Hi guys i just want to share some info on how i aproach the caustic generation using Corona.
The idea came up earlier this week when i was doing a glass over a table.
I know the caustics are quite render expensive but i came with this method and is quite fast.
Get the best of both worlds, realistic caustics from an experimental "incomplete" Bidir/VCM and the awesome beauty pass of Corona Progresive/bucket.
The plus?
You can do Caustics + dispersion using what corona gives you and quite fast.
The idea is to get something like this:

So here it is the max file, the images needed a pdf explaining (the best i can) the method and a couple of photoshop files showing the compositing part.
It came up so well that it can be used to do animated caustics very fast and very accurate.