Render artifacts

[JeffG777]

I'm having trouble rendering this scene. I'm in 3ds max 2018 and the latest version of Vray. The smoke sim is from the beta of Phoenix.

My hazard/siren lights are not casting correctly. In the still picture, you can see where part of the light is missing almost like something was blocking the light. Yet, there is nothing there that should be blocking the light. The artifacts are not consistent... I go and make some changes hoping to fix the issue then render again. When I render again the artifacts aren't in the same place. I've spent a couple of days trying different ways of getting rid of the issue but it persists. I would appreciate any insights.

This video shows the issue. Watch the hazard lights as they spin. You will see spots that look like shadows... yet there is nothing blocking the light.
https://vimeo.com/377465275

Early on the problem was worse. You could see it in the sim as well. As seen in this video.
https://vimeo.com/377467805

Any help getting rid of these artifacts would be awesome!

Jeff

[vlado]

Try setting the shadow bias to 0.0, also maybe try disabling the shadows altogether to see if the issue is still there? Also what type of lights are these? (Seems like directional disc lights, but not sure). If you hide the smoke are they still there? I’m not sure if you sent the scene before, but it would be useful to take a look,

Best regards,
Vlado

[JeffG777]

The issue is still there when the sim is disabled. I'll try the shadow bias.

How/where do I send the scene?

[JeffG777]

The siren/hazard lights have 3 lights altogether. In the center is a vray sphere light, then an invisible vray disc light inside the glass housing pointing at the reflector and a VRay IES light on the outside of the glass housing casting the light.

I'm open to suggestions on how to construct the light better as far as the lights go!

[vlado]

I think the construction of the light is fine; if you can send the scene to vlado@chaosgroup.com I will be able to take a look.

Best regards,
Vlado

[JeffG777]

I sent the file. Thanks for taking the time to take a look!

[JeffG777]

I was wondering if there was any news on this issue?

[vlado]

Yes, the problem is that you have the light cache mode set to "fly through"; this mode is useful if the camera is the only thing that is animated, but in your case there are moving lights and moving objects. Setting the light cache mode to "single frame" solves the issue.

Best regards,
Vlado

[fixeighted]

Now this is why every seat of Vray should come with a free intern who sits by our side and softly says.... "now, did you check that you've done...."

[^Lele^]

We (meaning I.) really need to write proper comparison guides and show people why it is we suggest certain workflows.
Having those old options in the UI surely is no help, however now we have the Defaults set up right, and tooltips all over the UI.
Maybe we should go radical on the UI for 5, and good riddance to the old stuff? What say you?

[kosso_olli]

Maybe we should go radical on the UI for 5, and good riddance to the old stuff? What say you?

Yes, completely radical! There is so much unneeded stuff in there, seriously. If you need any suggestions, tell us.