Tricky glass problem

[artykris]

Hi there,

I wonder if you guys can help me to get a desired effect in this render.

It`s the glass I`m working on, problem is that the glossy steel structure elements behind the glass loose their glossy reflection (please see the att. image).

I think the issue here is that glossy reflection dissapears behind glass?
How can I tweak Vray settings to get it sorted? Maybe I missed a check here and there...

[img=http://img394.imageshack.us/img394/8627/glasstweakrenderjb4.th.jpg]
http://img394.imageshack.us/img394/8...krenderjb4.jpg

I`m using VrayCam, VraySun & VraySky for environment GI only.
The environment background and refraction override is set to black.
The reflection override is set to light greenish colour.
The glass elements are shelled polygons 1cm thick and they have cast/receive shadows unchecked.

I`m on Vray 1.5RC5, max9.

Thanks for your help!

[instinct]

Well you have a black refraction override. That means that through refractive objects (=the glass) the environment is not seen. To the inside materials that means they cant see the environments as there's always glass in front and hence it is overriden to black. untick the refractive override and it'll be fine.

Regards,
Thorsten

[instinct]

Oh and in addition your glass is creating an opaque shadow. You should also tick "Affect shadow" and "Affect Alpha" in the material settings. (That alone will bring back light, but no reflections)

Regards,
Thorsten

[artykris]

Thanks, changing the refr. override solves the problem.

But now don`t have a black background through the glass.

Any ideas how I can accomplish that?

Thanks instinct!

[Pixelab]

Your refraction IOR is 1.0, that's strange for glass. Try 1.5 but that's won't solve your problem. Also try to raise the max depth for reflection in the steel material.

For this kind of issue, I usually don't make the glass visible to GI. That leads to a slight "physically incorrect" rendering but it speeds up the render and solve the glass and GI issue.

[artykris]

Pixelab->
Yes, I tried using override material on Glass mat. and turning GI off.
But this blocked GI from entering the interior.

As for my question about black background through the windows, I only have one idea currently - postprocess it basing on alpha channel. This is going to be an animation.
Any other in-max solutions?

Thanks all for immediate response, you`re great!

[artykris]

OK, I`m answering my own question here, but maybe someone finds it useful:
I managed to overcome last problem - I have used a huge black sphere, with visibility to camera off, visibility to GI off, visibility to reflection off.
This way I have a black refraction in windows (against background), while preserving all the glossies and reflections.
Works great.