Re Re: [Radiance-general] mgfilt, degree Kelvin into spectral data

[Gregory J. Ward]

Hi Christian,

The two spectra do not have to be normalized to the same value.  In  
fact, you can multiply the cspec output by mgfilt by the lumens of  
your light source and the transmission of your filter (between 0 and  
1 at each wavelength) and get something related to the lumen output  
over the spectrum.

Man pages for MGF can be found on the website -- I assumed you had this:

	http://radsite.lbl.gov/mgf/

-Greg

> From: Christian Fusenig <christian_fusenig at gmx.de>
> Date: April 6, 2006 2:39:33 AM PDT
>
> Thanks for your answer Greg,
> ---------------------
> The normalization of the spectral power distribution is  
> unimportant,  but I believe mgfilt outputs something that sums to  
> 1.0 when  integrated with the photopic curve.  Whatever it comes  
> out to, the  actual value is normalized by the reflectance or  
> emission it's  applied to.  Since you aren't applying it to  
> anything, it doesn't  matter.
> ----------------------
> The problem is, i am applying the spectrum of this lamp to a color  
> filter spectrum.
> The spectral data of this filter is normalized to 1 or 100%. There  
> are values from 0,0000 up to 1.
> If i multiply these two spectra as shown in "Rendering with  
> Radiance" p.435, i think the data should be normalized
> to the same standard, or am i wrong?
> My output is a combined spectrum and then i convert it back to  
> CIExy values, then with xyz_rgb.cal to RGB.
> Thats why i want to know how mgfilt works and what it is capable  
> of. Is there any man page?
> Regards,
>
> Christian