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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
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> 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.
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scott <sco### [at] scott com> 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.
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> 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.
Try the example below:
//--
#version 3.7
global_settings {assumed_gamma 1}
#default{ finish{ ambient 0.0 diffuse 1.0 }}
camera
{
orthographic
location z
look_at 0
right x*image_width/image_height
}
light_source{ <0,0,10> color rgb 1 }
box { -1/2 1/2 pigment{ color rgb 0.5 } }
//--
What pixel value do you get in the output image? Is it what you expect?
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