ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/radiance/ray/src/gen/skybright.cal
Revision: 1.1
Committed: Thu Aug 22 08:49:44 1991 UTC (32 years, 7 months ago) by greg
Branch: MAIN
Log Message:
Initial revision

File Contents

# Content
1 { SCCSid "$SunId$ LBL" }
2
3 {
4 Sky brightness function for sunny and cloudy skies.
5
6 6/6/86
7
8 Additional arguments required for calculation of skybright:
9
10 A1 - boolean, positive for cloudy sky
11 A2 - zenith brightness
12 A3 - ground plane brightness
13 A4 - normalization factor based on sun direction
14 A5,A6,A7 - sun direction
15 }
16
17 skybright = wmean((Dz+1.01)^10, if(A1, cloudysky, sunnysky),
18 (Dz+1.01)^-10, A3);
19
20 wmean(a, x, b, y) = (a*x + b*y) / (a + b);
21
22 cloudysky = A2 * (1 + 2*Dz) / 3;
23
24 sunnysky = A2 * (.91 + 10*exp(-3*gamma) + .45*cosgamma*cosgamma)
25 * if( Dz - .01, 1.0 - exp(-.32/Dz), 1.0) / A4;
26
27 gamma = Acos(cosgamma);
28
29 cosgamma = Dx*A5 + Dy*A6 + Dz*A7;