Any way to use old school volume lighting?

[Seraph135]

I love the look of VrayEnvironmentFog. But its just so slow to get clean results. Is it possible to set up ANY type of light to get volume lighting similar to maya's old school lightfog, but still render in Vray?

Thanks,

Tim J

[aweidenhammer]

It took me a long while to get the hang of getting fast-ish envFog renders, but it is possible. been discussed on a few threads in bits and pieces, but here's the gist that I've found works well:

1. Obviously set up the fog distance to be scene appropriate
2. do not use a pure nederhorst/universal setting for adaptiveAmount. You should use say a .95 for adaptive amount. That way, the samples you plug into the fog will have some effect.
3. up the samples for the fog. This will be dependent on the adaptiveAmount setting, but if that is at .95, then 256 or more fog subdivs is a good start for clean fog renders
4. If you want a stronger effect, without futzing with all the other settings, you can put the color value over 1. I did underwater rays and set the color value to 5.
5. use direct lights. The rectLights will not produce "beams" as clearly as a spot/direct light, since they project rays in 180degrees from the light. This changes in vray2, since you can turn on light directionality.

I'm currently rendering a scene (fairly simple interior with character animation) with full GI, irrad, MB, DOF, many elements, and yes, fog... in about 10-15 min a frame at 720x405 (older xeons too). For the quality, I'd say that is nifty. The biggest change in workflow for me was to not use fully adaptive, and plug in some of my own subdivs on noisy bits. That goes for AO and some of the larger area lights too.

Andrew

[joconnell]

I did a fair bit of this recently and found that in max, adaptive subdivision and an override with everything as a black material was damn quick. There also seemed to be bugs in certain procedural maps so there might be something similar in maya.

[vlado]

...There also seemed to be bugs in certain procedural maps so there might be something similar in maya.

Nope, there isn't

Best regards,
Vlado

[Seraph135]

Hey thanks for the input guys!

Andrew....I've already tried all of those things you mentioned, unfortunately. I have about 12 vray sphere lights in my scene. Just to help out with any other issues that may come up later I've decided to put a matte override on the whole scene and render the fog in a separate pass and composite it back in later. Its not ideal because I'm not getting the reflections of the fog on the environment...but it renders a lot faster (about 1 hour). I didn't have any luck with jconnell's recommendation either. Render times were actually considerably longer...but I wasn't using a black material. I was putting a matte override on everything so I could get an alpha for compositing.

I'd love to hear any other suggestions you guys might have.

Thanks,

Tim J

[joconnell]

Nope, there isn't

god damn shitty 3dsmax

[vlado]

I'd love to hear any other suggestions you guys might have.

Do you use any textures for the fog? In any case, without a scene for testing, it's hard to figure out how to optimize it.

Best regards,
Vlado

[bazuka]

.............

[aweidenhammer]

Wellp. As Vlado mentions, I'd have to roll up my sleeves and dive into the scene... but that's not gonna happen But here are some additional thoughts:

1. Are the sphere lights visible to camera? If so, the slowness might be in part, the sampling of an overbright source. Use subpixelMapping and clamp values at 2 or so to prevent slowing down too much there.
2. Using a matte property is certainly an intelligent way to attempt to comp the atmos... but I have found it (matte) can be significantly slower than using a black, or white material (as jconnell mentions). We had very fast fog passes; a few minutes in HD by using a separate pass with basic vray mats on all objects. Comping was not ideal, but it worked fine with some fiddles.

To answer your original question more directly, no, I haven't found any way to use Maya fake foglights in vray... though we have rendered some as maya passes to be comped later. Good luck.

The sphere lights issue does seem a bit slow. A quick test shows that it is a lot slower than my scenes, where my lights are not directly visible to camera. You might try making the lights themselves invisible... not sure that would help though.

Andrew

[Seraph135]

Do you use any textures for the fog? In any case, without a scene for testing, it's hard to figure out how to optimize it.

So far not using any textures in the fog. At the moment not planning to, but it might be necessary at some point.

1. Are the sphere lights visible to camera? If so, the slowness might be in part, the sampling of an overbright source. Use subpixelMapping and clamp values at 2 or so to prevent slowing down too much there.
2. Using a matte property is certainly an intelligent way to attempt to comp the atmos... but I have found it (matte) can be significantly slower than using a black, or white material (as jconnell mentions). We had very fast fog passes; a few minutes in HD by using a separate pass with basic vray mats on all objects. Comping was not ideal, but it worked fine with some fiddles.

The lights are invisible to camera, but they are within the camera's fov in many shots. So even though I'm not directly seeing them, I am seeing the bright halo's around them in the fog. I'm also clamping at 3 and have sub-pixel mapping on.

Maya's render layers tend to corrupt very easily in my experience so I'm trying hard not to set up material overrides unless I can't help it. I will try setting up a separate scene just for a black material on everything and see how that goes. Without having a proper alpha for the fog though its not going to look like the beauty pass. But with some compositing love it might be ok.

Unfortunately, rendering a maya software pass of volume light won't work because my scene has displacement.

I appreciate the help guys. Thanks for your ideas. I'm going to see if changing the amount of segments on the sphere lights has any noticeable affect as well.

Tim J

[vlado]

Not sure if you have GI on, but enabling it may also help to clean up areas close to the lights.

Best regards,
Vlado