PBR difuse bounces and glass

[andreu.lucio]

Hi all!

I can´t get the difuse bounces work in objects inside another object with default glass material. It´s posible to get it working in some way?

I will try to make it in comp but I have all the scene working very well rendering all together and would be very nice to get that efect to.

Please some help from the pros, just wanted to know if it´s posible or not.

I have looked many topics but haven´t found nothing about this.

Thanks in advance!

PBR_glass.hipnc

Edited May 28, 2010 by putoparri

[DaJuice]

Right now you've got "faux caustics" enabled on your glass, which is why you're getting any light on the stuff inside the glass at all. To get more physically accurate results we have to use caustics to illuminate objects inside the glass. Typically you would use photon maps, but for the life of me I couldn't get them to work in this example. Another option is to use raytraced caustics. For that you have to add the vm_pbrpathtype parameter to mantra (little gear icon > Edit Rendering Parameters). When you set it to All Paths mantra will do raytraced caustics, albeit, very slowly and it requires lots of samples. Larger area lights look better.

[rant] Is it just me or are photon maps a total crapshoot most of the time? I really hope SESI is working on faster raytraced caustics for PBR [/rant]

[andreu.lucio]

Hey! Thanks very much DaJuice for your answer, it helped me a lot. A virtual paulaner for you!

So after trying to increase the samples to get a smooth result I think I will try another way.

Do you know if its posible to have one object iluminating with a constant material but not visible in the reflections?.

From what I´m getting I think that it´s imposible with the PBR but maybe you know the way.

I have to fake the indirect lighting inside (just like an ambient light,no need off real and expensive caustics) in some way but with normal render times (with PBR are quite long yet).

Writing this I just imagine a simple way that I think it´s going to work. An environment light only afecting the object inside. I´m going to try it rigth now.

Again, thanks a lot DaJuice!

[andreu.lucio]

After trying somethings without succes I made the way you say with longer render times (15 mins,which is not so bad, at least for this project).

Here it is how its rigth now.

[DaJuice]

Hay putoparri, that's looking really nice. Materials look great.

From playing around a bit it seems like excluding a self-illuminating object from the Reflection Mask also takes away it's light contribution to that object.

[andreu.lucio]

Hey, Thanks again!

Yes, looks like in PBR the reflection and ilumination rays can´t be separated. Hope that this changed in H11.

Well I just finished this work, it´s just a scientific visualization so the look it´s not so important but I like to learn and try to improve my skills in every project. The animation and cameras are very simple.

I used the parameter you told me and was fine so thank again for the tip!