alembic results in hair with "random position per frame" in render time #60936

New Issue

Daniel Bystedt · 2019-01-28T00:58:58+01:00

Daniel Bystedt commented

2019-01-28 00:58:58 +01:00

System Information
Operating system: windows 10
Graphics card:GTX 1080

Blender Version
Broken: 2.80, 2019-01-26, 25772c9e1d, branch: blender2.7
(example: 2.79b release)
(example: 2.80, edbf15d3c0, blender2.8, 2018-11-28, as found on the splash screen)
Worked: (optional)

Short description of error
hairNoise.rar
When using rendering hair and using alembic as mesh cache (Mesh Sequence Cache modifier) I get unique root positions of each hair strand per frame. This bug can only be seen in rendertime. When looking at the fur in the viewport, everything looks fine.

When using MDD as cache format, this issue can not be seen. Only alembic cache seems to be affected.

Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).

create a sphere
2 add a displacment modifier with cloud texture and animate the displacement. Any deform modifier will do
Export the sphere as alembic
Duplicate the sphere
add a Mesh Sequence Cache modifier and connect it to the exported alembic.
add fur. Use few hairs so it's easier to spot the random hair poisition per frame.
scrub the timeline. Notice that the hair looks fine in the viewport
render the image sequence. Look at the rendered images and see that the fur looks really noisy/jittery per frame

**System Information** Operating system: windows 10 Graphics card:GTX 1080 **Blender Version** Broken: 2.80, 2019-01-26, 25772c9e1d2d, branch: blender2.7 (example: 2.79b release) (example: 2.80, edbf15d3c044, blender2.8, 2018-11-28, as found on the splash screen) Worked: (optional) **Short description of error** [hairNoise.rar](https://archive.blender.org/developer/F6426330/hairNoise.rar) When using rendering hair and using alembic as mesh cache (Mesh Sequence Cache modifier) I get unique root positions of each hair strand per frame. This bug can only be seen in rendertime. When looking at the fur in the viewport, everything looks fine. When using MDD as cache format, this issue can not be seen. Only alembic cache seems to be affected. **Exact steps for others to reproduce the error** Based on the default startup or an attached .blend file (as simple as possible). 1. create a sphere 2 add a displacment modifier with cloud texture and animate the displacement. Any deform modifier will do 3. Export the sphere as alembic 4. Duplicate the sphere 5. add a Mesh Sequence Cache modifier and connect it to the exported alembic. 6. add fur. Use few hairs so it's easier to spot the random hair poisition per frame. 7. scrub the timeline. Notice that the hair looks fine in the viewport 8. render the image sequence. Look at the rendered images and see that the fur looks really noisy/jittery per frame

Daniel Bystedt commented

2019-01-28 00:58:58 +01:00

Added subscriber: @DanielBystedt

Daniel Bystedt changed title from ~~alembic results in hair with "random seed per frame" in render time~~ to alembic results in hair with "random position per frame" in render time

2019-01-28 01:00:50 +01:00

Sebastian Parborg commented

2019-01-29 11:32:37 +01:00

Added subscriber: @ZedDB

Sybren A. Stüvel was assigned by Sebastian Parborg

2019-01-29 11:32:37 +01:00

Sebastian Parborg commented

2019-01-29 11:32:37 +01:00

Just a quick note, I had to change search path for the abc file as it had an absolute filepath with the mdd had a relative one and worked out of the box

Brecht Van Lommel commented

2019-07-03 19:31:12 +02:00

Closed as duplicate of #58704

Brecht Van Lommel closed this issue

2019-07-03 19:31:12 +02:00

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alembic results in hair with "random position per frame" in render time #60936