[Radiance-general] Simple separation of the sky dome
Aris Tsangrassoulis
[email protected]
Thu, 18 Apr 2002 13:24:20 +0300
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Dear Darren,
maybe the following .cal file would be useful to you. Bassicaly is a =
modification of skybright.cal and can by used in the same way.
{ patch.cal
modification of skybright.cal. It's been used to turn on one patch of =
the sky.=20
A liitle axtra effort is needed to create a discrete grid on the sky.=20
Dr. Aris Tsangrassoulis, 1999}
skybr =3D wmean((Dz+1.01)^10,select(A1, sunnysky, cloudysky, unifsky, =
intersky),(Dz+1.01)^-10, A3);
wmean(a, x, b, y) =3D (a*x + b*y) / (a + b);
sunnysky =3D A2 * (.91 + 10 * EXP(-3 * gamma) + .45 * cosgamma * =
cosgamma)* if( Dz - .01, 1.0 - exp(-.32/Dz), 1.0) / A4;
cloudysky =3D A2 * (1 + 2*Dz)/3;=20
dektis1=3Dif(inside( 0 ,azim, 12 ),1,0); {azimuth from 0 to 12 degrees}
dektis2=3Dif(inside( 0 ,eta, 12 ),1,0); {elevation from 0 to 12 =
degrees}
unifsky=3Dif(and(dektis1,dektis2),100,0); {the patch is turned on}
azi=3Datan2(Dx,Dy)*180/3.141592;
azim=3Dif(Dx,azi,azi+360);
intersky =3D 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;
cosgamma =3D Dx*A5 + Dy*A6 + Dz*A7;
gamma=3Dacos(cosgamma);
zt=3Dacos(A7);
eta=3D(1.5707-acos(Dz))*180/3.141592;
Please take into account that the existence of the patch can be verified =
by using the intereflection part of the calculation.
Regards,
Dr. Aris Tsangrassoulis
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<DIV><FONT face=3DArial size=3D2>Dear Darren,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>maybe the following .cal file would be =
useful to=20
you. Bassicaly is a modification of skybright.cal and can by used in the =
same=20
way.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#ff0000 size=3D2>{ =
patch.cal</FONT></DIV>
<DIV><FONT face=3DArial color=3D#ff0000 size=3D2>modification of =
skybright.cal. It's=20
been used to turn on one patch of the sky. </FONT></DIV>
<DIV><FONT face=3DArial color=3D#ff0000 size=3D2>A liitle axtra effort =
is needed to=20
create a discrete grid on the sky. </FONT></DIV>
<DIV><FONT face=3DArial color=3D#ff0000 size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial color=3D#ff0000 size=3D2>Dr. Aris =
Tsangrassoulis,=20
1999}</FONT></DIV>
<DIV><FONT face=3DArial size=3D2><FONT size=3D2>
<P><FONT color=3D#ff0000>skybr =3D wmean((Dz+1.01)^10,select(A1, =
sunnysky,=20
cloudysky, unifsky, intersky),(Dz+1.01)^-10, A3);</FONT></P>
<P><FONT color=3D#ff0000>wmean(a, x, b, y) =3D (a*x + b*y) / (a + =
b);</FONT></P>
<P><FONT color=3D#ff0000>sunnysky =3D A2 * (.91 + 10 * EXP(-3 * gamma) + =
.45 *=20
cosgamma * cosgamma)* if( Dz - .01, 1.0 - exp(-.32/Dz), 1.0) / =
A4;</FONT></P>
<P><FONT color=3D#ff0000>cloudysky =3D A2 * (1 + 2*Dz)/3; </FONT></P>
<P><FONT color=3D#ff0000>dektis1=3Dif(inside( 0 ,azim, 12 ),1,0); =
<STRONG>{azimuth=20
from 0 to 12 degrees}</STRONG></FONT></P>
<P><FONT color=3D#ff0000>dektis2=3Dif(inside( 0 ,eta, 12 ),1,0); =20
<STRONG>{elevation from 0 to 12 degrees}</STRONG></FONT></P>
<P><FONT color=3D#ff0000>unifsky=3Dif(and(dektis1,dektis2),100,0); =
<STRONG>{the=20
patch is turned on}</STRONG></FONT></P>
<P><FONT color=3D#ff0000>azi=3Datan2(Dx,Dy)*180/3.141592;</FONT></P>
<P><FONT color=3D#ff0000>azim=3Dif(Dx,azi,azi+360);</FONT></P>
<P><FONT color=3D#ff0000>intersky =3D A2 * (=20
(1.35*sin(5.631-3.59*eta)+3.12)*sin(4.396-2.6*zt)+ 6.37 - eta ) / 2.326=20
*exp(gamma*-.563*((2.629-eta)*(1.562-zt)+.812)) / A4;</FONT></P>
<P><FONT color=3D#ff0000>cosgamma =3D Dx*A5 + Dy*A6 + Dz*A7;</FONT></P>
<P><FONT color=3D#ff0000>gamma=3Dacos(cosgamma);</FONT></P>
<P><FONT color=3D#ff0000>zt=3Dacos(A7);</FONT></P>
<P><FONT =
color=3D#ff0000>eta=3D(1.5707-acos(Dz))*180/3.141592;</FONT></P>
<P><FONT color=3D#ff0000></FONT> </P>
<P>Please take into account that the existence of the patch can be =
verified by=20
using the intereflection part of the calculation.</P>
<P>Regards,</P>
<P>Dr. Aris Tsangrassoulis</P>
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