/usr/share/radiance/veil.cal is in radiance-materials 4R0+20110410-1build1.
This file is owned by root:root, with mode 0o644.
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Add veiling glare caused by bright sources to an image.
Input is direction and illuminances of sources as may
be determined with the Radiance program, findglare(1).
N : Number of glaring sources
SDx(i) : x component of normalized direction to source i
SDy(i) : y component of same
SDz(i) : z component of same
I(i) : illuminance (lux) due to i in source's direction
(multiply the luminance by the solid angle)
An automated way to get this is to send the output of findglare
into tabfunc, i.e.:
findglare [options] | sed -e '1,/^BEGIN glare source$/d' \
-e '/^END glare source$/,$d' \
| rcalc -e '$1=recno;$2=$1;$3=$2;$4=$3;$5=$4*$5' \
| tabfunc SDx SDy SDz I > glrsrc.cal
Then, simply define N with "N:I(0)" either with a -e option to
pcomb or as an additional line in glrsrc.cal, i.e.:
pcomb -f glrsrc.cal -e 'N:I(0)' -f veil.cal orig.pic > veil.pic
}
bound(a,x,b) : if(a-x, a, if(x-b, b, x));
Acos(x) : acos(bound(-1,x,1));
{ mul(t) : if(.5*PI/180-t, 9.2/.5^2, 9.2/(180/PI)^2/(t*t)); }
mul(t) : if(1.58724464*PI/180-t, 9.2/((if(t-.00291,t,.00291)*(180/PI))^3.44),
9.2/((180/PI*t)*(1.5+180/PI*t)));
Dx1 = Dx(1); Dy1 = Dy(1); Dz1 = Dz(1); { minor optimization }
angle(i) = Acos(SDx(i)*Dx1+SDy(i)*Dy1+SDz(i)*Dz1);
sum(i) = if(i-.5, mul(angle(i))*I(i)+sum(i-1), 0);
veil = le(1)/WE * sum(N);
ro = ri(1) + veil;
go = gi(1) + veil;
bo = bi(1) + veil;
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