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can not see light through glass

Posted: Wed Aug 11, 2010 6:10 am
by Gary
Hello,

I have a strip light in the fixture at the back of this image that is visible above the glass at the stairs but is not visible (but should be) through the glass. Attached is also the settings for the glass.

Any help is appreciated.

Thanks,

Gary

Re: can not see light through glass

Posted: Wed Aug 11, 2010 5:32 pm
by tom
Can you replicate this in a new scene using 2 objects?

Re: can not see light through glass

Posted: Wed Aug 11, 2010 5:39 pm
by Gary
Hello Tom,

I can take just the cabinet with the light and the glass railing and get the following results:

1. with no other lights on, I can see the light through the glass
2. if I turn on a sky dome it will wash out seeing the light through the glass (or the cabinet light must be cranked up in value to an extreme output)

I can send a simple MXS if needed.

Thanks,

Gary

Re: can not see light through glass

Posted: Wed Aug 11, 2010 5:53 pm
by tom
Thanks. Please send me this simplified one so, I can precisely say what's going on.

Re: can not see light through glass

Posted: Wed Aug 11, 2010 5:59 pm
by Gary
Hello Tom,

To what email address should I send a MXS?

Thanks,

Gary

Re: can not see light through glass

Posted: Wed Aug 11, 2010 6:11 pm
by tom
tomATnextlimitDOTcom

Re: can not see light through glass

Posted: Wed Aug 11, 2010 6:37 pm
by tom
Seeing something through glass is all about reflection and refraction. Your emitter geometry is hidden from reflections/refractions. Unhide it and it will work. ;)

-edit: I forgot to say you should additionally unhide it from global illumination.

Re: can not see light through glass

Posted: Wed Aug 11, 2010 6:51 pm
by Gary
Great. Can you provide simple explanations for "hidden from camera", "hidden from reflections/refractions" and "hidden from global illumination" relative to regular geometry and emitter geometry?

My current understanding is clearly not good enough to avoid these kinds of situations. For instance, if I want to place an emitter and have it hidden from the camera, and not have the emitter geometry cast shadows, what would be the correct settings.

Thanks for your help.

Gary

-edit- I do think I have a correct understanding of "hidden from camera" :)

Re: can not see light through glass

Posted: Fri Aug 13, 2010 1:04 pm
by tom
Hidden from Camera: Object is not directly visible to camera but, it's still in the scene and visible in reflections/refractions.
Hidden from Reflections/Refractions: Object is visible but it won't appear in reflections (e.g.mirrors) or refractions (e.g.through the glass).
Hidden from Global Illumination: Object is invisible to scene. It means, only the camera can see the object and you may think of it like the opposite of "Hidden from Camera".

Re: can not see light through glass

Posted: Fri Aug 13, 2010 4:45 pm
by Gary
Hello Tom,

Thanks for the explanations. The problem I am having is that given these explanations I would then expect that if I choose all 3 for an emitter object, it will then cast light, not be seen, and not cast shadows. With the simple file attached, both emitter objects have all 3 hidden options selected, but are casting shadows....

Thanks for any insight.

Gary

Re: can not see light through glass

Posted: Fri Aug 13, 2010 5:03 pm
by tom
Please check this tutorial:
http://think.maxwellrender.com/invisibl ... ers-7.html

You only need to check "Hidden from camera" and add a ghost BSDF to emitter material.

Re: can not see light through glass

Posted: Fri Aug 13, 2010 6:18 pm
by Gary
Good, thanks.

Gary