Glass refraction

[pietervanstee]

Hi,

I'm rendering an interior scene, looking out through the window.
This causes a problem in the refraction (I guess, unless this is physically correct).
The windows are generated with Railclone, and the glass consist of a double panel glass (4 planes/ 2 boxes)

Is there a way to fix this?
Thanks

[cheerioboy]

Isn't that a reflection? Not sure I see the problem. It's probably hard to isolate with channels since there are so many pieces of glass there.

[pietervanstee]

Yes I think you're right.
Looks more like the reflection in the first glas panel.
I was asking about this issue because in my testrenders I had the following problem (see attachment).
Some kind of weird refraction... but then the glass was still triple layered so 6 planes or 3 blades of glass.
That issue is gone now it seems.

Any chance someone knows what the issue here could have been?
Thanks

[Macker]

What is the index of refraction? The higher it is, the larger the deviation will be when it enters the glass, which will of course will be corrected upon exit, but if the glass is really thick it'll have deviated enough to create a noticeable difference; an issue that can be compounded over several sheets of glass. Glass panes in real life are usually ~6mm thick, and unless they have a solar control coating, have an index of refraction of around 1.5.

[pietervanstee]

Hi Macker,

The thickness was about 6/7/6mm (three planes of glass)
With a refraction of 1,6 which is quite realistic I guess.
Removing the middle plane of glass fixed the refraction problem.

The issue I posted first will be accurate as it's the reflection on the first and closest plane of glass.
Thanks for the response

[Codi]

Might be due max depth setting of the glass material? Try to change it from 5 to 7 or so.

[pietervanstee]

Hi, codi, that must be it.
Havent tried this camera again, but indeed the max depth was 5.
I've changed it to 7, but is that enough to get through 8 planes of glass (2 windows), or even 12 (when looking through the 3 windows)?

Thanks

[m_hinks]

I believe you count based on 1 entry and 1 exit, so 2 per sheet/object of glass - I would think for 12 sheets of glass you'd need 24, plus a couple in case anything is visible through all that glass that is also reflective. But I might be wrong!

[Codi]

7 should be enough for the rays to cross three glass planes as you said you had, add 2 ray depth for each glass you expect it to cross, or raise it to ... 100 (1000?) to not worry about it. I doubt it will make increase your render times a lot in you case, should test it to be sure tough.

[pietervanstee]

Hi both, thanks for the help, I'll try with 24+ depth for this case.