Reply To: Cross-key Lighting From Below, And Compositing
I was able to get it animated in less than a day on my CPU-rendering-only potato workstation at the original resolution (compressed here to a gif to post) by first rendering the 1024 spp base, without emissions, then using that as a background image for an emissions-only animation rendering pass with all the non-emission lighting disabled:
Primary ray emissions are a special case in ray traced rendering because the sample can just directly read the surface emission. So, screen quality indistinguishable from the 1024 spp full render is achievable with 1 spp, allowing the 120 frames to be made very quickly.
Not something that can really be generalized because several things had to align for this to be possible, which is static camera, all animation existing only in an emissive texture, and no bounce lighting from those emissions. But those did apply here, so there you go.
Also, CGCookie should consider adding support for .webp. My first rendering of this animation I was going to post here had 4x the pixels, less noise, and had less than 1/3rd the file size than this gif version.