Regarding evalglare output

Hi All,

I need some help to understand the evalglare output.

I am getting the below values for 21-Feb 16:21 London time and location. I am using 100% Mirror in this case. I understand the formula/calculation for the Eglare_cie and the Lveil_cie. I am trying to understand how the L_s and Omega_s is calculated.

Based on few re-runs I think omega_s is no of pixels * solid angle per pixel?

Is L_s based on the Solar radiance for the time which I work out is 1646033 (0.142 altitude). The scalar radiation for mirror 100% is 294640024. How is 22245260.9 calculated from the scalar radiation?

No pixels L_s Omega_s Eglare_cie Lveil_cie teta
40 22245260.9 0.00000318 70.668517 142.535244 2.226649

Many thanks in advance

Hi @JivaBagale,

I think you may be overcomplicating things. Evalglare has no awareness of the time or solar irradiance, it processes the image knowing only the camera parameters.

Omega_s is the solid angle of the glare source. If all the pixels have equal solid angle, then your formula is correct, but there is no requirement that the pixels all have the same solid angle. It is just the sum of solid angles of the pixels that are part of the glare source.

L_s is the mean luminance of the glare source. It is the average of the luminances of the pixels that make up the glare source, weighted by the solid angle of each pixel. The glare source representing your sun no doubt includes pixels around the sun and its reflection, so it is not the same as the luminance of the sun itself.

Hi Nathaniel,

Thank you for your reply. I understand the output better now.

I managed to run a test where the surface reflects from the full sun. I get a close match between the evalglare output and mathematical calculation based on the full sun solid angle.