Caution
All parameters are strictly positive.

For an annular source, the major diameter is strictly larger than the minor diameter.
The width of a rectangular source is along the X axis while its height is along the Y axis.
The length of a cylindrical source is along the Y axis.
For a grey body, the emissivity is between "0" and "1". If the emissivity is "1", the grey body is nothing else than a black body.

The radiometry calculation(s) can not be processed if the source is at infinity, which is the case when the object surface is at infinity.

Note that sources with a circular or rectangular shape are emitting on one side only.