How to create “glowing eyes” effect on a video imported as an image plane

Question

Hypothetically, I have a pre-keyed video of a stop motion animated character I created with help from my compositor of choice that I’ve added to my 3D landscape as an image plane. A key component to his look is his glowing yellow eyes for realism’s sake, an addition that is fairly easy for me to do in the compositor but not so much in Blender.

I really hate the thought of having to go back and forth between two programs to achieve the effect, so I was wondering if any of you know of a way of pulling it off within Blender.

Answer 1

If I understand you correctly, you want the eyes seperate in blender so they can cast light and interact realistically with the scene. You already have them in your compositor, and want

If that's the case, export your eyes to a seperate file (with only the eyes) or an unused channel in your stop motion (like the alpha channel if you aren't using it) then use thatto mix with a bright emission shader in the material editor.

Answer 2

Recreating a digital copy of the eyes, adding an emissive texture, then motion-tracking the eyes and their orientation to the footage is the only way I can think of. It's a fairly complicated (IMO), but do-able process.

The best source of this that I've found for free is by CG-Matters (https://www.youtube.com/watch?v=WLSGG7sDEac&t=2225s). Ian Hubert also has some videos, but this guide is a little slower and easier to follow along with.

You could also rotoscope them in, but consistency between frames becomes a little bit more difficult. It really depends on how long the animation is; and your capacity to do something the complicated way or try to brute force it.