Glossy reflection fireflies

[japetus]

Seems like Phoenix needs to have subpixel clamping feature now

[Joelaff]

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.

[japetus]

Let me guess, they can't just enable it again?

[Joelaff]

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.

[georgi.zhekov]

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.

[Joelaff]

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.

Excellent! Is this a fix just for Phoenix fire lights, or are you talking about an update to VRay?

Thanks.

[georgi.zhekov]

It will affect how the fire is sampled and the fix will be in Phoenix

[Svetlin.Nikolov]

Yup, the 'fix' is basically related to a new implementation, making the Probabilistic Volumetrics work with the Fully Visible fire opacity mode.

This new implementation makes stuff all over the code work differently, including this setup from this thread as well.

Georgi tested it with the scene and it's much better with the new code, and also using denoiser makes it look even nicer.

It needs some time before it enters the nightlies because it also affects the particle shader which also shares a ton of code with the grid volume rendering, so it needs some love as well...

[Joelaff]

Sounds very promising indeed. Thanks for the hard work, guys.

[Svetlin.Nikolov]

I hope it will be a bit nicer to use after this change enters...

Everyone who's been following the Phoenix volume rendering for the past 7-8 years might have noticed that it used to happen in a completely unrelated way to the rest of the V-Ray stuff, and for some time now we've been bringing it closer to the orthodox way, so hopefully not long from now a person wouldn't have to learn to use V-Ray once, and then having to forget everything and learn how to render volumetrics with V-Ray from the ground up

[Joelaff]

By this do you mean more like a VRayMtl shader rather than the Volume Options for shading? Or how do you mean to make it more similar to VRay?

Sure we be cool if volumes could have reflectivity/specularity. Even Phong/Blinn type highlights would be cool.

I just did a dematerialization type effect for a shot, and it would have been nice to have some highlights. In the past would have done that in Krakatoa, which does offer such highlights, but of course takes a ton of particles to make the "volume."

[Svetlin.Nikolov]

Weeeelll, the changes so far and the ones that are coming are a few orders of magnitude more modest More in the verse of "comply with V-Ray settings that affect hard surfaces, render with no more and no less noise than the rest of the scene", etc. But why not have more fancy stuff as well, once the fundament is stable

[Joelaff]

Sounds like some welcome changes nonetheless.

[japetus]

Wow, great guys! That sounds super promising. I can't wait, and thanks as always on getting back so quickly with such in depth answers. Much appreciated!

[fixeighted]

I also have need of the now discontinued clamp feature for something current (It was making me doubt my sanity as I could no longer find it).
It may be incorrect, it may fuck with whatever else in my scene but it worked and I would very much like the opportunity to make a qualitative decision based on my needs please
So +1 for some sort of reintroduction of this until something better comes along to deal with this ever-present headache. I would rather not mess with a possibly working/not working script (thanks Joelaff anyway).