Guided "Dynamic" Spline Animaton

[seunyboi]

Example video below:

https://drive.google.com/file/d/1M7FgWmEj6YZz4qG52Jq4UX3iEPKtI5h9/view?usp=sharing

I have a project where I need to animate a coil object like this so that when it deploys it conforms to a predetermined shape. It doesn't seem like C4D's spline wrap animation can achieve this kind of a result because of how it moves the source object through the spline. I need some kind of a technique that dynamically deploys the "spline object" but adheres to a fixed shape. I'm assuming it needs to be dynamic, but open to other solutions.

Thanks,

Seun

[Dr. Sassi]

Hi Seun,

This would be the simplest version I can think of, and I have tested it for most of the afternoon.
CV4_2024_drs_24_ANca_01.c4d

Yes, it is different…

I can't really see dynamic as the solution here, especially when the setup is rotated internally to draw four circles like on a "tetra" geometry in a sequence.

If that dynamic aesthetic is key, the larger Tracer> Sample Step amount and the B-spline might help here.

I believe that you have a different idea. Can you share the Coil object as a simple dummy and perhaps some more details about how it should move? Do you have a storyboard, perhaps?

Cheers

[seunyboi]

@Dr-Sassi

Hello Dr. Sassi,

Thank you for responding and putting together this example project. I think what you have is a possible way of executing this, but I think the unique thing about the animation is that it's supposed to feel like the coil is being fed through a tube from the proximal end so it it bunches up in the sphere. So the distal tip of the coil does not continuously moving along the entire spline path. Does that makes sense? Ha

Here's a very old video that demonstrates the same motion: https://youtu.be/qcVdsLEqYqI?si=PBZ7_Y1yUU1VHVWJ&t=35

I've attached a example project with a dummy shape of coil.

3.5mm X6.c4d

I have CAD for the coil in it's final Tetra shape, but since it's a pretty simple model, my plan was to remodel it so it's uncoiled and completely straight to it's 6cm length, and then spline wrap it to the final spline animation/sim. I just need to figure out how to animate the spline like the reference videos.

Seun

[seunyboi]

This might also help: Here's the product page for the coil: https://www.stryker.com/us/en/neurovascular/products/target-tetra.html

You can see that the model isn't very complex, just the shape. And there's a sample video of it being used in real life at the bottom of the page. Clinically, it won't actually take on the tetra shape when it's deployed, it's close, but it ends up looking kind of random. But for the sake of animation, I'll need it to look like the tetra shape.

Hopefully that helps illustrate it needing to feel less like a snake moving along a path and more like it's a rigid wire being fed through a tube into a tight space.

[Dr. Sassi]

Hi Seun,

I explored a few of those animations. The Spiral/Coil formation seems in the minority on YouTube. It looks to me more often like a random filling of that spherical space, like this one here, cached in Cinema 4D.
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2024_PROJECTS_DRS/20240521_CV4_2024_drs_24_ANva_02.c4d.zip
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This would be a complete simulation-based option.

The other way to get a precise helix in a tetra formation is to use full animation, like this one.
CV4_2024_drs_24_ANva_13.c4d
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Is there anything that comes closer to your target?

All the best

[seunyboi]

Hello Dr. Sassi,

I agree, I feel like the random filling would be the best route.

I'm assuming on the first scene, you just created a long spline, tweaked some parameters, and let gravity pull it down into the sphere? I think that's probably the route I'd go for this animation. I guess now I'm just wondering if there's a way to get the same effect, without needing gravity as the force to pull the spline. Again, thanks for helping me troubleshoot this! This is very helpful.

Seun

[Dr. Sassi]

Hi Seun,

Please have a look at the file below.
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2024_PROJECTS_DRS/20240522_CV4_2024_drs_24_ANva_21.c4d.zip
(Scene is cached)

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I have added some ideas, which may lead to some adjustments on your side, but I hope it brings it closer to your target.

Please note that I have set the scene-wide Gravity to zero but introduced the Gravity Force to direct the progress.

My best wishes for your project.