[Radiance-general] Trees

[Tim Perry]

Greg,

My mistake was taking the simple average, rather than the photopic average, right? I looked right past that adjective....

Thanks for catching my error,
Tim



----- Original Message -----
From: Gregory J. Ward <gregoryjward at gmail.com>
To: Tim Perry <perry2of5 at yahoo.com>
Cc: "radiance-general at radiance-online.org" <radiance-general at radiance-online.org>
Sent: Tuesday, December 6, 2011 5:32 PM
Subject: Re: [Radiance-general] Trees

Hi Tim,

The roughness will influence any transmitted specular component as well.

Your calculation of trans parameters is off because your Rd is not 40% using RGB of 25%, 70% and 25%.  If you want 40% reflectance, you need to adjust the RGB to (0.181,0.508,0.181).  I computed these based on the Y function in "ray/src/cal/cal/xyz_rgb.cal".

With these changes, I get:

void trans TransTreeMat
0
0
7 0.272 0.761 0.272 0 0 0.33333 0.05

Does this make sense?

-Greg

> From: Tim Perry <perry2of5 at yahoo.com>
> Date: December 6, 2011 12:31:15 PM PST
> 
> Dear Greg,
> 
> Does the surface roughness matter if the reflected specularity (Rs) is zero? 
> 
> Thanks,
> Tim
> 
> PS: Is there a Radiance beginners list? I surely belong there.
> PPS: Here is my full definition. I'm using pages 325-326 in Rendering With Radiance as my guide.
> 
> Diffuse reflectance (Rd = 40%)
> Red: 25%Cr
> Green: 70%Cg
> Blue: 25%Cb
> 
> Reflected Specularity (Rs): 0
> 
> Surface Roughness (Sr): 0.0
> 
> Diffuse Transmissivity (Td) = 19%
> 
> Transmitted Specularity (Ts) = 1%
> 
> ** Final Material **
> void trans TransTreeMat
> 0
> 0
> 7 0.375 1.05 0.375 0 0 0.33333 0.05