lens,genbsdf,lightpipe

Hi;I'm using Grasshopper-Honeybee to model a light pipe using three phase simulation method. and i need to model lens and prismatic surface for my light pipe but i think Honeybee is not able to do that. so i modeled the prismatic surface in honeybee and exported geometry and material rad file and generated .xml file using genbsdf,exe via command prompt to convert .rad file to .xml...my questions is that my process is true? and the material must be just dielectric for acting like prism or lens? and the last question is that in my process using genprism.exe in unnecessary?
thanks,

Hi Davood,

I am afraid that this is not going to work. You can model a lens with dielectric, if you ensure sufficiently high resolution of your mesh. That will work if you "look through it" in Radiance. But if you want it to use it e.g. in illuminance calculations below your light pipe or see the redistributed light on a diffuse surface, you would have to use the photon map. You find an example here, where I tried to avoid tesselated surfaces to create "perfect" spherical lenses:

The BSDF modifier will not help you here. The BSDF in Radiance describes an average over the surface you apply it to. A lens works different, it matters wether your ray hits it in the center or on the edge, otherwise it will not work.

About the light-pipe, you may do that with rfluxmtx. But maybe this is just one more reason to look into the photon map.

Cheers,
Lars.

···

Hi;
I'm using Grasshopper-Honeybee to model a light pipe using three phase simulation method. and i need to model lens and prismatic surface for my light pipe but i think Honeybee is not able to do that. so i modeled the prismatic surface in honeybee and exported geometry and material rad file and generated .xml file using genbsdf,exe via command prompt to convert .rad file to .xml...my questions is that my process is true? and the material must be just dielectric for acting like prism or lens? and the last question is that in my process using genprism.exe in unnecessary?
thanks,

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