Radial Illuminance
This page describes how Radial Illuminance is calculated.
On the following example, the source is simulated by a local point source.
The sensitivity of the pixel does not depend on where the rays are coming from.
The calculation is based on the standard EN-13201, which gives mathematical formulas equivalent to different types of illuminance. Compared to the EN-13201 standard, several parameters are simplified.
The integration direction is the incident flux. This direction is on the vertical plan at right-angle to the surface. Then, the angle of incident ε is equal to 0° and cos ε = 1.
The illuminance formula is _Sensor_Irradiance_Radial_Illuminance_01.png)
_Sensor_Irradiance_Radial_Illuminance_01.png)
_Sensor_Irradiance_Radial_Illuminance_02.png)
is derived from _Sensor_Irradiance_Radial_Illuminance_03.png)
At this step, the integration directions are distinct in radial, plane.
_Sensor_Irradiance_Radial_Illuminance_04.png)
insert in Formula (dA is a spherical surface)
_Sensor_Irradiance_Radial_Illuminance_02.png)
dA and dS are surfaces.