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Animation and motion graphics

Blender / Cycles / Particles / Motion blur artefact fix

By March 31, 20174 Comments

A render with lots of particles (baked), using Blender and Cycles. I was getting this peculiar streak artefact right next to the particle emitter:

After a bit of fiddling around, I’ve sussed what’s causing it. The default setting for Motion Blur in Cycles is to centre the motion blur around the frame time: it opens the “shutter” before the frame time, then closes it after the frame time.

So when it’s rendering frame 7 with a half-frame (180°) shutter, it’ll actually render the portion of time from 6.75 to 7.25. But it seems that when Cycles reads the particle data from the cache, it only reads the previous frame and the current frame. So the second half of the motion-blurred period doesn’t have the correct particle data to work from.

Easy fix then: choose either Start on Frame or End on Frame instead. Which one to choose will depend on your scene, but it should become obvious when you test it.

Streak artefacts gone! (Phew)


  • Dear Howard,

    I just saw a video from James Hood and I am so in love with the graphics. Did** you do those??

    I am a composer for film and games and always experimenting. I would love to work with you – if I got the right** man. Let me know – and thank you for your time …

  • Zheng Lv says:

    This is what I’m searching for. Thanks for solving my problem.

  • Mike says:

    This has been driving me crazy for two days – I tried tweaking every option in my particle and wind settings, but nothing was working. Thanks for the quick and easy solution – worked like a charm!!

  • Owen says:

    Hey. It’s been 2.5 years, but if you want the solution, bake the particles into cache, and turn up the steps in between frames to something like 10

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