[Radiance-general] modeling trees in Radiance

[Germán Molina Larrain]

Dear Joe and Greg,

I was trying to emulate a micro perforated metal the other day (I do not
want to draw thousands of little holes!)... I tried to use TRANS equations
to derive the parameters I needed, but it did not seem to work. I think
TRANS properties vary with the ngle of incidence??

I ended up using a mixture between VOID and a Plastic material, on which I
varied the percentage of "Void"... I am not sure, maybe that trick would
also help modelling trees.

Am I correct? Is, what I did, legally from the physical laws of lighitng?
Hi Joe,

If you want to model your tree as a sphere (on a stick?) with a certain
transmittance, the "trans" material type should suit your purpose.
Parameter setting is a bit tricky, but since you don't have any reflection
or scattering to consider, simply set values according to your
transmittance T:

void trans treeT
0
0
7 T T T 0 0 1 1

I hope this addresses your question.

Best,
-Greg

*From: *Joe Smith <the.oat.cracker at gmail.com>

*Subject: *[Radiance-general] modeling trees in Radiance

*Date: *February 5, 2015 3:41:24 AM EST


 Dear list,

May I ask advices on modeling trees in a Radiance scene?

Suppose I can get a so-called "*transmittance coefficient*" value for a
given type of tree through field measurement and then calculating the
average ratio of the irradiance below a tree to that above it for multiple
points below a tree under various types of sky conditions, what *surface
parameter * can I specify in Radiance for a simplified sphere surface
representing a tree that can use this "transmittance coefficient" as a
reference for simulation to understand the impact of the tree to the
surrounding environment in terms of shading?

Hope I explain myself clearly ...

Thanks!


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