Lighting / render settings

[david.s]

I have a question to pose. How do you light "top-down" 3d flooplans using mental Ray lighting. No daylight system can be used and there is no ceiling. There should be ambient lighting with light spill into rooms from windows.

I know using light portals are an option but with shadows active they take too long to render (8 hours +). Same with mr omnis set to area light. Any suggestions for high quality but fast (4 hours or less) renders.

Thanks.

[Peter M. Gruhn]

I'm clawing my way up this path too.

 

Threw this together just now. Rendered in 22 minutes with default GI and Medium FG. One MR Daylight system, six portals and a single poly thick ceiling not visible to camera. Couple months ago I did a larger apartment with some interior areas unreachable by daylight. Stuck photometric free lights in those areas and set them a little orange. My machine is no great shakes.

[postite]

Why not using a Skylight ??

[david.s]

I currently use the skylight. My issue is how to create light splash through windows, patio doors, etc with soft area shadows that don't take over 6 hours to render. I used to use a rectangular vray light which created the right effect and didn't take long to render.

But how to achieve same quality/speed ratio with mental ray lighting. Sky portals add subtle lighting to the room but not enough light splash on floors without high values. Bright sky portals then burn out the window frames and cills, and if you reduce the burn setting in photographic exposure control it reduces highlights across the whole image. Any suggestions.

[postite]

I often use skylight with sky portals and don't have these problems. With linear exposure, and sky portal multi like 5-6. And sky portals in front of the frames, inside the room and something like 15cm above the ground (1st img).

 

Or you can simply use an invisible plane with self illumination and "Illuminates the scene" ticked. (img 2).

 

You can also untick "Receive illumination from final gather" in an object's Mental ray properties to avoid too much burn.

 

I hope it helps. Or post a render to show your problems.

Edited November 16, 2010 by postite