Sun-Coefficient simulation of 5-phase method

radiance-general
1

Hi all,
As for the sun-coefficient simulation part of 5-phase method, the annual sky-matrix is generated as follows:

gendaymtx -m 6 -5 0.533 -of assets/NYC.wea > skyVectors/NYCd6.smx

where -m 6 means 5185 subdivisions of sky and the term -5 0.533 indicates that the sky-matrix is being generated for the Five-Phase Method. The value of 0.533 corresponds to the size of the solar disc. How to calucate this value 0.533?
So there is a question: when m is other number like 1, and the subdivisions are 145, so how about the corresponding size of solar disc? I guess the value should be larger than 0.533. And what is the relationship between the m and the size of the solar disc?
Any help or advice is appreciated!

2

The subtended solar angle is 0.533 degrees measured from Earth’s orbit, and this doesn’t (and should not) change with the -m setting. It is there to normalize the solar radiance to its true value, rather than spreading it over the solid angle of the sky patch as gendaymtx would do without the -5 option. (In fact, it normally spreads the sun over the 4 nearest patches.) The reasons behind it are specific to the handling of the solar position matrix in the 5-phase method.

3

Hi Greg,
Thanks for your reply!