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Maniphest T54284

Blender Cycles Render make weird scratches on surface of objects when it's following path
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Description

System Information
My laptop:
GeForce GTX 1060 6gb with Max-Q Design
16 GB RAM
i7-7700HQ CPU @ 2.80GHz
Windows 10 (x64)

and also other PC with similar set up, the differences:
32 GB Ram,
GeForce GTX 1070 TI

Blender Version
2.79a Hash: 8928d99270f, Date: 2018-02-21 (but in just 2.79 was the same problem)

Short description of error
When pieces of a car parrented to an Empty Cube (called: "CAR") are moving (because of the Empty Cube movement by Follow Path Constrain), after frame 328 it is starting to makes weird scratches on the surface of the objects. Regardless of Motion Blur, Material Settings, World Settings, Modifiers... But when you disable the Follow Path Constrain on the Empty Cube the scratches are gone.

The very extreme sctraches are visable after frame 420.

glitch.blend1000 KBDownload

Exact steps for others to reproduce the error
Just turn on rendering, even in viewport

Related Objects

Event Timeline

Łukasz Debita (evilferber) created this task.Mar 10 2018, 8:41 AM
Łukasz Debita (evilferber) updated the task description. (Show Details)Mar 10 2018, 8:44 AM
Philip Holzmann (Foaly) added a subscriber: Philip Holzmann (Foaly).Mar 11 2018, 4:31 PM

I can reproduce this.

I have simplified the scene.

glitch.blend615 KBDownload

Go into rendered preview. There is a black stripe on the bottom left corner of the object.
The stripe seems to get thicker the further the object is away from the origin. However the numbers seem to small for it to be a floating point inaccuracy.
The effect also gets stronger, when the Bounces Max is decreased.

Brecht Van Lommel (brecht) changed the task status from Unknown Status to Unknown Status.Mar 15 2018, 2:48 AM
Brecht Van Lommel (brecht) claimed this task.
Brecht Van Lommel (brecht) added a subscriber: Brecht Van Lommel (brecht).

Thanks for the report, this appears to be another variation of a known issue that we are trying to address in D1212 for example. Small features far away from the original are problematic for raytracing.

Brecht Van Lommel (brecht) closed this task as a duplicate of T43835: ray offsetting giving precission problems / render artifacts / cracks on far away geometry.Mar 15 2018, 2:50 AM
Ha Hyung-jin (robobeg) mentioned this in D6250: Fix T43835, T54284: Cycles with no ray offsetting.Nov 13 2019, 6:08 PM
Jesse Yurkovich (deadpin) mentioned this in T94056: new cycles shading artefacts in todays build.Dec 14 2021, 12:54 PM