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# Obscuring and partially obscuring 3D layers as they spin around a globe

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 Obscuring and partially obscuring 3D layers as they spin around a globe on Apr 25, 2018 at 11:32:45 am

Hello All-
I have a comp of a C4D rendered globe which has pin-like graphics attached perpendicularly to its surface in AE (imagine a ball with pins sticking out of it). The problem is that when they spin around the back side of the globe they can still be seen... Because there are many of these pin graphics, my hope is to obscure only the parts of each layer that are currently behind the globe without using track mattes. Is this possible using expressions on a per layer basis?
thanks much,
r

 Re: Obscuring and partially obscuring 3D layers as they spin around a globeon Apr 25, 2018 at 4:42:02 pm

Are these pins rotating in 3D space, attached to the surface of the object with a null? Or are they moving in 2D, tracked onto the globe via the point tracker?

If they're moving in 3D space, you could pretty easily create a solid circular object to occlude these pins, which would then be occluded in turn by the C4D rendered globe.

If they're moving in 2D space, then you may be looking at simply keyframing the opacity.

 Re: Obscuring and partially obscuring 3D layers as they spin around a globeon Apr 26, 2018 at 10:54:01 am

They pins are moving this way:

"Are these pins rotating in 3D space, attached to the surface of the object with a null?"

The issue is when the pins are partially occluded by the globe as the spin around the backside of it. This can be addressed via track matting and the like however there are total of 41 pins that spin over the course of about 2 minutes and suffice it to say I'd prefer not to manage each pin's occlusion individually with track mattes/opacity as this would be time consuming...

What I'm really hoping for is an expression driven solution that partially occludes the base of the pin from the camera's POV as it spins around the globe and then fully occludes the pin as the globes rotation takes it fully behind it. I then want the reverse to happen as it spins around the other side.

Keep in mind that the globe is spinning so when the pins on the edge of it spin around it you will no longer see its base however you will see the head of the pin as it spins around and then eventually not at all as all of it becomes occluded by the globe.

Is there a way to do this on a per layer basis (each pin being an individual layer) in AE?

 Re: Obscuring and partially obscuring 3D layers as they spin around a globeon Apr 26, 2018 at 6:49:54 pm

Are the pins made of 3D layers in Ae?

If so, you could just make the rendered footage a 3D layer in Ae. Position it in Z-space at the origin of the pin system, scale it if necessary, and use Layer > Transform > Auto-orient... Orient To Camera.

This will keep it facing the camera (so we don't reveal that it's a footage card in space), and the layer itself will naturally occlude other layers that pass behind it in Ae's 3D system.

Walter Soyka
Motion Graphics, Widescreen Events, Presentation Design, and Consulting

 Re: Obscuring and partially obscuring 3D layers as they spin around a globeon Apr 26, 2018 at 8:18:20 pm

This is my example from another thread: 11911_pin2ccsphere.rar.zip

You can use that to understand what Walter was suggesting.

Cassius Marques
http://www.zapfilmes.com

 Re: Obscuring and partially obscuring 3D layers as they spin around a globeon Apr 26, 2018 at 11:37:41 pm

If the pins are moving in 3D space, then a 2D layer with a spherical mask placed in the appropriate location will occlude anything moving behind it in 3D space. Or do what Walter suggested.