volume fog lights (God rays)

[tinuz]

looks great! now you made us all curious!

[bernhard]

yep, looks nice... did you put an alpha map into the light source in order to get the nice light-streaks ?
By streaks I actually mean the god-rays, not the caustics on the ground.

[gardeler]

I noticed in some tests I did that it was very hard to achieve fast/good rendering with dmc AA. Using adaptive made the renders both quicker and and a lot better.

[bazuka]

i have a caustic seq map attached on the (spot) light color and thats it, thats the light/rays streaks that u see and the caustic on the ground (everything is the same)

setup is really simple, i dont have anything in the scene, 1 light, objects and the vray envfog , maybe ill will share scene, im not sure yet coz its a part of commercial i did.

im still waiting for client approval for uploading the video on my vimeo

[bernhard]

makes sense with the map... about the objects... for the water you used a plane and positioned the cam below ?
Or did you use for the "water-object" itself something additional ?


I made a quick test with real caustics. Low render quality, just a quick check how it works straight with all vray options.



Vlado and you mentioned earlier, that you create a box and limit the vray_env_fog to calculate inside this bounding box only.

I couldn't follow you - how you do that ?

[vlado]

The environment fog is a Set object in Maya as well, so you can use the Relationship editor to attach fog gizmos to it.

Best regards,
Vlado

[bernhard]

ok, got you... thx a lot.... I was really curios and made this quick test:

No Bounding Box used:


With Bounding Box:



Surprisingly, the scene with the bounding box takes longer to render !?
Because of the opacity ?

Wouldn't have expected that result.

Do you know examples where you have really significant differences in render time ?
What means... EnvFog Bounded vs. EnvFog ?

Thx a lot

[vlado]

Do you have the gizmo fadeout option enabled (doesn't look like it, but I thought I'd ask just in case)?

Best regards,
Vlado

[bernhard]

If you are referring to the Fadeout options inside the VrayEnvFog Node: Yes, I changed the radius of the fadeout as well, made some tests as shown below.
Or did you mean something else ?

radius: 0, what means no fadeout



radius: 0.001



radius: 1


radius: 10


radius: 100



As bigger the fadeout radius value, as higher the render-time: what makes sense.
Overall additional a good option ... and it looks like it makes sense to keep the radius on a really low value to decrease render-time.

I think it's good to check that option and test it, as you can increase or decrease your render-time.

[aweidenhammer]

The one trick I've found to enhancing the "shafts of light" in envFog, is to crank up the fog's color value. In one scene similar to Bazuka's I used a caustic map on a spotlight. I couldn't get the contrast to the shafts of light, until I raised the fog color value to like, 10.

Andrew

[aweidenhammer]

... and yeah, using this method has pretty fast rendertimes. My HD frames are like 5min... but the scene is much more complex than the examples here. lots of particles and motion blur.

[bazuka]

ok here r the settings, hope it will help u

[pg1]

hey bazuka,
I am trying something similar in max at the moment. Because you used an animated caustic map on the light did you render it brute force light cache or was it done with an nth frame irmap?

[bernhard]

@Andrew:
Hmm, this is really interesting... hmm.. now I am more curios.. I tried to speed up things and set the fog color value to 10 and higher... but I can't see, that it renders faster ?
Did I misunderstand or do you setup your scene in a completely different way ?

Or did you mean the emission value ?
Cause if you set the fog color to black, and you use just the emission color only, things will speed up !

[bazuka]

@pg1

i used the IR/BF and i didnt use the irr map, i used the single frame method , let me fire up the max and ill try to make the same thing there i hope