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{ RCSid $Id: veil.cal,v 1.2 2018/11/21 18:10:45 greg Exp $ } |
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{ |
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Add veiling glare caused by bright sources to an image. |
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Input is direction and illuminances of sources as may |
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be determined with the Radiance program, findglare(1). |
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|
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N : Number of glaring sources |
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SDx(i) : x component of normalized direction to source i |
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SDy(i) : y component of same |
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SDz(i) : z component of same |
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I(i) : illuminance (lux) due to i in source's direction |
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(multiply the luminance by the solid angle) |
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|
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An automated way to get this is to send the output of findglare |
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into tabfunc, i.e.: |
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|
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findglare [options] | sed -e '1,/^BEGIN glare source$/d' \ |
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-e '/^END glare source$/,$d' \ |
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| rcalc -e '$1=recno;$2=$1;$3=$2;$4=$3;$5=$4*$5' \ |
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| tabfunc SDx SDy SDz I > glrsrc.cal |
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|
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Then, simply define N with "N:I(0)" either with a -e option to |
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pcomb or as an additional line in glrsrc.cal, i.e.: |
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|
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pcomb -f glrsrc.cal -e 'N:I(0)' -f veil.cal orig.pic > veil.pic |
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|
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WARNING: Do not use the 'N:I(0)' setting if there is only a single |
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glare source. Use 'N:1' instead, as tabfunc outputs a constant |
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value for a single input line, and the trick does not work then. |
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} |
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|
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bound(a,x,b) : if(a-x, a, if(x-b, b, x)); |
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Acos(x) : acos(bound(-1,x,1)); |
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|
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{ mul(t) : if(.5*PI/180-t, 9.2/.5^2, 9.2/(180/PI)^2/(t*t)); } |
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|
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mul(t) : if(1.58724464*PI/180-t, 9.2/((if(t-.00291,t,.00291)*(180/PI))^3.44), |
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9.2/((180/PI*t)*(1.5+180/PI*t))); |
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|
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Dx1 = Dx(1); Dy1 = Dy(1); Dz1 = Dz(1); { minor optimization } |
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|
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angle(i) = Acos(SDx(i)*Dx1+SDy(i)*Dy1+SDz(i)*Dz1); |
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|
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sum(i) = if(i-.5, mul(angle(i))*I(i)+sum(i-1), 0); |
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|
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veil = le(1)/WE * sum(N); |
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|
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ro = ri(1) + veil; |
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go = gi(1) + veil; |
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bo = bi(1) + veil; |
