Laboratory Experiment

Scaled Model

In 2020, Center researchers built a scaled physical model of a parking lot (Figure 2) to present scenes using combinations of four average illuminances ranging from 2.5 lx to 20 lx, three correlated color temperatures (CCTs) ranging from 2850 K to 5800 K, and three illuminance uniformity ratios ranging from 2:1 to 15:1 (maximum-to-minimum). 

Figure 2. The model parking lot used in the laboratory experiment.

Participant Evaluation

Participants in the experiment viewed each scene from the same position and were asked to rate its perceived safety on a scale from -2 (very unsafe) to +2 (very safe) (Figure 3).

Figure 3. Examples from the range of spectral distribution (high vs. low CCT) and illuminance uniformity (high vs. low) scenarios that were presented to laboratory experiment participants.