Cycles - Motion blur seems to be additive when rendering animations
Closed, ResolvedPublic

Description

System Information
Windows 7 x64, Ubuntu 17.04

Blender Version
Broken: d53093953f8

Short description of error
Motion blur seems to be additive when rendering animations, rather than only taking the movement for that frame

Exact steps for others to reproduce the error

  1. Open attached blend file
  2. Render to directory
  3. Notice how frames 4 and 5 have motion blur on it, when it shouldnt have any motion blur

This is visible both on CUDA and CPU based renders aswell

Seems like this is a duplicate of T55106

It only has the bug when the position is 'Center on Frame', the other two options avoid this bug.

using a value higher than 1 when the position isnt Center on Frame, reproduces this bug aswell

I can confirm this is happening both on master and blender2.8

Can I please get a developer response? This is quite a major bug for animation purposes.

I have a solution that fixes this but I am still trying to see why it works, but the problem seems to stem from a change in blender_camera.cpp in BlenderSync::sync_camera_motion

Philipp Oeser (lichtwerk) triaged this task as Confirmed priority.Fri, Jun 29, 1:47 PM