Hi,
I try to understand how RADIANCE calculate the radiance values, but the specular value for one reflection isn't clear.
I understand, that the diffuse value is independent of view. On point P_r=(0 1 1) I got from rtrace for the red channel 0.22361, I calculated:
R_r_light=100
sphere_radius=0.5
distance=2.2360
rho_surf1=0.1
cos(63,43) = light incoming angle
R_r(0,1,1) = R_r_light * (sphere_radius)² / (distance)² * cos (63,43) * rho_surf1 = 0.223606797.
Ok, this value is fine, but what will happen if I look from (0 -1 1) to (0 1 -1) at point (0, 0, 0), I thought this, but it didn't work:
distance=3
rho_mirr=0.3
diff=0.9
spec=0.1
cos(45) = reflected light - observer angle
P_r=0.22361
R_r(0,0,0) = R_r_light * (sphere_radius)² / (distance)² * rho_mirr * diff + spec * P_r * cos(45) = 0.765811388
rtrace = 0.76517
Can somebody explain how the specular component is calculated on my test scene? I do not get it...
Here is my test scene:
######materials.rad######
void plastic mirr
0
5 .3 .2 .1 0.1 0
void plastic surf1
0
5 .1 .1 .1 0 0
void light lighty20
0
3 100 150 200
######test.rad######
mirr polygon plate1
0
12
-1 -1 0
1 -1 0
1 1 0
-1 1 0
surf1 polygon plate2
0
12
-1 1 0
-1 1 3
1 1 3
1 1 0
lighty20 sphere light_s
0
4 0 0 3 0.5