sampling behind glass problem

[rivoli]

I have a scene which shows some drastic changes in sampling if objects are rendered behind more than one glass layer. I've attached a couple of images to explain what I mean. in scene there's a glass wall, on which can be seen the environment reflection, and other glass in the windows frames. the first image looks fine, as I removed the glass at the window so the railing and pillar are sampled correctly. the second one shows the problem, as those same objects, once the glass at the window is unhidden, are heavily undersampled. sampler is fixed, but the same thing happens with progressive and adaptive as well.

edit: I forgot, vray 3.10.03

[tashko.zashev]

Hi,

Would it be possible to send us the scene file or post it here ?
Thank you.

[rivoli]

yes of course, I'll strip down the scene and upload it here later. thanks.

[rivoli]

sorry for the delay, had a busy day yesterday. here's part of the scene I'm working on. admittedly I didn't have time to check other scenes to see whether the problem is consistent or not, it may just be this one scene or something dumb from my part (quite likely). anyway, thanks for taking the time and look into it.

[tashko.zashev]

Thank you for posting the file.

In order to get better/clean render result for this scene setup you can rise up the Dome light and GI brute force subdivisions. In my tests values around 24 should work fine, but this will force the engine to spend more time for sampling that area.
Furthermore I see that "Min Shading rate" parameter is set to 128, which may lead to similar render results. More samples are used for shading and less for AA.

[rivoli]

thank you for looking into it. more subdivisions will certainly fix this, but what seemed odd to me was the sudden change once adding more than one glass layer.