Motion blur ghosting - related to temporal sample AA

Development Rendering
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1

I try to render a sequence with movie render queue. There is a car which move forward in the scene.

Rendering settings:
None antialiasing, sample 2, temporal 32
Motion blur on cine camera 0.1

I’ve attached two video about the ghosting (look at the license plate)

  • If I do not override anti aliasing in movie render queue, then there is no ghost
  • If I disable motion blur then there is no ghost
  • If I set motion blur amount to 1.0, then there is no ghost what I don’t really understand why. (I’ve attached a video about it)

Blur amount in cine camera (0.1):

Blur amount 1.0:

So is it a bug, or is it expected?

Képernyőkép 2024-06-13 113339
Képernyőkép 2024-06-13 113339670×568 31.2 KB

2

Hi there @bdezso,

Hope you’re well!

This topic has been moved from Community: Showcase to Rendering.

When posting, please review the categories to ensure your topic is posted in the most relevant space.

Thanks and happy developing!

3

not a bug, that combination does exactly this. motion blur amount is shutter openness: at 1.0 the shutter is fully open across the frame so the 32 temporal subframes blend into one smooth streak, at 0.1 each subframe is nearly frozen and spread across time, so you see the discrete steps as ghosts on teh plate.

rule of thumb: blur amount and temporal count are one tradeoff, not two knobs. high temporal (16-32) wants blur near 1.0, low blur wants temporal down at 2-4. with AA method None plus override you are also working without any accumulation filter, so every step shows. try temporal 8 with blur 1.0 as a baseline and compare.

temporal samples and what they do to moving detail in MRQ are covered here: Plates and Matte Paintings in Unreal Engine