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> Can POV get a render picture of physical meaning such as radiance ?Or POV only
> get a picture having nothing physical meaning in it ?I have got a picture by
> pov,but I donot know what physical meaning in it?
>
>
POV-Ray is not intended to generate images that have physical "meaning",
but ones that are physicaly acurate.
If you want some "meaning" like radiance, you should use *.HDR or *.RAD
format as your output. Those are high dynamic range image format where
the RGB values are stired as floats. You absolutely need to use the
version 3.7 to have access to those formats.
If you use "normal" image format, you can get some clipping for very
dark (to zero) and bright (to one) regions.
Using the PNG format, you can have up to 16 bits per channel. This allow
for much finer granulosity in the brightness.
A possibility could be to get some "expanded" dynamic range by dividing
your illumination by some factor, like by 256 and get the equivalent of
the regular render in the lower 8 bits and the brightest areas having
non-zero values in the top 8 bits...
Alain
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Alain <kua### [at] videotron ca> wrote:
> > Can POV get a render picture of physical meaning such as radiance ?Or POV only
> > get a picture having nothing physical meaning in it ?I have got a picture by
> > pov,but I donot know what physical meaning in it?
> >
> >
>
> POV-Ray is not intended to generate images that have physical "meaning",
> but ones that are physicaly acurate.
>
> If you want some "meaning" like radiance, you should use *.HDR or *.RAD
> format as your output. Those are high dynamic range image format where
> the RGB values are stired as floats. You absolutely need to use the
> version 3.7 to have access to those formats.
>
> If you use "normal" image format, you can get some clipping for very
> dark (to zero) and bright (to one) regions.
> Using the PNG format, you can have up to 16 bits per channel. This allow
> for much finer granulosity in the brightness.
> A possibility could be to get some "expanded" dynamic range by dividing
> your illumination by some factor, like by 256 and get the equivalent of
> the regular render in the lower 8 bits and the brightest areas having
> non-zero values in the top 8 bits...
>
>
> Alain
I know the solar irradiance in 817nm is 1.08279(W/m2/nm).Then I convert
XYZ=(3.815429E-06,1.523114E-06,0.000000E+00) to linear RGB,then I set
"light_source {<sun_x,sun_y,sun_z>
color rgb <1.00229e-005,3.46021e-006,-5.65828e-007> }"; I also have defined the
output file type *.hdr. The first column is the value of each pixel of hdr image
which simulated by pov;The second column is the value of each pixel of my real
image which is reflection image.I found the value of each pixel of hdr is 10
times smaller than my reflection.I donot know why?I analyse this two
columns.They are trend is the same,only real reflection is 10 times bigger than
simulated HDR by pov.My goal is the two column is the same.Because my aim is
simulating reflection iamge.
0.021973 0.220900
0.037354 0.375800
0.037354 0.375800
0.034424 0.346500
0.027710 0.277700
0.035400 0.355800
I have checked my code.Maybe my wrong is something as below:
"sphere
{
<x1-center_x,y1-center_y,z1-center_z>,
1.55
pigment {color rgb spectral}
} "
The above code is what I defined in POV to describe objects in scene." pigment
{color rgb spectral} "I doublt this statement is wrong."spectral"is a txt which
I input real reflection value of each sphere ,the values are as folllows:
0.220900
0.375800
0.375800
0.346500
0.277700
0.355800 they are all float values.But I have defined "color rgb ".So maybe
this wrong.But I donot know how can I to define.Beg a help!
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