(Resolved) Volume reflection artifacts

[david.anastacio]

Hi,

We're running into a big issue here rendering volumes. Every reflective surface with a glossiness value other than 1.0 that reflects a volume with fire emission is geting this circular artifacts. This artifacts come from the "Emission" in the fire and they apear to be the light grid used on the volume.
Disabling the Emission to get around the isue is not a solution too, as surfaces that also have a diffuse component will have a lot more noise.
Can you make this light grid spheres invisible to specular and reflections please? There is some urgency to this as we have a deadline coming very soon, and all our renders are coming out with artifacts.

Volume reflecting on ground with a 1.0 glossiness:


Volume reflecting on ground with a 0.95 glossiness:


Volume reflecting on ground with a 0.7 glossiness:


Volume reflecting on ground with a 0.95 glossiness and diffuse added to the ground plane. Fire Emission is ON.


Volume reflecting on ground with a 0.95 glossiness and diffuse added to the ground plane. Fire Emission is OFF.



Best,
David.

[david.anastacio]

Example scene attached.

[david.anastacio]

Gosho.Genchev and Svetlin.Nikolov , anything on this issue, we would really love to get a fix on it soon please.

Best,
David.

[Svetlin.Nikolov]

Ah, good thing you tagged me. Just disable the fire lights and let the gi do the illumination by the fire.

Cheers!

[david.anastacio]

Ah, good thing you tagged me. Just disable the fire lights and let the gi do the illumination by the fire.

Cheers!

Hey

I did that in my last example image.

Volume reflecting on ground with a 0.95 glossiness and diffuse added to the ground plane. Fire Emission is OFF.


This becomes quite slow to render, as now the GI has to do all the work.
I think we all agree they should not be there, the light grid should emulate only diffuse lighting, and I imagine the solution is quite simple, the Fire Emission grid lights should be invisible to Reflections and Specular. Is this possible?

Best,
David.

[Svetlin.Nikolov]

Hey,

Sorry, I misunderstood that you have already tried turning the fire lights off. Seems like in the Houdini GUI the option is named differently than in Max and Maya.

So yeah, making the fire lights NOT affect specular does work, but we need to figure out if there is a valid scenario when someone would need specular with the fire lights.

Will ping you when we change it. Which V-Ray version do you use? Maybe this would need to be backported into V-Ray 4 as well?

Cheers!

[david.anastacio]

So yeah, making the fire lights NOT affect specular does work, but we need to figure out if there is a valid scenario when someone would need specular with the fire lights.
Cheers!

Not sure I would ever use the grid for specular, it's a grid, even were cranking up the grid resolution it's still a grid so the result will still look a bit strange.

Which V-Ray version do you use? Maybe this would need to be backported into V-Ray 4 as well?
Cheers!

Vray 4 yes.

No VRay 5 in prodiction here

Best,
David.

[Svetlin.Nikolov]

Alrighty, so in tomorrow's V-Ray 4 and 5 nightlies, the fire lights will not affect the specular by default.

In Phoenix and V-Ray for Max and Maya I also added a hidden script option named 'firelightsspec' that would allow re-enabling this if anyone needs it - if this option is needed for other hosts, it can be added as well.

Please ping us when you manage to check it.

Cheers!

[david.anastacio]

Svetlin.Nikolov that's is great news, this is higly appreciated, will give you feedback tomorrow as soon as I get my hands on the new build. Thank you!

Best,
David.

[david.anastacio]

Hi Svetlin.Nikolov, Just tested the new build and unfortunatly the reflection issues still perssist.



Using tonight's build.

Best,
David.

[Svetlin.Nikolov]

Indeed, looks like the nightly does not have my changes. The vray_phxshader.dll is 2 weeks old. Will ask my colleagues...

[Svetlin.Nikolov]

Yup, there were some build issues that prevented appsdk to be updated, will ping you again...

[david.anastacio]

Yup, there were some build issues that prevented appsdk to be updated, will ping you again...

Thanks for the update

[Svetlin.Nikolov]

Yess, so the changes are in these nightlies: https://nightlies.chaosgroup.com/mai...ghtly/20201125

If anything pops up, please ping me

[david.anastacio]

Yess, so the changes are in these nightlies: https://nightlies.chaosgroup.com/mai...ghtly/20201125

If anything pops up, please ping me

All good now
Thanks for the effort and quick turn around Svetlin.Nikolov, the team here really appreciates it.

Best,
David.