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I've done a quick 3D track in blender and I'm trying to render my output, but the plate I used to track is showing up over my 3d objects.

I want to render the objects in the scene with an alpha channel and comp them over the plate I tracked. My renders however, are covered by the aforementioned plate.

Un-checking "Background Images" in the camera properties (only removes it from the viewport) isn't doing it for my render outputs.

Working on some production tests and am not really proficient with the software yet, my apologies in advance.

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  • $\begingroup$ Do you have anything in the VSE? $\endgroup$
    – dval
    Commented Jan 17, 2016 at 6:14

1 Answer 1

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Using the compositor, the most basic setup to combine a 3D scene with an image (still or a video file) is mixing the movie clip and the render layers using an Alpha Over node.

The node sockets to which the images are connected determines the result:

The background image should be connected to the top socket

The foreground image or scene to the bottom socket.

enter image description here

The foreground's alpha channel is used to overlay the foreground on to the background.

enter image description here

If both images had an alpha channel, both alphas are combined for the final image.

enter image description here

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  • $\begingroup$ Hey, Thanks for the reply. It's fantastic to know this could all be handled inside the software. I'd actually just like the frames so i could do the compositing in nuke. $\endgroup$
    – TheDude
    Commented Sep 10, 2015 at 17:04
  • $\begingroup$ It seems like blender is already outputting a rendered comp. I set the output formate to exr, and shuffled out the background pass in nuke, giving me the result i wanted.Will continue messing around.... $\endgroup$
    – TheDude
    Commented Sep 10, 2015 at 19:44

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