Hey,my name is miaoyu, I am a student,and I am studying pov to do my graduation
project.I have confronted some confusions,please give me a help,expecting your
replying!Greate gratitudes!

1: how does pov calculate the value of each pixel of final image? My
understanding is :using the irradiance and surface properties to calculate the
value of each pixel of final image. Using the simplistic Phong lighting model to
calculate the color of each pixel of final image.I didnot set related "phong"
statements but also get a result.my codes are given below,I beg you have a check
whether it is true.Emphasisly,my reflection is BRDF（dependent on suning
angle、viewing angle 、wavelength）.I use "specular X".Is it
right?

2: I know irradiance 1.08279W/(m2*nm).I have converted XYZ to the values of
color rgb using formula,my conversion formula is:
r=(3.2406*3.815429E-06)+(-1.5372*1.523114E-06)
g=(-0.9689*3.815429E-06)+(1.8758*3.815429E-06)
b=(0.0557*3.815429E-06)+(-0.2040*3.815429E-06)
but the value of b is negative,it must be something wrong in it.I only know the
solar irradiance is 1.08279W/(m2*nm),not know what color the light_source,so how
can I code with it? "color rgb 1.08279 "must be wrong?

3: HDR image is a image of scene,its dynamic range is generally more than 100:
l,and record each pixel which value is real scene brightness (CD/m^2).so I
regard it as radiance.is it right?

Below is my all code:
"#version 3.7;

//camera information:
camera
{
angle  7.54371
location <camera_x,camera_y,camera_z >
look_at <0,0,0>
rotate <0,-31,0>
right x
up y
}

//light information:
light_source {<sun_x,sun_y,sun_z>
            color rgb <1.00229e-005,3.46021e-006,-5.65828e-007>
             }
//scene information:
#declare geom_file_name = "pov-xyz.txt";
#declare spec_file_name = "pov-ref.txt";
#declare n=o;
#fopen   Input_geom_file geom_file_name read
#fopen   Input_spec_file spec_file_name read
#while(defined(Input_geom_file Input_spec_file))
    #read(Input_geom_file,x1,y1,z1)
    #read(Input_spec_file,ref)
        sphere
        {
        <x1-center_x,y1-center_y,z1-center_z>, //sphere location
         1.55     //sphere radius
        finish {specular ref}  //sphere specular
        }
    #declare n = n + 1;
#end

Beg a hot!
                                                                      miaoyu

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