caustics through architectural glass

[vlado]

Yes, I got it. It's strange that the glass comes out dark when caustics are turned on... looking into it now.

Best regards,
Vlado

[Mokiki]

Phew slightly relieved to hear that you also find it strange. Everytime I send you guys a scene I expect the response "Of course it does that because you have the "produce odd result"-button turned on" :P

[Raven]

Created a similar scene and it seams fine here, no darkening. Oliver, you must have the "produce odd result"-button turned on. ha ha

[Mokiki]

Created a similar scene and it seams fine here, no darkening. Oliver, you must have the "produce odd result"-button turned on. ha ha

Ha! :P Quick question though are you rendering with IR/LC or BF/LC? My scene is rendered with BF/LC.

*edit* ignore this post. I seemed to remember some older project where I had some caustics differences between IR and BF. But I just managed to make a quick test myself and both result in identical renders.

[Raven]

Rendered with both, as my first thought was it might be that.
Here is the BF\LC render and the file. Give it a test on your side

[Mokiki]

Hmmm, now I tested a different lightsource. I usually use the max standard light "trick" to produce my caustics and thought maybe that is screwing a bit with the scene. But I just disabled my caustic spotlight and added a vray sun to generate the caustics but while different lighting I get the same darkening of the glass.

*edit* checking out your scene now

[Mokiki]

Checked out your scene and we practically have the same setup. But different results.

*edit*

I had the chance to rebuild the scene from the ground up on another workstation and this time I made sure I had the same setup you had from the start. But the darkening of the glass is still present and I really have no idea what could be the cause of this. Than I started swapping models from your scene into mine starting with the glass than water etc. which resulted in the dark glass. When I saved your render settings as a preset and used them on my scene the darkening is still present. When I open a completely new scene and render with your models, the glass renders fine. When I save that scene and restart max it sill renders fine.

The only conclusion I can draw is that Vlado managed to program a real A.I and integrated it into vray and because I was using weird rendersettings all the time when I started with vray it started hating me. That is the only thing that would made sense at this point. :P

[peterguthrie]

Vlado, didn't you mentioned there might be an easier method in future, related to the progressive sampler?

[Zdravko.Keremidchiev]

Checked out your scene and we practically have the same setup. But different results.

Oliver could you please attach the scene so we could test it as well?

[Mokiki]

Oliver could you please attach the scene so we could test it as well?

Sure but I can't upload the same scene I sent vlado. Because that one isn't available to me right now. But I have the other one which basically has the same issue. Just a slightly different model.

And by the way apoligies for derailing your thread Peter.

[leehumphries]

Sure but I can't upload the same scene I sent vlado. Because that one isn't available to me right now. But I have the other one which basically has the same issue. Just a slightly different model.

And by the way apoligies for derailing your thread Peter.

Just rendered your scene you uploaded and with refractive and reflective GI caustics on glass is fine - not dark

[Mokiki]

@leehumphries.
Disable caustics and you'll see a much brighter version of the glass.

[tashko.zashev]

Hi Oliver,

I got the same render issue in my test renders as well and after some more investigation found that the glass refraction is calculated differently when the multiple importance sampling (MIS) is enabled for the Dome light.
Here are some render results to illustrate the differences:

Actually I'm not sure whether this is a bug or expected behavior, have to discuss it with our developers and probably run a few more tests.

[Lupaz]

Any news on this?
Thanks.

[peterguthrie]

hmmm so could this be the reason i couldn't get my water looking good with 'affect shadows' off ?