3dsmax / VrayEnviromentalFog / Beam Lights issues

[Joelaff]

Obviously a larger step size is faster, but what effect, if any, does the step size have on the dropout issue? fixeighted were you saying it actually works better with the higher step size as well?

If you are setting the Adaptive Lights to the number of lights in the scene I wonder if LightTree would be slightly faster?

Perhaps I will give it a little play. Just got my 7995WX system. Eager to play (once I get through all the setup hell).

[fixeighted]

What I've noticed is that the step size has no effect on the dropout, at extremes of high/low, and there's no apparent massive speed increase actually.
Maybe that's due to the setup of the lights; i.e. it's not a solid volume using a texture that needs sampling through, or lots of crossing beams at variable distance.

The single impactful factor is the adaptive setting, with the exact number and light tree giving comparable results I think, though maybe I'd opt for picking an amount equal to scene lights, to avoid any surprises, especially
as I imagine this is an animated scenario.
In any case, if it was my project then I'd split it into bits and comp later for ease/speed, and to get around those awful outline glitches that occur with geometry.

Thanks for mentioning your really really really fast new kit while I suffer with antiquated old crap

[vladimir_krastev]

Just got my 7995WX system

Congrats and many trouble-free hours of using it.

akis_kyriakopoulos if you can't manage to fix your scene on your own, please send it to support. We might be able to help you.

[Joelaff]

fixeighted I did finally get Max running on the system (2023 at least). I was able to play a little bit with a similar setup of lights. With 101 lights I was sometimes getting dropouts even with adaptive set to 800. I may not have ever tried the exact number.

Like your results, light tree seemed to make no difference in speed or dropouts. Full evaluation was definitely slower, even in this new beast.

The post comp approach seems to be the only real production friendly (er) solution. Or using Max lights, which of course don’t do all the scattering. I’d like to try an empty VrayVolumeGrid as well. In the past that has been my go to solution for volumetric in VRay, at least for subtle scattering (possibly not light beams).

Sorry to brag about the new system. I had literally just turned it on yesterday and was very excited! After some preliminary testing I am even more excited, as the performance is everything I had hoped.

[fixeighted]

Hehe...only kidding about new gear...if you have the cash then spend it I reckon ...bigger/better ftw!

I don't have a need for this type of volume situation right now, so I won't spend more time on it (well, maybe a look at that empty grid thing you suggested) but I'll keep
an eye on the post for any cool technical epiphanies/updates

[Joelaff]

Yeah, I don't have use for it immediately either, but it is interesting.

The VolumeGrid trick works (leave Volume Light Cache ON and set it to like 0.1 and try RayTraced with a 0.5 phase function. Render with bucket renderer (because of the Volume Light Cache)). You need a fairly dense grid to avoid aliasing if your light beams are narrow or closely spaced. It works really well for overall light glow/scattering-- not as well for defined light beams without a lot of cells.

The VolumeLightCache does seem to cause some aliasing with multiple lights. Aliasing in terms of the light scattering, not jaggies. So perhaps it is actually better with it off and with Progressive. Better, but oh so much slower.

Play with the minimum visible opacity. You want this as high as possible for speed, but it makes your fine fog disappear.

[Joelaff]

Here is a scene. I actually had better luck with an empty Phoenix Smoke simulator, though in theory it should be about the same with the VRayVolumeGrid (if you don't have Phoenix) It was probably just that starting fresh let me get it looking better.

Play with the Voxel size and the light cache speedup for a speed/quality balance. Note that the Volume Light Cache will be very slow with Progressive or with IPR. Render with bucket or disable it (which is slower).


LightTester.zip