simulating a rainbow.

[super gnu]

so, i was looking at one the other day and wondered if i could recreate it with vray. the proper way.

so i generated a particle cloud in houdini (35,000,000 particles in a 50m cube, 4mm diameter spheres.... approximately accurate values for rain)

then loaded it as a proxy and duplicated it 10 times to make a larger scene.


water material with dispersion. (abbe 50, couldnt find a correct value for water at ambient temp.. at 35 degreees its 56..)

vray sun behind camera, vray sky, large almost black card beyond rain to simulate dark clouds in distance to allow rainbow to show up..


i basically cant get anything intelligible.

the front face of every drop is reflecting the pure overexposed white of the sun and completely drowning out any internal reflections that would lead to a rainbow.

any colour i do get in the drops is random across the image.

ive got gi disabled and im using fixed aa at 12 subdivs.

needless to say it also renders really slowly.

am i asking the impossible?

p.s. i know i would just cheat it for a real project.. this is just playing.

[Art48]

Haha, looking forward to your conclusions . It'd be nice if it works.

Edit:
Have you tried different camera angles and sun angles? As I understand it it physically works only under certain angles between camera and sun.