[Radiance-general] Size of ground the plane

[Compagnon Raphaël]

Hi

Are you sure you have also modelled the "infinite" ground plane as a glowing source ? This has to be modelled even if you also put a large disk for the ground plane.

Raphaël
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De : Alejandro Pacheco Diéguez [paxeco2205 at hotmail.com]
Envoyé : jeudi 16 octobre 2014 10:36
À : radiance-general at radiance-online.org
Objet : [Radiance-general] Size of ground the plane

Hi all,
I am assessning DF levels in a 4th floor of a building in an unobstructed area, so I am not considering any surrounding building just a ground plane that I modeled as a circle.
Almost by chance I discovered increasing the size of my ground plane has a significant effect on my DF. Using a ground plane of 500m radius I had an average of 3.34%, if I increase it to 1000meters I get over 12%. As long as I understand, this should not have such a big effect, should it? Could I be doing something wrong? Can I do something to make sure I get reasonable values?
I am running the simulation though DIVA for Rhino in Grasshopper. My radiance parameters are: -ab 7 -ad 2048 -as 1024 -ar 256 -aa 0.1. My ground plane reflectance is 0.25.
Thanks in advance,
Alejandro