Seems like glossy reflection fireflies are still an issue after all these years? I’m getting some crazy ones testing a scene right now with some pretty glossy metal. Unfortunately in VRay Next some renders settings that helped this issue like sub pixel clamping seem to have been removed. I turned down Max Ray Intensity to 1 even, still got them. It’d be nice to keep the reflections if the fire in the metal if possible. Any tips? Using Max 2021.3, VRay 5 hotvix 2, and Phoenix 4.3.01
Increase Min Sampling. Try a softer Image Filter (like Soften at 2px-4.5px).
Try the denoiser (especially the post process one for animations).
Not sure, but you may still be able to enable subpixel mapping by typing this in the Listener Window:
renderers.current.colorMapping_subpixel=true
renderers.current.colorMapping_clampOutput=true
renderers.current.colorMapping_clampLevel=3.0
Set the clamp level t whatever you need.
No idea if that works. I haven’t tried it. It will set the property for your file, which you will then not know if it is set or not should you do anything else with this scene file. Not sure, but it might also get cleared if you switch renderers. You can always just type:
renderers.current.colorMapping_subpixel
renderers.current.colorMapping_clampOutput
renderers.current.colorMapping_clampLevel
And it will tell you if it is on or off. (True or False)
( This is where Chaos will come along and say, “Don’t use hidden maxscript properties,” and I will again say, “Don’t remove features… ever.” 8) No matter how incorrect or useless you think a feature is, somebody probably needs it for something.)
Let us know if you figure it out.
Ah, and one more thing - make sure to use a Phoenix nightly after 21 November - I did a change exactly to Phoenix fire lights and glossy reflections.
Cheers!
Oh, that sounds cool! What sort of change did you make?
The actual fire lights were showing up in the reflections, so made them invisible in specular…
I tried that subpixel script, no effect, I am using the nightly build 2020112630464…i’ll try the latest latest one on there …
Tried the latest build, same thing going on, if not worse.. still have fireflies everywhere, could it be a crazy value of the fire?
Does it help if you reduce the Max Ray Intensity in the V-Ray settings?
Is it possible to send us the scene along with a Phoenix cache file so we can check what is going on?
You can either attach it here as a zip, add a g-drive link or something similar or if the scene is confidential you can send it to the chaos support mail with a link to this thread.
Thanks!
Yeah, Max Ray Intensity still no effect 
Ok lets see if this link works…it’s just a fun side project so I’m fine sharing it. I’m sure it’s something dumb I did… Microsoft OneDrive
Thanks for the scene, on it ! Will update the thread when we know more 
Perhaps try the update script above (I changed the original posting). Not sure that enables the subpixel clamping or not.
Well, now that actually did work! However…my fire is kind of dim and transparent now (some what obviously)…i imagine if i could set a value too that would help. But yeah not exactly an ideal workaround there…
Just sorta weird that Max Ray Itensity doesn’t seem to solve this problem…
I updated that posting again with the command to set the clamp level (I think).
Thanks Joelaff! That is the answer…too bad they disabled it…pretty lame. I can tune it up and down now. Thanks a ton!
Seems like Phoenix needs to have subpixel clamping feature now
In another thread Vlado mentioned Chaos is working on a solution to the fireflies issue. I just hope it comes soon, especially before they make change that would prevent the old clamping from working.
So hopefully this will all become a non-issue soon.
Let me guess, they can’t just enable it again? 
I think it may be going to interfere with some future features or something.
Though I would have left it in the UI until such time. One of my pet peeves is features being removed from software. There is a good chance someone is using those features even if they are not the ideal or perfect way to do things.
At least it is still accessible for now.
Hey,
Glad that Joelaff’s trick does the job.
The fireflies happen due to how the current implementation of the fire works with glossy surfaces. They will clear eventually even without clamping, but you will need a lot of samples which means longer render times.
We’re working on a fix that should help your case and you won’t need the clamping. It should be in the nightlies in the next few days. I will update the thread when you can test it.