Caustics + Physical Sun and Sky problem

#1

Hello everyone

currently i work on a simple pool. i set up a normal physical sun and sky environment with an mia_exposure_photographic lensshader. so far so good, all works fine.

i rendered my stuff and the water looks oke, i can see to the ground, i can see differences between deeper and less deper areas on the pool and so on.

now my problem: when i activate the caustics in the rendersettings, my water gets way darker than before with FG only and i can’t see on the ground of the pool. i looks like no light goes through the surface.

how it looks without “caustics on” in rendersettings:

and when i a activate the caustics in the rendersettings:

i used a mia_mat_x to create the water shader and set a max distance for the refractions. the really strange thing is, that i activated the caustics, but they are no lights which are emit photons and so they should be no effect, right?

so can anyone help me? i have no idea how to fix that prob :S

here is my shader setup:

Cheers,
Marco

#2

Hi Marco,

When you activate the “refractive caustic” option in mia_material and caustics in the render settings window shadows lose their trasparency and become black. That’s why your water is darker. Photons, once shot, should take care of bringing back the trasparency of shadows. This is by the way more physically accurate than transparent shadows, that are some sort of trick.

Hope that helps.

#3

Hi Paolo

thank you for the answer. now i get good looking renders with caustics and gi set to on.