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DangerousCliff
12-15-2006, 09:49 PM
Afternoon all,

I'm having trouble getting decent (well, anything approaching decent) results from using the new MR daylight system with SSS fast skin.

using: correct scene scale, a MR daylight system for my key, a Photometric area for a fill, FG: draft, log exposure for external daylight, and a A&D mr material set to matte and 80% white comes out fine, looks like what i would expect- however, just putting a sss fast skin (with default settings) renders out an unsightly uniformly 90% black.

i've been reading helpfiles and references all morning, and still haven't come up with a solution. i'm able to do exactly what i want with standard MR lights, however, i'm trying to move toward using a photometric workflow.

has any one else run into this? am i doing something completely dumbth? have i missed the "make it work" checkbox?

thanks all,
MasterZap
12-18-2006, 03:04 PM
If you "spent time" in the documentation, how did you miss this notice? ;)

Using Sun & Sky with SSS Materials



To use a mental ray fast SSS material (http://forums.cgsociety.org/subsurface_scattering_sss_materials.html) together with the high-dynamic range Sun & Sky solution, be sure to turn on Scatter Indirect Illumination on the material's Advanced Options rollout so that the material can scatter the skylight, which is considered indirect.

Also, turn off Screen (Soft) Compositing Of Layers, also on the Advanced Options rollout; otherwise the output of the SSS shaders is clamped to a low dynamic range and will appear to render black.





Also, due to an issue in the "new" final gathering techniqies vs. the lightmapping used in the SSS shader, you may need to check the box in the "Final Gathering" section labeled "Use Radius Interpolation (Instead of num FG points)" and set both a min- and max- radius in pixels at 15-ish pixels.


/Z
DangerousCliff
12-18-2006, 04:32 PM
i really hate it when i do something dumb- like somehow completely miss that note in a helpfile i looked at at least three times...

sorry for the trouble, but thanks for the help.
Andy-Murdock
01-02-2007, 09:55 AM
You can also use the MR Sun Sky without logarithmic exposure. Turn down the sun and sky multipliers to 0.02 to get it back to a normal illumination level. This works with SSS.

Andy
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