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Jitter/judder problem with motion tracking a panning camera
Posted: 12 August 2019 09:27 PM   [ Ignore ]  
Total Posts:  25
Joined  2012-02-21

I unfortunately can’t supply a scene file, so I’ll try my best to describe what’s happening. I was given a piece of footage where the camera pans to the right while affixed to a tripod. Because of that, I had to set the Solve Mode to Nodal Pan when I motion tracked the scene. I placed my stationary 3D object into the scene and everything looks fine.

However, when I render the scene (everything including the original footage is set to 24 fps) and composite it in After Effects, I get a noticeable jitter effect, which I’ve learned is maybe called judder in this scenario.

One forum post on another site said the three options to fix it are to slow down the camera movement, increase the frame rate of my project, or increase the shutter angle. I can’t do the first option, and I’m not sure how the second option would solve it, but I tried the third option overnight last night - increasing the shutter angle from 180 to 360. That didn’t seem to fix anything at all.

The part that confuses me the most is that the 3D object moves along with the footage perfectly fine when viewed in C4D. But when they’re brought together in AE, the footage is still smooth while the render is jittery. Is there something obvious I’m overlooking? Thanks for any help.

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Posted: 12 August 2019 11:14 PM   [ Ignore ]   [ # 1 ]  
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Hi intaglio,

I have sent you an upload link, I will not post the file in public. Please just a compressed version, no raw or UHD version, thanks.

Pan tracking should be the most stable.

All the best

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004
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Posted: 13 August 2019 02:04 AM   [ Ignore ]   [ # 2 ]  
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Joined  2012-02-21

Thanks for your reply, Dr. Sassi. I think I figured out what was happening. The footage itself IS jittery, but for some reason, I had to shift the C4D-rendered image sequence forward by one frame to have both the footage and the render’s “jitters” line up.

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Posted: 13 August 2019 02:20 AM   [ Ignore ]   [ # 3 ]  
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Thanks for the update, intaglio.

Sounds good, and I’m glad you found it.

Without anything to work with, it would have been an endless questionnaire. Something I try to avoid.

What you found could be the typical discussion:
Is it possible that at any point the starting frame was zero and some other started with frame one?

Often that is in slower motions hidden based on the matching motion blur that needs to be applied to the 3D render to match the footage.
For faster motion, even a frame matched motion might be not enough, and the shutter timing needs to be precisely the same.
Lots of additional question (was the lens-distortion fixed, etc.), and I think it is always best to answer based on the results of material exploration.

If you want to evaluate the speed of the pan, you might want to check out this source, just for future references:
https://www.red.com/red-101/camera-panning-speed
I assume you have the camera/lens data.

Enjoy your project

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004
Maxon Master Trainer, VES, DCS

Photography For C4D Artists: 200 Free Tutorials.
https://www.youtube.com/user/DrSassiLA/playlists

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