Best way to achieve this light effect?

[FrankGehry]

I'm trying to create a room with a naturally-lit ceiling (example image at bottom—Museum Brandhorst). To do this, I'd like to utilize glass skylights that are frosted to create a soft white light. The scene is being lit by and HDRI sky. I have a frosted glass plugged in, but my shadows still seem rather sharp.

I'm looking for suggestions on how I should alter the material to get softer light. I tried to upload my material file, but it keeps telling me it's invalid.

I appreciate any help!

[Neilg]

I would fake this - instead of glass change to a 2-sided material which does not cast shadows, and under each panel place a rectangular vray plane light. To make light diffuse like that properly is outrageously slow.

[FrankGehry]

I would fake this - instead of glass change to a 2-sided material which does not cast shadows, and under each panel place a rectangular vray plane light. To make light diffuse like that properly is outrageously slow.

Can you go into more detail about how the material would be composed? Would it simply be like one-way glass so from inside, you could see out, but no sunlight would be allowed through?

[cheerioboy]

https://docs.chaosgroup.com/display/...+VRay2SidedMtl
You'd put a plain vray material into the 2-sided, with a white diffuse. And then add a vray light just below it, inside the room, if necessary to fake more light entering.


Attached an example render - I used the same material from the walls, dropped it into a 2-sided material and adjusted the translucency

[FrankGehry]

https://docs.chaosgroup.com/display/...+VRay2SidedMtl
You'd put a plain vray material into the 2-sided, with a white diffuse. And then add a vray light just below it, inside the room, if necessary to fake more light entering.


Attached an example render - I used the same material from the walls, dropped it into a 2-sided material and adjusted the translucency

Thank you for taking the time to help me! If possible, do you mind uploading that SU file?

[cheerioboy]

Sorry I whipped it up in 3dsmax - sketchup does have the 2-sided material, https://docs.chaosgroup.com/display/...+%7C+Mtl2Sided
just put a regular material in as the front material, and blank for the 2nd, then adjust translucency as needed. apply to a single plane of geometry (no thickness), normals facing into the room (although it might not matter)
Hope that helps.

[FrankGehry]

Sorry I whipped it up in 3dsmax - sketchup does have the 2-sided material, https://docs.chaosgroup.com/display/...+%7C+Mtl2Sided
just put a regular material in as the front material, and blank for the 2nd, then adjust translucency as needed. apply to a single plane of geometry (no thickness), normals facing into the room (although it might not matter)
Hope that helps.

No worries! I think I had it close. I like how yours has that neutral white tone to it. Mine kept having a warmer yellowish tone. Perhaps it's due to the hdri sky I'm using to light the scene. Thanks for explaining the material in more detail. I think it's the translucency variable I'm not doing. Your email referring to the translucency settings under 'refraction' right?

[cheerioboy]

It looks like your light in general is yellow - you might want to look at your camera's white balance to get the light more neutral.
The translucency settings I was mentioning is in the 2-sided material, not in the vray material that goes in the 2-sided material. It looks like in sketchup there's a slider to adjust the translucency. Look at the link I sent earlier that explains the 2-sided material.