Surface Error Properties with Honeybee Radiance Materials

Hi everyone,

I am trying to implement a forward ray tracing algorithm in grasshopper to perform an evaluation of a building integrated concentrated solar application. I have taken a look at the discussion regarding the ladybug forward ray tracer component (which it seems is probably a little too simplistic for the analysis I am trying to do) and the discussion regarding photon mapping with radiance (though I am not entirely sure how this works):

http://www.grasshopper3d.com/video/ladybug-forward-ray-tracing-new-...

http://www.grasshopper3d.com/group/ladybug/forum/topics/photon-map-...

http://www.radiance-online.org/community/workshops/2015-philadelphi...

What I am wondering is if there is a way to implement some sort of surface error property in honeybee radiance materials that determine the degree of deviation from specular reflection for a ray of light (see the picture below to get an idea of what I mean). The main goal of my analysis is to estimate the achievable concentrations as a function of surface error so having these material properties is quite vital. Would be great to hear if anyone has any insights on how I could go about solving this problem.