problem with volume light: standard light vs photometric light

[ROSEMEIERMEYER]

Hi everyone!

I want to create a spotlight (!) - based on a photometric light - with an atmospheric volume light effect. So far no problem at all.
BUT: Rendering the scene with vray (2.10.01) lets the fog appear very noise ... not to say brutally ugly.
When I create a spotlight - based on a standard light - with the same atmospheric volume light effect, the rendered scene looks fine.

Can anyone reproduce that phenomenon and - much better - give a solution to me?

Thanks for an answer
Jan

[stevesideas]

Is your noise threshold set low ? Are your global sub d's high enough ?

[vlado]

Is it a VRayIES light or a 3ds Max one?

Best regards,
Vlado

[ROSEMEIERMEYER]

Is your noise threshold set low ? Are your global sub d's high enough ?

Thanks for your answers.
I just tried to increase the noise threshold and the global subdivs - but it did not give a satisfiable solution. The volume-fog of the light is still noisy - not as much as before but the noise is still there and the rendertime grows brutally!
I even tried to change the images sampler type (from adaptive subdivision to adaptive DMC) and played with the settings - but still the same effect.
Finally I had the idea to change the type of the Antialiasing filter - it also did not help.

I definitely do think that the problem is not on the site of the vray-render-settings, because the volume-fog of a standard-light and nearly any other light looks brilliant with my vray-settings!
The photometric light only shows the effect when I switch the "distribution type" to "spotlight"!
If I use it as an "Uniform diffuse", "Uniform spherical" or even as an "photometric web" with an assigned IES-file the volume-fog look fine.

What am I doing wrong?

[ROSEMEIERMEYER]

Also thanks for your answers, Vlado.

IES-light does not show the effect.
Please read my reply to stevesideas.

Thanks
Jan

[vlado]

Well, if you can post your 3ds Max scene, it will be helpful. I could not reproduce the problem here in a simple test.

Best regards,
Vlado

[ROSEMEIERMEYER]

Well, if you can post your 3ds Max scene, it will be helpful. I could not reproduce the problem here in a simple test.

Best regards,
Vlado

Done!
You can find it in the ZIP-file together with a rendered image.
Thanks for your effort.

Jan

[vlado]

Thanks; I think it's a problem with the 3ds Max photometric light - I get the same problem with the scanline renderer too. I'm not sure what can be done about it. You could try using the VRayEnvironmentFog, but it's not quite the same.

Best regards,
Vlado