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PT or PMC? Tips on less grainy scenes?

Posted: Tue Jun 14, 2016 8:29 pm
by cbaadvertising
Hey guys,
I'm fairly new to Octane, I've been using Pathtracing to render this scene but now I'm wondering if I should use PMC.
My scene is an interior that contains 7 semi transparent layers lit by a couple of lights and an HDRI.

My render time right now is about an hour for ~6500 samples (and pretty grainy). Ideally I'd like the render to be grain-free and under 2 hours (which is why now I'm exploring PMC) but I understand it's also based on my set up, which by the way is 2x GTX980M.
I'm also looking into online render farms, which is another reason I want to get the render under 2 hrs per frame.
---- If anyone can recommend a good GPU renderfarm I'd really appreciate it! ----

Scene: https://drive.google.com/folderview?id= ... sp=sharing

Thanks to any tips and advice in advance!

Re: PT or PMC? Tips on less grainy scenes?

Posted: Wed Jun 15, 2016 12:04 pm
by atome451
Hi cbaadvertising,

Some suggestions:
You should give a compressed file. Downloading each file is boring.
You should add a portal to your window with normals pointing inside and/or use an invisible light panel pointing inside.
As your scene is an interior, you should reduce the path termination power (see doc https://docs.otoy.com/#60Path%20Tracing%20Kernel)
You should give a tickness to your layers if you use a specular material. The result will be far more logical and you will be able to use a real index.
If you don't need very accurate caustics, you should give higher value to the caustic blur.
To speed up the render, you should use bump or mormal map on your specular and not displacement.
You should give more logical parameters to your lights without surface brightness (it strangles the light emission and it's not necessary here i think).

I have tested your file without downloading all textures. I'm curious to test it with textures but i have no time to download then all.

Hope this will help you. I'm sure another users will have more ideas. ;)
Sorry for my poor english...

Re: PT or PMC? Tips on less grainy scenes?

Posted: Wed Jun 15, 2016 2:07 pm
by cbaadvertising
I will try those things now :)

Re: PT or PMC? Tips on less grainy scenes?

Posted: Wed Jun 15, 2016 2:08 pm
by cbaadvertising
atome451 wrote:Hi cbaadvertising,

Some suggestions:
You should give a compressed file. Downloading each file is boring.
You should add a portal to your window with normals pointing inside and/or use an invisible light panel pointing inside.
As your scene is an interior, you should reduce the path termination power (see doc https://docs.otoy.com/#60Path%20Tracing%20Kernel)
You should give a tickness to your layers if you use a specular material. The result will be far more logical and you will be able to use a real index.
If you don't need very accurate caustics, you should give higher value to the caustic blur.
To speed up the render, you should use bump or mormal map on your specular and not displacement.
You should give more logical parameters to your lights without surface brightness (it strangles the light emission and it's not necessary here i think).

I have tested your file without downloading all textures. I'm curious to test it with textures but i have no time to download then all.

Hope this will help you. I'm sure another users will have more ideas. ;)
Sorry for my poor english...
Thanks for the useful info!

PS. Drive usually zips the file when you download a folder!