Trouble with volume light

[markf]

I have read a number of threads here about using volume light with Vray. I am having trouble with it.

 

I have a target direct light shining through some windows. I have Vray shadows enabled. If I change to shadow map and assign the volume effect, the shadows get very washed out.

 

I tried making a clone of that light and using it as the volume light. I read in the other posts that the volume light could be "tuned off" and still show the volume effect without adding extra illumination to the scene.

 

Unfortunately, when I turn off the volume light the volume light effect goes away. If I reduce the multiplier to 0, the effect goes away. If I exclude all of the geometry from the lights illumination, the effect floods the entire scene in an overwhelming and intense way.

 

Is it possible to have the volume light turned off and still get the volume effect?

 

Thansk in advance for any help.

[WAcky]

Are you using vrayenvironment fog?

 

If not you should give that a go instead of using the standard max effects.

[markf]

thanks for you reply James. I am not using Vray environment fog. I'm using the Max volume light effect, assigned to a standard target direct light.

 

Is Vray Environment Fog able to be assigned to a light , so as to simulate a "volume light" effect? I'm trying to achieve the "visible sunlight illuminating some subtle atmosphere/dust as it shines into the room through the windows" look.

 

Thanks Again!

[WAcky]

Yes it works with both gizmo's (including meshes) and lights.

[markf]

James,

 

I looked at trying the vray environment fog. I couldn't seem to assign the effect to a light. I could create an atmospheric gizmo and assign the effect to that but that didn't give me the results I needed. There is a section in the Vray environment fog dialog to include lights, but if I understand correctly, that is just to tell vray which lights will illuminate the fog.

 

Below is a link to my rendering showing the max volume light.

 

http://www.openrangeimaging.com/test-posts/707_Living01.jpg

 

Thanks for your help!

[Tommy L]

Mark,

Simple answer would be...dont use volumetric light effects. You shouldnt use it in 99.9% of arch rendering, especially a scene like yours. It just makes it look like there is dust in the room.

[markf]

Tom,

 

Thanks for your reply. I wasn't aware it was such a "not to be used effect" for architectural rendering. You are the second person who has suggested that I not use it so I'll probably get rid of it.

 

Thanks again.

[Tommy L]

MArk,

Youve actually been quite subtle with the use here. I find that its only really successful in arch-vis when its subtle and used in very large bright spaces such as glass atriums in shopping malls. I used it a couple of times and the client requested it removed on both occasions (both said it looked dusty)

Its main boon is in non-arch-vis work, such as castles, caves and jungles. Its an atmospheric effect which is the only tool of its kind to convey 'airborne light'. I liken it to DOF. Right place, right time, its awesome.

[Stephen Thomas]

I think you could actually afford to go a little denser with the effect but the key, in my opinion, is to limit it to the area immediately next to the window. I normally do this by snapping an inactive target direct light (set to shadow map) to my vray sun and linking this to the volume light effect. This means that my vray sun controls the illumination and I can use the far attenuation values on the direct light to control the limits of the volume light effect. Set the start distance to just outside the window and the end distance somewhere between the window and the floor so you get some falloff.

[WAcky]

In sp3 you could only assign the effect to a gizmo. Update your Vray to sp4 and you will be able to assign the effect to a light.

[markf]

James,

 

I'll get sp4 going soon.

 

Stef,

 

I am using a Max standard direct spot for the sun. Not using Vray sun. I cloned the light and set it to use shadow map. If I turn it off the fog effect dissapears. It is contributing to the illumination and I excluded the floor.

 

I don't seem to be able to get the effect to work if the light it is assigned to is off.

 

This is probably all moot now that sp4 apparently allows a better solution.

 

 

Thanks!

Edited November 4, 2009 by markf