Spots and Blackout Irradience Map Calc

[julie]

Vray Masters:

I've been told that using raytrace maps causes render errors with V-ray, but has anyone ever encountered problems using falloff maps in the reflection channel? For this particular interior scene there is a glass v-ray material with a falloff map in the reflection channel that seems to be causing blackout during the irradience calc phase when using Irradience as 1st GI bounces and LightCache as 2nd bounces. Changing it to QMC for the 2nd solves this problem but random spots appears in the final rendering phase.

Testing the same without falloff maps in the reflection channel of the glass material seems to make the problems go away in both render settings. Though this maybe a combination of other factors at play? Attached are jpgs illustrating the outcomes with screenshots of the scene/render setup.

Perhaps someone might know what might the real cause? It is traumatizing me not figuring out.

www.designstor.com/files/LightCache.jpg
http://www.designstor.com/files/Ligh...loff_Glass.jpg
http://www.designstor.com/files/Ligh...screenshot.jpg

www.designstor.com/files/QMC.jpg
www.designstor.com/files/QMC_Falloff_Glass.jpg
www.designstor.com/files/QMC_screenshot.jpg

[jacksc02]

do you have any architectural materials in your scene?

[natty]

Hi

what shadow type are you using for those omnis?
i would change those for vray lights and let the Gi illuminate the scene ..

[Candelero]

1/
In the Folloff option rollout in your Glass material,
CHECK ON the Override check-box, as I suppose you are using the < Fresnel > option. That should fix your < darkness > problem.

2/
Also I suppose you if are having a Camera Correction mod, so if < yes >
CHECK OFF - the < Max-Compatible ShadeContext > check-box.

That both should fix your scene !


Best regards,
nikki Candelero

[julie]

do you have any architectural materials in your scene?

no, only v-ray materials.

what shadow type are you using for those omnis?
i would change those for vray lights and let the Gi illuminate the scene ..

all the lights have Vray Shadows selected.

1/
In the Folloff option rollout in your Glass material,
CHECK ON the Override check-box, as I suppose you are using the < Fresnel > option. That should fix your < darkness > problem.

I will give that a try and let you know the result. Can you explain what it is overiding though? As the Fresnel reflections option has not been checked in the VRayMtl parameters.

2/
Also I suppose you if are having a Camera Correction mod, so if < yes >
CHECK OFF - the < Max-Compatible ShadeContext > check-box.

I thought this was the problem so I' had already deleted all the camera correction mod and I also always have the MAX-compatible Shade Context checked off.

Thanks for everyone's feedback, I will check back with you shortly hopefully the overide comes through!

[julie]

1/
In the Folloff option rollout in your Glass material,
CHECK ON the Override check-box, as I suppose you are using the < Fresnel > option. That should fix your < darkness > problem.

http://www.designstor.com/files/Ligh...ideFresnel.jpg
http://www.designstor.com/files/QMC_...ideFresnel.jpg

...and yes, that did fix it. Thank you. I can go to sleep soundly now. Though I'm curious as to why this fixed the problem, is it basically an issue of conflict between the Fresnel of the Vray shader parameter and of the falloff map? Even if the Vray Fresnel option isn't checked?

[olitech]

just a question....why do you have a falloff map in the reflection channel...can't u just tick 'fresnel' ?

i know in older versions we used to add the falloff channel, but that was before reflect and refract had their own IOR

[ene.xis]

yeah...i still wonder why everyone uses those for reflect/fraction purposes....
but again...i might be wrong!

[julie]

I had the same question and the reasons I got from those who prefer using falloff maps are and I interprete as:

1.better control of the amount of reflection in the fresnel, not in terms of its overall intensity but in the contrast ratio.

2. using the same falloff map across multiple materials (ie. different glass) that need to have the same reflection quality gives it global control, so that changing the falloff once is instanced in such case.

[ene.xis]

humm...i see