2023 UVW mapping adds facets to imported cad geometry

[jasond240]

We work exclusively with imported CAD geometry and have noticed that adding UVW mapping to components creates really bad faceting in the model and render. This happens on multiple computers, in every Max 2023 file that uses uvw mapping. As soon as you turn off/delete the modifier, the faceting goes away. Even stranger is if you clone the object as a copy, the faceting goes away on the new object and performs as it should. With thousands of components, its not feasible to clone objects in order to fix this bug.

I tried removing materials from the object, assigning a different renderer, starting a new scene with only object and nothing works. I can open the same model in Max 2021 and everything works properly.

Example (top left is the original that has corona material, bottom is an instance has no material as a test, top right is a copy with the same UVW pasted as an instance)

And here is that same file saved to / opened in Max 2021. No faceting.

Any suggestions? Will have to revert to our install of Max 2021 if we cannot fix this issue, which is a huge pain.

Thanks!

[darawork]

Hi,

If you can, if the import is not too big, try selecting everything and adding one single Edit Poly Modifier to the whole scenes geometry. Then in 'Polygon' SubObject Level, select all and have a look into the Smoothing Groups at the bottom. Press clear all.

Hopefully that might help.

Regards,

[jasond240]

Oh this is very odd. I just opened the file I was testing with in the above post and the copied object I made now has faceting like the other objects. So it keeps resetting every time a file is opened.

If I add an edit poly on top of the UVW, and tweak the smoothing groups, it looks almost as it should minus some artifacts. This unfortunately isn't a viable solution in our case though as we have 1000+ object assemblies and it would be impossible to do this work-around on them all. We'd just revert back to our 2021 install if this is the case.

Here's another example from a different file that works ok in 2021. Smoothing group set to 2 on that flat face on both, left one is a copy.

Thank you for your help!

[darawork]

Hi,

That's unfortunate. Here is one more thing to test:
https://forums.autodesk.com/t5/3ds-max-forum/curve-smoothing-when-importing-from-autocad-to-max/td-p...

I work a lot with imported CAD files.  I personally prefer to model in CAD over 3DSMax, but that's just me. I started out using AutoCad first. I'm a lot faster at modelling in CAD, but I'm trying to get up to speed in MAX. That said, I'd be interested to hear if you tried modelling solely in MAX yourself, or the rest of the production line and just bypassing the whole AutoCad step. There are much more advanced Autodesk products lines out there now. AutoCad will hate me for saying this. I still like modelling in CAD though, it's nice and easy.

Regards,

[jasond240]

Models are created in Solidworks by our Engineering Dept. for internal projects or any other CAD software for external customers (rarely AD Inventor). We do not model anything ourselves. Files are exported to either IGES or STEP then we import using PolyTrans or Max's built-in importer. This method always works and everything has proper smoothing groups, until we add UVW in 2023 when the faceting shows up. Delete / disable UVW modifiers, faceting goes away. First time I've encountered this since I started with 3D Studio for DOS.

[StephenMF]

I too am running in to issues like this.
image 1 - straight import.

image 2 - With UVW added

image 3 - With an edit poly added - WORKS!?

image 4 - With a symetry added - NOT work!?

I suspect it has something to do with explicit normals vs. smoothing groups.
😕

[jasond240]

Your issue there looks very similar to what I'm seeing. It's really frustrating.