Lighting Sprites - Will they go away?

[nick888]

Hello,

I am trying to simulate an actual light, with a spotlight source transmitting through a transparent plastic lens, glass and then out into the environment. I get that it's a bit of an ask perhaps for KeyShot.

In certain circumstances it seems to work OK, but in this particular scene we have a level of noise / sprites that remain in the plastic lens material that never seem to go away. I'm talking about many (5+) hours on a 3970X.

I've tried with/without Global Illumination - obviously caustics is key to actually getting the effect we want here, also Product Mode / Interior mode seem similar.

Any tips would be appreciated!

Thanks

[KristofDeHulsters]

Did you use the firefly filter? That's most likely what you're missing because you have two transparent materials, a complex shape and a light source closely together. This is what I got in 5 minutes, I would probably turn the firefly filter down a bit to make sure I get some more detail.

[nick888]

Thanks for that.

I assume you mean the Denoise filter?

I had been working with that, but it didn't really produce an effect I liked - perhaps I just needed to play with the blending a bit more.

Was also interested to know if there was anything fundamental I could modify (material types, lighting settings etc) but I guess it's just the nature of the scene as you say.

[KristofDeHulsters]

Keyshot 10 has a firefly filter under the denoise tab. I am assuming you are using an older Keyshot version then (which doesn't have this yet).

The fireflies are really caused because the lights in your scene emits rays which are calculated and every calculation that ends up going straight into the camera becomes a firefly. When you have a light source really close to geometry it tends to shoot out a lot of fireflies because there are so many rays bouncing out of the light straight into a material with some reflectivity. Denoise mainly pixels becoming the wrong color because of the sample count not being high enough. No high sample count will resolve fireflies.

If you don't want to upgrade to K10, I would recommend rendering the scenes out with all the passes and try to use the diffuse pass to patch up the fireflies in PS. Using the clone tool in PS might also work if you have only a small amount of fireflies. Either way, without the firefly filter, you will have to do some PS-adjustments.

Hope this helps!

[nick888]

I do have Keyshot 10, I had just not noticed / realised the Firefly filter was there!

Thanks for your responses & explanations - very helpful!

[KristofDeHulsters]

No problem! Glad I could help you solve the issue!