Page MenuHome
Create Task
Maniphest T87626

Holes in hair particles - rendering issue
Closed, DuplicatePublic
Actions

Description

System Information
Operating system: Windows 10
Graphics card: NVIDIA RTX 2080 super

Blender Version
Broken: 2.92.0
Worked: also tried with 2.93

Short description of error
Holes in hair when rendering image or animation. Not in the viewport

Exact steps for others to reproduce the error
create a mesh and parent it to an armature. Weight paint a section of it. Add hair particles (1500) with interpolated children (100) and assign the density to the vertex group. Set clump to 0.7. Add hair dynamics and collision to mesh. If I start render I see these holes appear. Every frame they change number, shape and position on the hair and sometimes don't appear on the first frame of the animation. See images below.

Test File:

hair holes.blend20 MBDownload

Related Objects

Event Timeline

Cesare Mangiocavallo (cesaremangio) created this task.Apr 19 2021, 1:56 PM
Philipp Oeser (lichtwerk) changed the task status from Needs Triage to Needs Information from User.Apr 19 2021, 2:23 PM
Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).

Mind sharing an example .blend file where this happens?

Cesare Mangiocavallo (cesaremangio) added a comment.Apr 19 2021, 3:54 PM

hair holes.blend20 MBDownload

Thanks

Cesare Mangiocavallo (cesaremangio) added a comment.Apr 20 2021, 9:07 AM

If I delete all animation keyframes and the armature those holes don't show up in the final render.

Pratik Borhade (PratikPB2123) updated the task description. (Show Details)Apr 22 2021, 1:33 PM
Germano Cavalcante (mano-wii) added a subscriber: Germano Cavalcante (mano-wii).May 6 2021, 9:37 PM

It must be a problem seen only in Cycles because I rendered using the workbench and could not reproduce it.

issue0000-0020.mkv101 KBDownload

Btw, the scenario described is too time consuming for us to track down, we require the bug reporter to narrow down the problem.
Normally .blend files can be simplified by removing most objects and disabling settings, until the problem reveals itself more clearly.

Cesare Mangiocavallo (cesaremangio) added a comment.May 8 2021, 10:33 PM

Yes, the problem exists only rendering with cycles. I'm sure it is related to the animation, hair dynamics and children (simple and interpolated).

Philipp Oeser (lichtwerk) changed the task status from Needs Information from User to Needs Triage.May 21 2021, 1:58 PM
Germano Cavalcante (mano-wii) mentioned this in T95305: Hair with dynamics and motion blur flickers on Cycles GPU render.Jan 31 2022, 4:52 PM
Omar Emara (OmarSquircleArt) changed the task status from Needs Triage to Needs Information from User.Feb 24 2022, 11:37 AM
Omar Emara (OmarSquircleArt) added a subscriber: Omar Emara (OmarSquircleArt).

Does the issue happen even with motion blur off? We have had similar reports related to motion blur and hair.
And does it only happen with GPU rendering or does it also happen when doing CPU rendering?

Germano Cavalcante (mano-wii) added a comment.Mar 18 2022, 7:45 PM

I'll consider this to be the same problem as T95305, as it apparently only occurs with Cycles and GPU.
So I'll merge the reports

Germano Cavalcante (mano-wii) closed this task as a duplicate of T95305: Hair with dynamics and motion blur flickers on Cycles GPU render.Mar 18 2022, 7:45 PM