Camera LookAt Jitter

Development Cinematics & Media
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1

Hi we have 2 related issues with camera look-at which we first hit in 5.3 (I think) but are still reproducible in 5.7. Please find repro video and uasset attached

2

Steps to Reproduce

  • Create a camera crane and a camera in sequencer
  • Attach the camera to the crane
  • Animate the crane yawing around
  • Issue #1
    • Make the camera “look at” a spawnable
    • Save the sequence
    • Notice the look at target is now invalid
    • (as a workaround we can explicitly add the Actor To Track to sequencer, but I feel like this should be default behaviour, as it is likely to continually trip people up)
  • Issue #2
    • Make the camera “look at” a possessable
    • Scrub outside the active range of the shot
    • Save the sequence
    • Notice the camera look-at motion is now jittery when the sequence is scrubbed
3

Hey there,

Apologies for the delay. For issue #1, when you reference an actor for the aim we gather it as a level reference. Once it’s a spawnable, using the binding from the track in sequencer is correct. Unfortunately, during the conversion process, we don’t yet have a good way to track that dependency to fix up to the new binding reference. But I’ll get that in front of the team.

For issue #2, the jitter happens because of how the evaluation with sequencer’s snap to frame scrubbing. If you turn that off you will get the representation of what you should see in playback during scrubbing.

Dustin

4

Hi Dustin

Thansk for response and chasing #1 with the team!

For issue #2 (scrub jitter) since the issue is intermittent i think there must be a bug rather than it being defiend and intentional behaviour. I can also reproduce the jitter, albiet to a much smaller extent when frame snapping is turned off (see attached video). Regardless, our anim team need to use snap-to-frame scrubbing to ensure they set keys and view the animation on whole frames.

thanks

Luke

5

Yep, I agree. I’ve logged an issue here: https://issues.unrealengine.com/issue/UE-357449. It’ll be a bit before it goes public.

One thing you can do to work around it is make your camera a possessable. I’m not seeing the issue there. There were some changes in 5.6 and 5.7 to handle spawnables validating the pre-animated state recently that might have caused this regression.

Dustin