Its about spot light lamps in combination with Cycles Glossy and Glas Shaders. In this post i only make use of unchanged shaders "Glossy BSDF" and "Glass BSDF" from cycles.
The blend file is here: http://pasteall.org/blend/index.php?id=47499
And what i am trying to do is a simple Cycles setup using a camera, a flat cube and a spot light:
- The Spotlight has Strength 300 with a spot shape size of 20 degree
- The cube material uses Glass BSDF (Beckmann) with roughness 0.1 and IOR 1.45
- The camera looks straight downwards
- All items are aligned on the Z axis
This is the render result with 128 samples after about 15 seconds:
The downside here is that now the image renders in 2 minutes and actually the spot is not so much "spotty" but more "cloudy"
Someone told me that increasing the lamp size will fix it. So i increased the lamp size from 0.2 to 1.0 and the flies are gone but the spot is again cloudy.
Ok, lets make a break here. Actually i am not even interested in the reflection on the glas surface (for now). I rather want to get the spot light passing the glass and travel further down to another flat cube that uses a glossy material (a mirror actually).
I change the setup a bit as follows:
So i now expect to see the reflection of the light spot on the lower plane, and indeed the spot is there, on the left side i see the reflection from the glas and on the right side i see the reflection from the lower plane (the mirror:
but ... fireflies are back :( Now i need some help out of this :) thanks for any hint!