Possible Solution to the Firefly problem

[Jaberwocky]

Looking in detail at the firefly problem we've been having for years ...i might have a solution for you all to try......sort of a workaround.

Try this on an interior shot with daylight settings with plenty of reflective surfaces as an example.

Render one shot until it's clear except for the fireflies, (which tend to stick around forever, even running quad titan blacks )...... Use a sun size of less than 1

Render the same shot again but with the sun size set to 30.

You now have two shots of the scene, both with Fireflies , but with the crucial difference that the fireflies in each shot are in different positions to the other render.

Put both shots into two layers in Photoshop and set the blend mode to Darken.

Because fireflies are white and the corresponding pixels on the other layer are darker, the firefly pixels are substituted for the correct ones.

merge down the two layers and hey presto.. a clear scene.

This is why it's essential that the fireflies appear in different positions in each render.

If your using HDRI or interior lights you may need to adjust the scene lighting in each of the two shots in someway to accomplish the same outcome.

Hope this helps you all.

Jaba

[prodviz]

Really nice idea.

I guess the addition of the GI control in version 2.04 will help with fireflies too.

cheers.

[Jaberwocky]

Possibly, although i'm still using 1.55 standalone for now.

One thing to add.Because the darken Blend mode in Photoshop may take out some of the light reflections in the scene, i would suggest adding a layer mask on the underlying layer to let back some of the light reflections in the original scene.