HDRI reflection hotspots (Firefly issue)

[banaltheory]

Hi,

Is there a proper solution to the firefly issue when rendering with HDRI that has lots of hotspots (ie high values, bright lights at night)?
We tried to use the subpixel mapping and clamp the output to 5 but the artifacts are still quite noticeable.
Clamping lower than that seems to defeat the purpose of the flexibility in post.

This issue is also applicable to any visible 3d lights with a high intensity value as well. ie. sphere lights.

What exactly is the cause of this issue? is it the interpolation of subpixels between two extreme values?

Scene files, HDRI and quicktime attached.

Vray 2.30.01
Maya 2013
Win7 64 bit

[tashko.zashev]

Hi,

This HDRI file has very small details (bright spots), which requires more reflection samples.

There are few things that could be made in order to avoid/decrease this reflection flickering.
*) Increase the AA settings. (min/max 3/12 ; noise thresh. 0,005)
*) Remove the background Env. and add it on post, in order to render the animation faster.
*) Render to bigger resolution (50%)
*) Replace the Reflection/refraction HDRI with Filtered one (Effects/Filter 5)

Attaching few frames rendered with this setup:
Render.zip
I hope this helps.

Maybe motion blur can be added as well.