Caustic effects can be costly to set up and costly (in terms of time) to render. Or at least that’s how the saying goes. Like we have all tried to set up caustic effects for a render and then promptly turned them off and considered adding them in post.
That might change now that GPU renderers such as Redshift can handle caustic effects with ease. They are easy to set up too.
Caustics are an extra rendering calculation for photons that can be reflected, refracted and concentrated. It can add another level of realism to your scene if you are focusing on water, glass or other effects where a caustic would be present.
Concept Artist and Matte Painter Saul Espinosa walks through working with redshift caustic effects and also covers some of the settings, with some tips for a more efficient render. It’s pretty straight forward all it requires you to do is turn on caustic photons on both the objects receiving and the lights emitting and making sure its active scene wide.