Interior Glass

[MegaPixel]

Do you use Multisubobject Materials by chance? If I recall, Glass materials that were nested within MultiSub materials didn't react with the GI properly (This may have been fixed - I don't know). As suggested above, Detaching my Glass ID's seemed to make a difference.

-Pixel

[MoonDoggie]

hmmm.. the inverse and the alpha settings just become available when i have an image plugged in any shading slot, which I don't need for glass. so where can I set that values else?

I'm not sure what Cubiclegangster means by "inverse", but what I think he means is

create a fully reflective material (white 255 in the reflection slot)

then in the VRayProperties for the object (select object, right-click in viewport, "V-Ray Properties") then set the "Alpha Contribution" to -1.0. Is that right Gangster? I'm curious what you mean too.

[Sacha]

hey colin,

that sounds better to me =) I'll give it a try.. thanks for the hint!

[MoonDoggie]

Sacha,
Yeah no worries, I'm curious too, because I've always rendered it in render because you can't get reflections on matte objects so I've never tried with a separate pass. I hope Cubicle shares his secrets

[Neilg]

Whoops... didnt mean to overcomplicate it. i meant ctrl + I - select inverse of the objects. you dont want them to render, you only want the glass object to render.

So yeah:
you select the glass object
apply a fully reflective material
select every other object in the scene
change vray properties to alpha -1 and check on matte object (forgot to mention that)

[MoonDoggie]

I didn't think you could get the reflection on the glass off of matte objects. I'll try this, thanks for the tip CubicleGangster.

[Sacha]

ah ok... thanks guys!! helped me a lot!

[pailhead]

is this still rendering the entire image? How long does it take to render?

[Sacha]

hey dusan,

yes shure it renders the entire image, since it needs all the information for the reflections. Takes unfortunately the same time like the main render.

[pailhead]

thats where i was going lol,

cant this be done with simply masking the glass, using the reflection layer etc?

[Sacha]

I did it that way and it worked fine.but I had some problems with the background in conjunction with a reflective and refractive material outside (behind the glass) the room, so I was looking for a better solution. you have to play a bit more with the alpha by taking the first solution. with the one suggested by cubic and colin, you have the reflection pass right by your hand. But the extra time it takes to render is even more than that for playing with the alpa.
But since I'm very new to the whole vray stuff maybe I'm wrong...
So now I have two ways to choose from, depending on my environment perfect!

[Neilg]

It doesnt take anywhere near as long as the original - they're incredibly fast for me. on a 4/5 hour render the glass is usually a 30 minute local render on lunch.
It shouldnt be rendering the whole image either - are you sure you did it right? It only renders the glass object.

Being that your original render had no glass, and this ones only rendering the reflected parts, i doubt the overall time is all that much longer than doing it all together. simplifies the lighting too.

[Sacha]

I have three sss lamps wih very high material subdivs reflected in the glass.. maybe that´s the one, pushing the time up. for the rest i also thought it goes faster. but I guess you're right. just for the some buckets where the lamps are it takes up to an hour with scatter gi turned on..