Compositing Emission onto Video

Hi guys, I’m working on a vfx shot and am a little stumped as to how I composite the emission of an object into video footage… I understand the shadow catcher a little better now (though took me a while), but after playing around, plugging the emission pass into various things, searching online, I can’t figure out how to add the emission to the shot?.. See pics, the red glow is what I want to incorporate into shot. Thanks for any help!



This may not work for every case, but for this example it should be ok:

Add a plane below the object to catch the light, give a white or light gray diffuse shader. Remove every light source in the scene besides your wires. No other lamps, set world color to black, etc. Render out the diffuse direct and color passes. Multiply those two passes together, then add(as in, the blend mode) the result to your shot.

Thanks for the reply, I’ll give that a go… I did find another intermediate solution that worked for my situation… I changed the material to glossy (increased the roughness a bit) then removed all light sources and changed the world background to black so the glossy material reflects pure black. Then I rendered out that scene and used ‘screen’ blend mode in after effects to remove all black from the reflection render, it was quick and rough but worked great for my situation. But I would like to learn how to composite that in Blender!!! Using this method I also blocked out some other basic geometry to get some light emission/reflection in other parts of the scene.