CAS <sup### [at] cstnetcn> wrote:
> I have known the value of solar irradiance in 817nm band is 1.08279
> W/(m2*nm).How can I define it?  "light_source {<sun_x,sun_y,sun_z> color rgb
> 1.08279 } "I set statement as above in pov,but I doublt it is wrong,because
> 1.08279 is a solar irradiance,color rgb is color ，but I donnot know how
> to convert them or how to define solar irradiance.beg a hot to help me !thank
> you!

Note that for the most part POV-Ray uses a quite simplistic Phong
lighting model with RGB values. It does not model light at different
wavelengths, nor is it able to process colors in any more complicated
ways than manipulating RGB values, nor are most of its lighting
calculations any more complex than the simple Phong lighting model.

(Note that "Phong lighting model", or "Phong reflection model", should
not be confused with "phong highlights". The lighting model is an
illumination model that simply adds three components to the color of
a surface: ambient (a constant), diffuse (a lighting component that's
independent of the viewing angle) and specular (a lighting component
that's dependent on the viewing angle).)

Far from me to disparage POV-Ray, but to be completely honest, the
Phong lighting model is quite poor and simplistic. (It's *major*
advantage is that it's very fast and can produce, when properly used,
acceptable results.)

If you want to convert a unit of irradiance into RGB, you'll have to
figure out the conversion formula. This is probably not a trivial task,
nor is it probably very productive because of the limitations of the
lighting model described above.

(There are many problems in getting an "accurate" conversion from some
standard irradiance unit to RGB. One of them is that the relation between
irradiance and the apparent brightness of what ends up on your monitor
screen is subject to rather complex gamma curve functions, which are not
only dependent on the gamma used by POV-Ray and the image file, but also
the gamma correction performed by your display hardware and the screen.)

-- 
                                                          - Warp

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