Rendering movie with alpha background

I’ve been doing matchmoving and I want to be able to render the animation without the original video background. This way i can render it with a transparent background and do color correction in after effects with the blender render over the original film. How is this accomplished?

I haven’t used alpha layers in After Effects, at all, so this may sound goofy.

But couldn’t you render out an alpha layer in blender and then use that alpha layer as a mask in AE?

Might also look at the AE exporter in Blender?

Anybody else have an idea?

I don’t think you can render without a background. You can render with an alpha layer with the background portion set to transparent. Typical work flow is to render to an image sequence that supports alpha layer info, i.e. .png. You can also render to Quicktime with alpha info, however you risk issues with failures particularly on long render times. There all kinds of posts here about why it is best to render an image sequence. If you must have a movie for input (I imagine that AE supports image strips) you can always use the VSE to render the image sequence to a video file, but your format must support alpha channel, e.g. Quicktime.

I’m not quite sure how to approach your question, but there are two things to watch for:

  • You must request the Alpha channel’s presence by being sure that the RGBA button is pressed.
  • You must output to a file-format that actually supports an Alpha channel.

I already render .png files. And I was asking if about alpha/no background. same thing. What I was asking was how to set it to render alpha for background within blender