Based on the light distribution curve and the size of the lamps measured in the laboratory, the glare index under typical ideal lighting environment (such as lighting arrangement, room reflectance, etc.) is simulated by software. However, there is a big gap between theory and practice, and there is a big risk in this method.
Luminance measurement based on point-of-sight:
The traditional point-of-sight brightness meter is used to measure the brightness of the dizzy light source one by one at the observation position, and the ambient brightness is measured and converted by the illuminometer. The size and relative angle of the dizzy light source are obtained by length measurement, which wastes the time and the labor. More importantly, when the shape of the light source is irregular or the luminous surface is not uniform, the measurement accuracy will be greatly affected.
Measurement based on imaging brightness:
At present, it is considered as a simple and accurate method in the world, and CIE has also established TC 2-86, aiming to evaluate the glare index by using the brightness distribution measured by the imaging luminance meter.
Although all the elements of glare index evaluation are obtained by imaging brightness measurement, there are also some requirements for the performance of imaging luminance meter, such as V (lambda) spectral matching, linearity, image distortion and so on. Common cameras are far from meeting the above requirements.