[Radiance-general] modeling trees in Radiance

[Germán Molina Larrain]

Dear Joe and Greg,

Not sure if this is a question... there it goes though.

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 angle of incidence?? (the percentaje of
specular transmission does no change with different angles of incidence in
a perforated screen)

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?

THANKS

Germán

2015-02-05 8:52 GMT-03:00 Greg Ward <gregoryjward at gmail.com>:

> 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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>
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