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These objects all reflect light in a wide range of directions from the surface. This means there they won't be shiny or reflective, which requires something like LamaConductor to add shininess and reflectivity.

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Diffuse roughness is how you would simulate a powdery surface like dried clay or dust.  When roughness is 0.0,  LamaDiffuse uses the Lambertian model to calculate the diffuse response.  When roughness is > 0.0, the Oren Nayar model is used instead.

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