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hiding a ceiling

Posted: Fri Aug 13, 2010 4:52 pm
by jnoftle123
im doing a interior scene from a top down view, how would i go about hiding the ceiling from the camera, but having it there for the light to bounce around in?
similar to this view. would anyone have any ideas of how to achieve this in octane
http://www.westcoastillustration.com/im ... 24_big.jpg

Thanks,

Re: hiding a ceiling

Posted: Fri Aug 13, 2010 9:00 pm
by gristle
This is what you need single sided polygons for. Mentioned it a long time ago, I think the response was there is a slim chance it might be added.

Re: hiding a ceiling

Posted: Fri Aug 13, 2010 9:12 pm
by [gk]
using the largest possible range for the AO pass you can get very close to the images look refferenced with no ceeling mesh

Re: hiding a ceiling

Posted: Sat Aug 14, 2010 5:38 am
by jbeau3d
I haven't tried this in octane but it should work. Make the ceiling specular, 100% white, turn all other settings to 0 and change IOR to 1.0(air), then increase the bounces until it completely disappears. This should give you the desired look; you could also do a seperate AO pass and multiply it in with curves/level tweaks for contrast, as [gk] mentions. I would be more interested in a true ambient pass.

Now if I could get some documentation on the way an *.osc file is structured then I could write a Perl script that would parse a file and swap out all your materials to something specific. This would be ideal for all kinds of custom passes like mattes, object ID's, mat ID, custom AO, etc.

Re: hiding a ceiling

Posted: Wed Aug 18, 2010 11:25 pm
by jbeau3d
Tested the IOR trick and it doesn't work as expected; due to artifacting. Make the opacity 0% on your ceiling material and that will work.