I am trying to understand the output of mkillum. The dat-files are written in Radiance's standard format. So I should be able to understand the header. However I am not really sure whether I am doing the right thing here. Take an example:
1.041667 0.041667 13
0.000000 6.283185 39
1.504918e+00 1.530097e+00 1.525389e+00 1.501599e+00 1.505246e+00
1.461270e+00 1.463038e+00 1.489136e+00 1.481565e+00 1.451201e+00
1.374334e+00 1.296027e+00 1.410817e+00 1.343876e+00 1.477319e+00
1.365996e+00 1.366200e+00 1.397315e+00 1.407394e+00 1.484092e+00
1.482776e+00 1.570183e+00 1.525340e+00 1.572320e+00 1.561935e+00
1.576046e+00 1.486079e+00 1.629394e+00 1.528797e+00 1.621227e+00
1) I have a two-dimensional array (line 1) of 13 rows and 39 columns (lines 2, 3), right?
2) The rows are counted down from 1 to 0 (the 0.041667 probably is some error to avoid 0), thus in steps of 1/13=-0.0769 .
3) The columns are counted up from 0 to 2*pi in steps of 6.2832/39=0.1611 .
4) This means that the columns represent the "azimuth angle" (the angle in the plane of the illum surface) from 0 to 2*pi radians, the rows are related to.... what? If it were the elevation angle (the angle to the surface normal of the mkillum surface), why is it not counted beyond 1 radians? Or what else is it?
In illum.cal which is referred to by the illum-modifier generated by mkillum, I find these comments:
For the hemispherical case, A1-A9 are the unit vectors for the
hemisphere's coordinate system:
il_alth - Altitude (1 to 0) for hemispherical coordinates
il_azih - Azimuth (0 to 2*PI) for hemisphere
It would be great if anyone could shed some light onto this...