Vrayenvironmentfog issue

[eric_barbaron]

Hello, I need to simulate a light show with volumetric lights, as in a concert.
I tried the vrayenvironmentfog effect but it's extremely slow to render...Too slow in any case with the default settings.

Moreover, I need to simulate very tight lights that are close to 1, a bit like lasers (sharpy lights) and in this case, the particles take even longer to render and the beam of light is cutted in some places if i set the directional of the disc light to 1 ???!

Is there a setting that decreases the rendering time, even if the quality is a little less, and fixes the cutted beams ?


Here is some pics to explain

Thank you a thousand times for your answers and/or your solutions

[hermit.crab]

Odd. Doesn't seem to happen in a simple scene. Could you strip your scene and send it via the contact form (or attach it here) so we can take a look? Address it to me in the subject and include a link to this thread in the message.

[Joelaff]

Try old school Max volumetric lights. Or try transparent luminous cylinders.

[eric_barbaron]

Hi Aleksandar ,
thx for your reply.
I uploaded the file.
Hope that it will help

[eric_barbaron]

hi Joelaff
i know i can use old school volumetric lights, but its doesnt work as well as Vrayenvironmentfog

.

[hermit.crab]

eric_barbaron Thanks for the provided scene. It seems the issue is present due to the AA samples missing the light itself. To resolve this, try increasing the min. subdivs in the Image sampler (Render Setup>V-Ray>Image Sampler>Min subdivs) to i.e. 3-4.

[eric_barbaron]

Same issue
even if I increase to 10… and its very very very slow to render

[Joelaff]

hi Joelaff
i know i can use old school volumetric lights, but its doesnt work as well as Vrayenvironmentfog

.

You said you wanted fast

[Joelaff]

Also. try a blank VRayVolmeGrid that you give some opacity too. This usually renders faster than VRayEnvironmentFog (make sure probabilistic shading is enabled, which I think defaults to on now).

[squintnic]

I end up doing these with old school volumetrics, geometry with opacity and light materials or vray enc fog and rendering seperately on black on lower settigns and then mashing everything together in post (fusion in my case)

Vray GPU is much faster at volumetrics but having to up the AA to 3-4 min to get no artifacts makes it really slow.

I wish there was a quck and dumb way to do these cos I use volumetrics in every single job which led me to Vray GPU but its still very slow and gets worse on complex scenes where you need to exclude from lots of stuff.

Basically its the same as 2007 where we rendered it all seperately as a matter our course!

[hermit.crab]

Lowering the bucket size might help in some cases, however, this kind of brute approach is surely not optimal (very slow). We are aware of the phenomenon happening with direct lights, however, there isn't much we can do at this point. For now, either stick to using values lower than 1 or use the 3ds max natives ones in order to avoid extreme render times.

[^Lele^]

A direct light, with V-Ray shadows, and with Max's own "Volume Light" effect works best in these scenarios.
It's quick, it's very directable, and no one is going to notice it's not a 100 bounces GI solution inside a volume.

EDIT: *Some* of your cutoffs are because of odd volume setup: increase your volume fog "emission" and you'll notice the beams cut right below the fog height.
You should consider using a box Gizmo around the building,instead, to enclose your volume.

Notice that what Alex mentioned above is correct: values too close to 1.0 (0.998, f.e.) will still result in poor sampling, and you should really move to max direct lights (or tight spots, as you need.) as explained above, with or without the max "Volume Lights" effect (while slower, the global volume works just fine with max lights.).

Attached: from left to right, original tight disc, direct light, and tight spotlight.
The volume's enclosed in a box gizmo, "Scatter GI" is off for speed.
Rendered with 4-24 @ 0.01 noise threshold, quite quickly (for three beams only, ofc.).

[flat]

Limited to Max 2017-2020, ScatterVL Pro is free.
http://www.afterworks.com/Freeware.asp

The physical base is good, but I also want V-Ray to have this kind of artist-oriented fake function.

[eric_barbaron]

Hi,
and thx a lot for your replies.
I finally decided to spend more time to render and keep Vrayenvironmentfog for the others lights except for sharpy lights
Thx to LELE to spend time for me.
Hope to see new features in next vray's