Hello!
I’m currently trying to artifically light a short videoclip. I made a 3D camera and rebuild the geometry of the room in blender. I set the geometry pieces to “cast shadows” so that the geometry won’t show up in the render, only the shadows. So far so good.
But what about light? How do I put light on to a plane so that only the light shows up on the videoclip?
Yo may want another setup, where all your materials are white , no other light influence except the one you’re looking for ( get rid of world/ambiant light) , and do a render.
That should give you a black and white image with the light you’re looking for.
This can be done with a material override :
but you should use regular light for lighting , not planes with emission.
Then, you can use this render to light your scene, maybe by using the render to influence a RGBCurve.
All this will work ok if you’re doing subtle changes, but obviously this will not always work, it really depend on the case and the initial videoclip you’re working with.