Abstract
The purpose of this study is to identify the turning point where contrast glare shifts to grand total glare, namely saturation glare. The existing glare indices for large glare sources are examined and classified depending their evaluation of the contrast effect and grand total effect. Two series of experiment are conducted; in the first experiment pre-adaptation level is constant, and in the second the pre-adaptation level equals to the background luminance. The result of the first experiment shows that the glare sensation increases with background luminance the case with a higher background luminance. In the second experiment shows that elapsed time cannot reduce saturation glare while it can reduce contrast glare. PGSV can predict glare sensation for contrast glare. However, for saturation glare, background should be considered as a part of glare source and the calculation method of PGSV should be changed.
