Summary

Title:Hair/Fur offset when using motion blur on a CAt Rigged character or object
Category:Crash/Critical
Status:Closed
Posted By:1k0 ( Nicolas Brunet )
Date Created:2 December 2022

Problem

Description:

Hi Ephere team!
I usually add motion blur in post on my project, however when I tried to render my last project using Arnold motion blur in 3Ds max I discovered a new but.

Because of NDA I can't share the project captures of the bug but I was able to reproduce it in a simple scene setup:

I created a box, added a skin modifier using a quick CAT Rig as bones. Then I added a few ornatrix operators on the deformed mesh. Everything renders fine until I activate the motion blur option in 3ds Max physical camera, then all the hair/fur is offset from it's original position.

This issue is linked to the use of CAT, no issue when the hair/fur object is linked to a simple geometry

The issue occurs in latest version of Ornatric plugin in Max 2020 and 2023

Steps to Reproduce:

Create a box, create a quick CAT rig (Pelvis+ leg), use theses as bones in a skin modifier on the box, animate the bones, create a physical camera, activate "Enable motion blur" option in the camera, Use Arnold as render engine, hit render.

Hi,

Sorry for the late follow up. This bug was addressed and fixed on December 5. 

Jeordanis Figuereo (Product Designer. EPHERE Inc.)

Great news, thanks!
I'm waiting for the next update to download, may you have a Happy New Year Celebration!

The fix has been up for some time now. Try the latest nightly build and let me know how it goes. 

Jeordanis Figuereo (Product Designer. EPHERE Inc.)

Sorry for the late reply,
Thanks for the news but the bug still occurs with the last nightly build installed

Hello,

Maybe is not the same bug reported by another user. Can you prepare a minimal scene where the issue is still reproducible? 

Recently we had a bug where hair roots distribution will change when rendering in Arnold with motion blur, which seems to be the same case here. This was fixed on version 8 beta of Ornatrix and recently on version 7 as well. I just tried the scene that the user provided with the latest nightly build of Ornatrix V7(came a few hours ago) and I can confirm the issue is gone, but maybe you case is slightly different and needs further debugging.

Jeordanis Figuereo (Product Designer. EPHERE Inc.)

This is your scene, right?

 

I increased the strand width to see the hair better but as you can see the motion blur is not causing the roots to be re-distributed anymore. 

Jeordanis Figuereo (Product Designer. EPHERE Inc.)

Thank you!
Indeed, I tested on a totally new scene with the last ornatrix update and the problem disapeared. However it is still occuring in my pro work scene, I guess the issue comes from elsewhere. What mail address can I send you this particular 3D scene for you to investigate the issue?

You can send it to Jeordanis .f (at) Ephere. com. 

Jeordanis Figuereo (Product Designer. EPHERE Inc.)