No reflection when refraction is on?

[MANUEL_MOUSIOL]

I have no reflections whatsoever on my windows.
Why is that?
Reflection is on 100% (fully white) with an IOR of 1.6
Refraction is also 100% with an IOR of 1.33
Windows look like there not even there...
I dont even know how to fake this to go around this problem...

[glorybound]

I have to use the RAW reflection in post-production. I have mentioned this way back when NEXT came out. It seems to not be a bug, but just a different way VRay is working.

https://forums.chaosgroup.com/forum/...update-1-glass

[MANUEL_MOUSIOL]

It doesn't sound right .... Shouldn't be that way

[glorybound]

It was probably a fix for something else. The post says that if you combine the reflection and specular, in post, you'll get the reflection you expect. I guess they expect all images to get some post-production and people render out those two passes. I do, but some just want to save from the VFB.

[MANUEL_MOUSIOL]

I have to check .last time i rendered out specular pass my windows were black. And it's an interior .so something has to reflect in there,right?
I'll do another test ...
Anyway, I am discovering doing all my post work in the VfB and like that workflow for interiors .so I'd had to go into Photoshop just to get proper reflections in my windows .

Thinking of it .It's strange that for example my glass table has proper reflections and refraction but the windows don't...I'm getting confused...

[glorybound]

I don't get it either. My feeling is, they have a cheat to speed things up.

[MANUEL_MOUSIOL]

But why would vray know it's a window? Because it's 90 degree? I really have to test this...

[MANUEL_MOUSIOL]

ok, here are some test results.
I think maybe we stumbled into the difference between our anticipation of reality and the real calculation of it:
My production interior scene is strange. I tested it with lights in the room. No refraction on the window material gave proper reflections of the sphere light. Turning refraction on seemed to make them disappear. But, turning the dome light way down made the bulb visible again. So against the bright backrgound it is just not visible to our eyes, but it is indeed there.

I had one time where reflections didnt work at all, even on a simple mirror like material. I had to restart IPR to get it working - that is a little scary, especially since I cant reproduce it; but it happened to me several times already. see the pictures with the plane in the room attached.
I dont understand why that plane wouldnt reflect. appr. same position as the sphere light.
I did another test with a plane afterwards. gave it a color instead of pure black, and it reflected fine..

I also noticed that turning reflect on backside option helps to make the reflection a little stronger. rendering times will be slower though..

[MANUEL_MOUSIOL]

look at the other sphere test with simple geometry. reflection is very thin when refrcaction is on, turning reflection IOR up is of course giving stronger reflection, but by doing so you will get less light coming through as the material turns more and more into a mirror.

[MANUEL_MOUSIOL]

I also had what I think was a converted glass material from corona. It didnt reflect at all, even when turning refraction off and turning the material like a mirror. I had to recreate the material and reflections worked properly. so...dont know why this would happen as all the options where the same.. but one point more to be careful.
also, what I didnt know until making these tests: a simple plane wouldnt give me proper diffuse reflections until I made proper geometry out of it with the shell modifier. it was just pure black on one side...