Luma Matte in 3D precomps - I can't make it work

[TORM3NTO]

Hi everyone,

I have animated an infographic and at the very end, I make the camera dolly into a circle (part of the infographics) that I then want to reveal live-action footage. Now, the animated graphics are are 3D layers inside a 3D pre-comp and the background is also made up of 3D layers inside a 3D pre-comp. For some reason, when I try to make a luma matte of the circle, it doesn't punch a hole through the BG, it just disappears. Am I doing something wrong? 

[Mylenium]

Withoutr any details about the timeline structure nobody can tell you much. Could be that you need to duplicate the ring layer, could be that you need to re-order stuff and then of course it simply could be that you would need to pre-compose the 3D layers separately and create the matte in 2D based on the baked-in motion of the pre-comps, including possibly linking cameras across comps.

Mylenium

[Rick Gerard]

My first guess, you are trying to use the C4D rendering engine or 2D layers as track mattes. If you want a track matte to work on a 3D layer then both layers should be 3D and they should be in the same position. You can achieve that by selecting the track matte layer, hold down the shift key, then parent the track matte layer to the target layer.

Another option might be to shift + parent the matte layer to the layer you want to poke a hole in, then apply Set-Matte to the 3D layer and choose the track matte as the source. 

 

Track mattes and effects do not work on 3D layers using the C4D rendering engine. There is a complex workaround, but it is generally not done.