polygons or n-gons - nothing weird. The mesh will subdivide properly in all of those apps and in maya itself. Xgen will not work on it.

What I can tell you is how we eventually fixed this problem: If the mesh is exported as an obj and imported into Zbrush and Geometry > "Optimize Points" is run and the model re-exported back to maya...xgen will work properly. We have since run into this problem several times and every single time the only way to fix it is to bring the object into zbrush, "Optimize Points" and bring it back to maya.

This leads me to believe it has something to do with the meshes point order or something. Perhaps maya can add a similar point-optimization step to xgens initial setup. We have run into this problem on about every third mesh and the "Optimize Points" trick works in every case to fix it...but I am not sure how I would have fixed it without zbrush. It might make sense from a user standpoint to have an x-gen specific object cleaner so that meshes can be brought into alignment with how xgen will use them - especially when from every other metric they appear clean and normal, and work as such in every app.

[Michael_Todd]

It would help to know what the Optimize points did to the mesh. What is different about the mesh after the operation? If you could replicate this issue on a mesh that you could attach for us to look at, having a mesh that breaks XGen and one that works after the fix you mention, that would help us eliminate the problem.

Cheers

[wynandlens]

@Anonymous

Hi, I have been getting the same problem, and have found the reason for the error.

It is because of High Valence Vertices.

If you have more than 16 edges going towards a single vertex, you will get this error.

It usually happens with spheres. In my case, it was because of all the edges I terminated into a singe vertex at the back of the eye socket.

Now I'm not sure how to fix it, as my fur guy has done all the grooming already.

When I delete the edges, I stop getting the error, but that messes up the patches, and my fur goes all over the place.

Some help will be appreciated!

Thanks

[wynandlens · Accepted solution]

I've just solved it!

Select the faces around the high Valence vertex (The one with more than 15 edges going towards it).

Then go

XGen > Descriptions > Bind Patches > Remove Selected Faces

You won't get that error anymore when your geometry deforms.

-Although that means that you won't have hair/fur on those faces, but hopefully that will be covered up by other hair, or like in my case, I never needed hair there in the first place.

[Anonymous]

Wow. Fantastic work! This problem has been mystifying me for MONTHS. I'll need to go back and check my original model but I would imagine the problem is also with the eye-socket or inside the ear where many poly-crimes are hidden. Pretty sad that other hair systems don't have a problem handling this sort of thing out of the box but it's wonderful to finally have a solution!

[Michael_Todd]

Another thing you could try is to remove the faces from the binding, then delete edges to leave quads without changing the point order and count, then add the quads back to the binding by selecting and appending the faces to the patch.

Cheers

[max_schoenherr]

hi there, hi mike,

i wanted to create a tutorial about this:

https://youtu.be/DBvMxdOI17M

i managed to get the animation and the xGen fur running on my PC at home, with the 2018.2 maya version installed. i had to use alembic export/import to get rid of the error message mentioned in this discussion. when loading the mocap dancer and applying xGen prefabs to the skin the skeleton performed the dance, but both the skin and the fur froze at the initial frame, with the infamous error message.

so i selected the skin only and exported it as alembic, created a new scene, loaded the alembic file, which had no skeleton history, but the animation of the skin. i then attached the xGen to the skin as before, ran the simulation, and that is what you see in the video above.

however, on my studio machine this workflow produces errors as well. sometimes it works, sometimes it freezes the skin/fur at a certain frame. alembic does not seem to help either. attached is the file with the xGen description. maybe you are more lucky than i am.

since the mocap geometry in the content browser seems to be clean and tidy, i wonder why it produces this error message.

best,

----maximilian 

[Anonymous]

Спасибо, добрый человек! Твой совет помог!