Need help solving 3D camera for a low texture shot

Hi everyone! Relatively new to the 3d tracking world and I’m in a bit over my head on a shot for a client that I thought would have been an easy one to figure out.

The idea is to comp in a glow underneath the floating girl’s ribcage but step one is to build out the ribcage and make it track with her body in order to matte the glow underneath it. I’ve had success with all the other shots for this project but this one in particular has no background planes to track off of, so it’s been giving me a time the past few days.

I thought since the camera is moving but she isn’t I could use some planes on her body to solve for camera. But despite the tracks looking pretty solid to me, every time I try to solve I get the error message suggesting to try more layers or a different solver.

I’ve uploaded a link to the shot and my tracking attempts here:

I’ve tried my best but I think this one has officially beat me. Any advice or help would be so so so greatly appreciated!

Thank you in advance!

Hi there,

Unfortunately, with the current algorithm for the 3D solver, there is not a way for Mocha to solve this shot. She’s not totally motionless, and it’s hard to get a BG track, so you can’t really solve for a Mocha camera here I am sorry to say.

What host are you using?

Hey Mary,

Thanks so much for giving it a shot. I guess there’s some consolation in knowing my struggles weren’t unwarranted. Here is all my system/host info:

MacOS Monterey 12.2.1
After Effects 22.2.1
Mocha Pro 2022.5 Version 9.5.1

Are there any alternative tracking approaches you recommend?

Is 3D absolutely necessary for this shot? Are you working with 3D models?

I am unfortunately.

The ribcage I’m using for a matte is a 3D model since the camera is moving so much and the parallax of the space between the ribs moving was difficult to recreate with 2D options. However, the subsurface glow I’m using is all 2D but the necessity for the 3D ribcage has made things tricky.

My thought, as of now, was to potentially parent the ribcage to a normal 2D track and then just hand keyframe the Z rotation and scale of the 3D model to match her body the best I can. But are there maybe any other hacks you think could work?

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Yeah, exactly, can you attach it to a simple null and rotate it? That is exactly the “compromise” I was going to suggest.

Yep, that seems to be doing a decent job. Since I’m using Element 3D to import the model over a solid, it looks like I can also hack together a corner pin track which looks like it’s doing a sort of decent 2.5D track with the ribcage matte.

I’ll keep chugging along with those options. Thanks for the heads up on the camera solve though! Its very helpful to know I’ll need to work on some workarounds rather than trying to force an unsolvable solve.

Yes, it’s always better to find a workaround rather than spin wheels for hours. Happy to help. :slight_smile: