[Radiance-general] modeling trees in Radiance

[Joe Smith]

Dear all, thank you very much!

To Greg: May I ask, if I also want to consider reflection or scattering of
the sphere surface, how should I specify the parameters for the trans type
of material? and what does the "trans" parameter for trans material means?

To German: Thank you for the tip of using a mixfunc! Can you advise on how
to specify the funcfile to define the pattern and proportion of mixing of
void and plastic materials?

To Compagnon: Thank you for the square-root reminder!

To Christopher and Greg: Thanks for the tip on mist! Can we imagine the
tree object modeled in this way as a hollowed sphere whose surface is
composed of a texture with an "alternating void and plastic" pattern, and
the inside of the sphere is filled with a lump of "mysterious" fog ...?


On Fri, Feb 6, 2015 at 8:14 AM, Greg Ward <gregoryjward at gmail.com> wrote:

> Yes, I should have thought about the square root -- good catch!
>
> The trans type doesn't change with incident angle (unlike glass or
> dielectric), which is part of why I suggested it.  I don't know what's
> happening in Germán's case, but using a mixfunc with void and plastic is a
> perfectly acceptable approach.
>
> As for varying the absorption using mist, a ball of mist might indeed have
> the desired behavior, as the absorption is an exponential function of the
> volume traversed using the mist material.
>
> Cheers,
> -Greg
>
> *From: *Christopher Rush <Christopher.Rush at arup.com>
>
> *Subject: *Re: [Radiance-general] modeling trees in Radiance
>
> *Date: *February 5, 2015 7:05:02 AM PST
>
>
>    I see Raphaël just pointed out what I was in the middle of typing
> about the square root transmittance correction. Also, keep in mind this
> will only be a very rough approximation for any measurements very near the
> tree, where rays passing through all parts of the tree get the same
> reduction even if they just glance the fringe of the sphere or other shape.
> In reality, rays passing through the outer fringes of a tree canopy would
> intersect with fewer leaves than those passing through the more substantial
> core of the tree (also depending on tree species).
>
> I would love to here if anyone has a more ideal solution for modeling
> trees that is relatively accurate, and reasonable in terms of rendering
> time and use of RAM – in other words without modeling every single leaf. If
> it looked nice that would be a bonus. Is this a possible application for
> something exotic like mist? I’ve never even investigated mist so apologies
> if that’s a ridiculous suggestion.
>
>
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>
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