Normals issue when opening existing file...

[Anonymous]

Hi there, hope this is the right place to ask this.
I'm having a problem at work with Maya (2014 but I'm sure I've seen this happen before on  other high-res models).

Opening certain existing scenes will show vertices on my high-poly model incorrectly, causing dark patches all over the model. If I manually edit the normals, then undo, the model will usually display correctly afterwards. The model occasionally does this during working on it also, the only remedy to which I can find, is re-doing all of the normals again from scratch.

I've tried locking the normals before saving the file, to no avail.


Much appreciated if you can help please!

[n8skow]

If you turn on 'display normals' are the normals actually flipping or is the shading just malfunctioning in the viewport?

[Anonymous]

Hi thank you very much for the reply. The vertex normals themselves change. The model will also render this way in both software and mental ray. If I display vertex normals after opening the model, then either:
Harden edges
Soften edges
Average edges
or Unlock normals
the problem corrects itself. If I then Undo the previous action the bug does not reappear, as though it never was there in the first place.

http://www.youtube.com/watch?v=bjOvHNNQnR0&feature=youtu.be

Sorry about the video quality, but basically it shows me open the file, 'Unlock Normals' to fix it, then spam undo until I cannot anymore to show it doesn't change back to how it was when I first opened it.

[n8skow]

Hmmm, are you carrying a lot of history on the object by chance?

[Anonymous]

Nah I delete all history very often when I know I won't be needing it for deformations and such.. bit obsessive about keeping a clean scene etc. I'm really surprised I can't seem to find much else on this issue. I had this problem first at work but I've been able to recreate it at home too now. I just model a mildly complex model, save it as .mb. Close Maya, open Maya, open the file and there it is all bugged up. Twice in the past its opened like this and stayed like it, requiring me to manually fix it also. 😕

[Anonymous · Accepted solution]

Issue fixed. Just noticed that Service Packs fix this issue -.-

Turns out I was experiencing this problem:
http://www.bytehazard.com/code/vertnorm.html