Hi Parisa,
in fact these are weighting functions derived from v(lamda). So you should use them only when all your quantities are in photometric units. Irradiance "usually" implies the solar spectrum, but in RADIANCE this is used also only considering the visible spectrum (and then using the weighting). I'm not sure if a color weighting makes sense when talking about radiometric quantities using the solar spectrum. Usually I calculate everything in "grey" (r=g=b) when using the radiometric quantities, so this problem doesn't occur. Be aware, that you usually calculate everything in photometric quantities in RADIANCE, so if you want to calculate the solar spectral behavior you have to take care of using the related values(solar transmittance for glazing, solar reflectance of surfaces and generate sky and sun with radiometric quantities). As far as I know only if you use gendaylit with the -O 1 option, then sky and sun are automatically in radiometric quantities (which means your results are in W/m*m solar spectrum).
Jan
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Am 6/22/15 um 5:50 PM schrieb parisa khademagha:
Dear all,
I have two questions regarding the weighting factors (0.265, 0.670, 0.065) that are used in the formula ( I = 0.265 I_R + 0.670 I_G + 0.065 I_B ) with which one can convert the spectral irradiance triad to irradiance. My first question is: where these weighting factor come from? Do they incorporate the spectral sensitivity of the human eye (so called V(λ)) in the irradiance calculation? My second question is: should the summation of these weighting factors be always equal to 1.
Thank you in advance,
Parisa
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