Subsurface Scatter Question

[sldstt]

Hi, I'm playing around with a subsurface scatter, but seems like I'm missing something.

My scene is just a flat subsurface material wall with no texture. the only light source is a spot light which produces a small spot on the wall. My expectation was that with enough samples I should be able to reconstruct the diffusion profile for this material, but no matter what parameters I'm using (mean free path and reflectance), I get the same result, just a few lit pixels and that's it.

What am I doing wrong here?

Thanks

[Matt Pharr]

Can you post the scene?

Thanks,

Matt

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[sldstt]

Sure, here it is. I took the mfp values from the "head" scene for no particular reason. 

I'm illuminating the wall with a small spot, but changing these parameters doesn't seem to have any effect.

Thanks

LookAt 0 0 0

0 0 1

0 1 0

Camera "perspective"

"float fov" [1]

Sampler "halton" "integer pixelsamples" 256

Integrator "volpath"

Film "rgb" "string filename" "wall_ss.exr"

"integer xresolution" [200] "integer yresolution" [200]

WorldBegin

LightSource "spot"

"rgb I" [1 1 1 ]

"float coneangle" [0.03]

"float conedeltaangle" [.01]

"point3 from" [0 0 0]

"point3 to" [0 0 1]

AttributeBegin

Material "subsurface"

"bool remaproughness" [ false ]

"float vroughness" [ 0.01 ]

"float uroughness" [ 0.01 ]

"float eta" [ 1.33 ]

"rgb reflectance" [0.2 0.2 0.2]

"rgb mfp" [ 0.0012953 0.00095238 0.00067114 ]

Shape "disk"

"float height" [.001]

"float radius" [100]

AttributeEnd

[sldstt]

update: looks like using "skin1" or "skin2" I can get some visible SSS effects. Am I setting the mfp/reflectance paramters wrong?