View Full Version : lighting a cloudy day with MR

12 December 2010, 01:49 PM
hi, i often use max daylight system with mr sun & sky to render
exterior shots. its accurate for sunny days, but i was wondering whats
the best way to make cloudy days, where you still get some direct light
when the sunlight get through some clouds, but the lighting isnt as
strong, and shadows are much more smooth. also, you get much more
indirect lighting because of the rays that scatter through the clouds.

so what would be the best way to simulate that?

thanks in advance

12 December 2010, 03:31 AM
i would have thought the best way would be to go for a more manual set up utilizing ambient occlusion. you could have a direct or spot light with shadows reduced and blurred to simulate a soft sunlight while at the same time overlaying a good soft ambient occlusion pass for indirect lighting

01 January 2011, 06:12 PM
Hey Rafael. I was recently trying to do the same thing. I was integrating a character in a photograph with an overcast sky. I used the sun/sky shader for mental ray and found that there is an option for "soft shadows". It is located under the physical sun node. Try playing with it and see what you can come up with. It seemed to work well, and gave results similar to using an area light. My shadow pass shows a sharp outline where objects are close to each other, and a nice diffusion when further away. The result is actually a lot like ambient occlusion, though in my scene, the sun was almost directly overhead.

Let me know if it works out.

01 January 2011, 10:40 AM
also maybe try adding a noise shader as a gobo and play around with the settings . it might break up the light and give the impression of clouds.

01 January 2011, 02:30 AM
yeah, what worked for me was playing with sun intensity and skylight intensity, aswell as softening direct shadows.

thanks guys

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