The generation of pixels behind a glass

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tomas_p
Licensed Customer
Posts: 188
Joined: Sun Mar 14, 2010 7:38 pm
Location: Slovakia

Hi Radiance.

I did few tests with specular material as windowpane.
The generation of pixels behind a glass in interior is slowing down with time and the noise is not improving with time. Everything is rendered smoothly, except interior behind a glass. After 3 hours of redndering, the noise is still significant (two windowpanes 3,5h and 1 windowpane is faster bat not without noise). Do you have some tips, how to improve rendering scenes with glass windows?
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GeForce GTX 260 ,one layer of glass, 27min
GeForce GTX 260 ,one layer of glass, 27min
GeForce GTX 260 ,two layers of glass, 3,5 h
GeForce GTX 260 ,two layers of glass, 3,5 h
Win Vista 64 | Phenom II X4 905e |Gigabyte GTX690 and zotac Geforce GTX260 | 8GB
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Sam
Licensed Customer
Posts: 1012
Joined: Mon Jan 11, 2010 10:06 am
Location: Geneva
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That's because there's no MLT in Octane currently
You are basically lighting the inside with caustics
That's why its so slow :lol:

Wait for MLT and light portals and all will be OK both outside and inside ;)
http://Kuto.ch - Samuel Zeller - Freelance 3D Generalist and Graphic designer from Switzerland
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radiance
Posts: 7633
Joined: Wed Oct 21, 2009 2:33 pm

Hi,

This is all related to the same issue.
I'll describe it here once, and if people notice other posts about the same question, please link to this post.

Rendering interiors with glass windows, or exteriors with views inside buildings with glass windows is very slow/noisy.

This is because you are lighting your inside of the house with a caustic.
The light is refracted 2x through the double sided glass windows,
and this is very innefficient.

Unbiased render engines have several techniques to make this more efficient, each one adds a lot to the efficiency,
and having them all together gives very fast render times/efficiency.

Since octane is still quite young, and it's not easy to develop these techniques quickly on a GPU platform,
we don't have much of them yet, so you will just have to let them render a little longer for now.
In any way, octane's raw speed makes the render time equal to a well mature unbiased renderer with these techniques,
eg try rendering an interior with a CPU unbiased renderer with architectural glass, portals and MLT and you will also have to wait 3-4 hours.

Here's a few techniques and approximately when they will be made available in octane:

- MLT - beta3
- portals - probably beta3 aswell, otherwise beta4
- architectural glass - i will try to squeeze it into beta2, if time permits, otherwise beta3.

Thanks,
Radiance
Win 7 x64 & ubuntu | 2x GTX480 | Quad 2.66GHz | 8GB
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