Chris,
Again the number of curves which SubCrv gives me is different from the actual curve on the surface! for example it gives me 80 curves in which there are 20 curves!
e able to loft them correctly. picked a point on the curve, decomposed points, selected x-output. but how to arrange the curves now from -n to +n?
cause my list looks like: -90,-80,-70,10,20,30,-60,-50,-40,40...
im so sorry but i have no idea, and unfortunately no time :(
thx in advance
michael…
exact formula is inside /lib/skybright.cal if this can help you to find the name.
{ RCSid: $Id$ } { Sky brightness function for sunny and cloudy skies.
Additional arguments required for calculation of skybright:
A1 - 1 for CIE clear, 2 for CIE overcast, 3 for uniform, 4 for CIE intermediate A2 - zenith brightness A3 - ground plane brightness A4 - normalization factor based on sun direction A5,A6,A7 - sun direction }
cosgamma = Dx*A5 + Dy*A6 + Dz*A7;
gamma = Acos(cosgamma); { angle from sun to this point in sky }
zt = Acos(A7); { angle from zenith to sun }
eta = Acos(Dz); { angle from zenith to this point in sky }
wmean(a, x, b, y) : (a*x + b*y) / (a + b);
skybr = wmean((Dz+1.01)^10, select(A1, sunnysky, cloudysky, unifsky, intersky), (Dz+1.01)^-10, A3);
sunnysky = A2 * (.91 + 10*exp(-3*gamma) + .45*cosgamma*cosgamma) * if( Dz - .01, 1.0 - exp(-.32/Dz), 1.0) / A4;
cloudysky = A2 * (1 + 2*Dz)/3;
unifsky = A2;
intersky = A2 * ( (1.35*sin(5.631-3.59*eta)+3.12)*sin(4.396-2.6*zt) + 6.37 - eta ) / 2.326 * exp(gamma*-.563*((2.629-eta)*(1.562-zt)+.812)) / A4;
…
0.533000void brightfunc skyfunc2 skybright perezlum.cal010 1.382e+00 3.201e-01 1.066879 -0.754821 0.015485 -0.048998 -0.089403 0.066341 -0.860010 0.505947
The values in bold are then evaluated using the equations in the file perezlum.cal inside the RAYPATH directory in Radiance..
{ All-weather Angular Sky Luminance Distribution . Additional arguments required for calculation of skybright: A1 - diffus normalization A2 - ground brightness A3,A4,A5,A6,A7 - coefficients for the Perez model A8,A9,A10 - sun direction}skybright = wmean((Dz+1.01)^10, intersky, (Dz+1.01)^-10, A2 );wmean(a, x, b, y) = (a*x+b*y)/(a+b);intersky = if( (Dz-0.01), A1 * (1 + A3*Exp(A4/Dz) ) * ( 1 + A5*Exp(A6*gamma) + A7*cos(gamma)*cos(gamma) ), A1 * (1 + A3*Exp(A4/0.01) ) * ( 1 + A5*Exp(A6*gamma) + A7*cos(gamma)*cos(gamma) ) );
This data is then mapped to the "glow" material that represents the celestial hemisphere...You can edit the climate based sky produced by Honeybee and enter your own values. The other option would be to just use gendaylit from DOS Prompt.…