weird window reflection when changing IOR

[stayinwonderland]

 

so I've rendered a strip in the middle of the window where the issue doesn't seem to be present (IOR un-checked) and it reflects the far scenery (a large plane with an image texture). The rest of the window will abruptly stop reflecting half way down if I have reflection index set to 1.6

 

I feel the overall reflection realism is better at 1.6 though. Taking IOR off makes it look like a mirror.

 

Mainly confused by why it abruptly stops though, tried everything to troubleshoot it.

Edited March 28, 2016 by stayinwonderland

[Corey Beaulieu]

I feel like this problem goes away when you lower the Refraction value to something like 80%. I think the Fresnel value just shuts down the reflections at 90 degrees and this helps it read a little more.

 

You could also try this:

 

Un-tick Fresnel in the reflection and then use a Falloff Map in the reflection slot. After this you can use a grey color instead of black and then whatever white value you would use otherwise. You can set your Fresnel in the Falloff Map. Using the Falloff Map sets the value of reflection at perpendicular angles to a higher value while still following the Fresnel curve at the glancing angles.

 

...and un-ticking Fresnel without the Falloff Map does turn into as mirror as it essentially says that at any angle, the reflection value is nearly perfect.

[stayinwonderland]

oh man, embarrassing. It was the wooden wall at the back that was doing the reflecting! not the glass at the front. I had that with no fresnel at all so it was mirroring the background and the reflection was terminating because the overhanging roof was acting as a block. D'oh.

 

but I still used your tip for the fresnel in order to make the (now working) window reflection look just right. It's a great way to hone how reflective you want a glass pane to be. Thanks