3dsmax / VrayEnviromentalFog / Beam Lights issues

[akis_kyriakopoulos]

Hello there.

I have been asked to create some beamlights but I'm getting artifacts/or missing parts as you can see in the screenshots.

I'm using 3ds Max 2023 and the most recent Vray version.

Any ideas of why this is happening? I have tried many different things that didn't work. Any help would be greatly appreciated.

Many thanks for considering my request.
Akis

[Joelaff]

IIRC, reduce the step size/threshold, and possibly increase min AA.

But you can save yourself a lot of headaches by using Max Spotlights and Max's Volumetric Light Effects for this type of thing. Much faster. https://help.autodesk.com/view/3DSMA...1-54A0A3CD9D62

[akis_kyriakopoulos]

IIRC, reduce the step size/threshold, and possibly increase min AA.

But you can save yourself a lot of headaches by using Max Spotlights and Max's Volumetric Light Effects for this type of thing. Much faster. https://help.autodesk.com/view/3DSMA...1-54A0A3CD9D62

Hi, and many thanks for the fast response!

Unfortunately, the changes in the suggested settings did not work.

I found a temporary solution using Max Spotlights for this project, as you said, but they don't give the same effect as the Vray ones.

I hope I find the reason behind the Vray fog and lights issue.

[Joelaff]

Sorry it didn't help. I know I have seen this issue before, and I am pretty sure it has been discussed here as well. Maybe it is a scene scale thing, as in a simple test scene I had no problems getting thin beams with default settings. I tired VRay lights, rectangular or disc (Directionality at or near 1.0). I tried Max Spots with VRayVolumeFog as well.

It looks like you may not be on the latest VRay, or you would have a Directionality Strength setting if you were (not that this setting is the answer, but perhaps the newer version is harder to break in this regard, because I have seen this issues before, but now I am having trouble reproducing it).

You could try lowering the Cutoff for the light, especially 0.1 seems very high.

OK, I did just see the issue with decay turned off (or set very far, as there is no longer a No Decay setting). (Edit-- not related to decay it seems) The IPR or Progressive always seemed to resolve it at default settings, but with the bucket renderer I set the Min subdivs (AA) to 2 and it solved it. Increasing Min Shading Rate also solved it (which is weird, I did not realize that would effect things other than reflections/refractions/GI.). Higher Min subdivs was faster to render than the higher Min Shading rate (also interesting).

[hermit.crab]

Increasing the min AA subdivs usually resolves such issues (they are caused by the light ray not managing to hit the light, hence needing more samples). If it doesn't help send the scene so we can troubleshoot.

[akis_kyriakopoulos]

Sorry it didn't help. I know I have seen this issue before, and I am pretty sure it has been discussed here as well. Maybe it is a scene scale thing, as in a simple test scene I had no problems getting thin beams with default settings. I tired VRay lights, rectangular or disc (Directionality at or near 1.0). I tried Max Spots with VRayVolumeFog as well.

It looks like you may not be on the latest VRay, or you would have a Directionality Strength setting if you were (not that this setting is the answer, but perhaps the newer version is harder to break in this regard, because I have seen this issues before, but now I am having trouble reproducing it).

You could try lowering the Cutoff for the light, especially 0.1 seems very high.

OK, I did just see the issue with decay turned off (or set very far, as there is no longer a No Decay setting). (Edit-- not related to decay it seems) The IPR or Progressive always seemed to resolve it at default settings, but with the bucket renderer I set the Min subdivs (AA) to 2 and it solved it. Increasing Min Shading Rate also solved it (which is weird, I did not realize that would effect things other than reflections/refractions/GI.). Higher Min subdivs was faster to render than the higher Min Shading rate (also interesting).

Hi again and thanks a lot for your time. I Appreciate it.

I tried all the above and still nothing works. I have no idea why this is happening but I'll make sure to leave a post here when/if I find the solution to the issue.

[akis_kyriakopoulos]

Increasing the min AA subdivs usually resolves such issues (they are caused by the light ray not managing to hit the light, hence needing more samples). If it doesn't help send the scene so we can troubleshoot.

Hi there and thanks for the reply.

Unfortunately increasing the min AA subdivs didn't help. I'll make sure to send the entire scene for troubleshooting.

Thanks a lot for doing it for me, it's not the first project it has happened so I would surely appreciate some help.

[Joelaff]

If you ever do find the solution please do post here.

[hermit.crab]

Thanks for the provided scene. You have a ton of lights and the Adaptive Lights setting is set to its defaults. You need to either increase the amount or use Full Lights Evaluation (will be slow).

[akis_kyriakopoulos]

Thanks for the provided scene. You have a ton of lights and the Adaptive Lights setting is set to its defaults. You need to either increase the amount or use Full Lights Evaluation (will be slow).

Hi and thanks for such a quick response. I really appreciate it.

The Adaptive Lights option didn't help at all even if I increased the amount a lot.

The Full Lights Evaluation can do the job but the render time is almost infinite. Even with the Chaos render farm is impossible.

I deleted all lights apart from the beam ones and the result in both cases is as per attached.

However, I need all these light instances because I have been asked to provide an aerial render of a hotel during an event at night. Do you think it is possible to achieve that?

Thanks and regards,
Akis

[vladimir_krastev]

Hi, one possibility is render the beams separately and add them in post. Using the VRayLightMix and the other render elements can make this an easy task. You could also try with Volume Light instead of VRayEnvironmentFog and standard lights for the beams. This won't produce as realistic result as the VRayLight though.

[Joelaff]

The adaptive lights thing makes sense. I wonder if increasing the number of Light Cache subdivisions would help, giving it a better chance of finding the correct light. (Like to 10000-20000)??

[hermit.crab]

Increasing LC subdivisions would definitely help (I just noticed you are using the default 1k samples). Also, to speed things up increase the VRayEnvironmentFog's Step parameter - it's far too low. A rule of thumb is Steps = Fog distance divided by 2-3.

[fixeighted]

This is something I was going to suggest (of course you meant 'increase' rather than 'reduce') should help.

I ran a few tests and the randomly tweaked attached image took 9:26 and I'm confident it can be reduced further.
That's using a now pretty old 3950X.

EDIT: I should have said that as a baseline the scene is using 40 lights, adaptive lights set to 40, LC 2000, default AA/everything else.
Env fog as set in the OP's screenshot but with 8000 distance/1000 max steps.

[fixeighted]

So yeah...I can't see any real issue with this, as long as it's tweaked for the scene to get the best times, which for this example I reduced to a few minutes (attached), or seconds depending on some acceptable hacks.

There is one little thing I noticed. As you can see in the attached, where there are odd outlines in some areas and and smudging on the left side and lowering of light value in those few beams.
Maybe that's some bug or is soluble in another way.
This wouldn't be a problem in any final render though, as if I was doing this, I would hide all unnecessary geometry and just render the volumes to comp later.