scott <sco### [at] scottcom> wrote:
> > light_source {<sun_x,sun_y,sun_z>
> >               SpectralEmission(E_D80)
> >               }
> > My solar irradiance in 730nm is 1.33015.I should use E_D50 or E_D65 or
> > E_D93.Should I choose which one is my need ?Help!
> > http://en.wikipedia.org/wiki/Standard_illuminant#Illuminant_series_D
>
> 1.33015 @ 730 nm tells you the intensity of the light at a single
> wavelength (very deep red). It tells you nothing about the overall
> brightness of the light, or what the colour of that light is.
>
> The "colour" of the light is determined by the relative intensity at all
> the different wavelengths (the shape of the spectrum), the brightness by
> a combination of the absolute intensity at every visible wavelength.
>
> D50, D65 or D93 are standard distributions of wavelength intensities
> meant to represent different types of daylight, they don't say anything
> about "brightness".
>
> You either need to go back to where you got the 1.33015 figure from and
> get the rest of the data for other wavelengths, or just pick one of the
> standard illuminants to use, D65 is quite commonly used.
>
> By the way, the spectra for D65 etc are probably far more accurate in
> the middle of the visible spectrum (around 550 nm) that right at one
> edge (730 nm), so I wouldn't scale based on your value at 730 nm. If
> possible get the irradiance nearer 550 nm.

The 1.33015 figure is got from Solar_irradiance_Thuillier_2002,whcih measured by
instrument.It has the solar irradiance from 199nm to 2397nm.My test is single
wavelength first,then many wavelengths.My lightsource I used is a single
wavelength and the reflectivity of object is also a single wavelength . My major
is remote sensing.What I want to do is simulting  radiance .With the help of
pov,I have got luminance when I set openexr output.I have converted irradiance
to illuminance ,the illuminance in 730nm is 0.355*1.33015=0.47220325.I set
"SpectralEmission(0.47220325)".The result is luminance.Maybe I was wrong
,because the luminance pov got is  much larger than my real lumiance.I am
confusing.

Post a reply to this message