Shading factor

The shading factor is the ratio of the shaded area to the whole sensitive area. The shading factor is depending on the sun position. It is applied to the beam component.

The shading factor may also be used for the elaboration of the diffuse shading factor, which is an integral of the shading factor over all directions of the sky "seen" by the plane. In this case this is related to a light ray coming from any direction of the sky.