ray/lib/tim1.cal

{
        Calculate BRTDF of Transparent Insulation Materials
        made up of many small tubes packed tightly together.

        29 Nov 1991     Greg Ward and Raphael Compagnon
        06 Feb 1995     Updated for Radiance 2.4 by Greg Ward

        Apply with following BRTDfunc:

        mod BRTDfunc tim1
        10      0       0       0
                stran   stran   stran
                brtdf   brtdf   brtdf
                tim1.cal
        0
        12 0 0 0 0 0 0 0 0 0 R T K

        where:
                R = diffuse reflectance when Ktan_t is zero
                T = total transmittance
                K = ratio of tube length to diameter
}

Ktan_t = arg(12) * Sqrt(1-RdotP*RdotP)/RdotP;

stran = if(1-Ktan_t, 2/PI*Acos(Ktan_t) - Ktan_t/PI*Sqrt(1-Ktan_t*Ktan_t), 0);

brtdf(lx,ly,lz) = if(lx*NxP+ly*NyP+lz*NzP, arg(10), arg(11)/(1-arg(10)))
                        * (1-stran)/PI;
Revision:	1.2
Committed:	Tue Mar 18 17:30:17 2003 UTC (21 years, 2 months ago) by greg
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.1:	+0 -0 lines
State:	*FILE REMOVED*
Log Message:	Decided to move ray/lib directory into non-CVS distribution
#	Content
1	{
2	Calculate BRTDF of Transparent Insulation Materials
3	made up of many small tubes packed tightly together.
4
5	29 Nov 1991 Greg Ward and Raphael Compagnon
6	06 Feb 1995 Updated for Radiance 2.4 by Greg Ward
7
8	Apply with following BRTDfunc:
9
10	mod BRTDfunc tim1
11	10 0 0 0
12	stran stran stran
13	brtdf brtdf brtdf
14	tim1.cal
15	0
16	12 0 0 0 0 0 0 0 0 0 R T K
17
18	where:
19	R = diffuse reflectance when Ktan_t is zero
20	T = total transmittance
21	K = ratio of tube length to diameter
22	}
23
24	Ktan_t = arg(12) * Sqrt(1-RdotP*RdotP)/RdotP;
25
26	stran = if(1-Ktan_t, 2/PIAcos(Ktan_t) - Ktan_t/PISqrt(1-Ktan_t*Ktan_t), 0);
27
28	brtdf(lx,ly,lz) = if(lxNxP+lyNyP+lz*NzP, arg(10), arg(11)/(1-arg(10)))
29	* (1-stran)/PI;