Quantifying CIE alpha-opic signals in the indoor built environment

As humans spend more time in mixed-illuminant "built" environments, it is important to quantify how light in indoor spaces differs from naturalistic scenes. Previous studies have quantified light across many natural environments and shown regularities in the chromatic variation across different seasons, times of day, and weather patterns. This study measures light in a typical mixed-illuminant office space in the northern hemisphere (51.76°N, -1.27^∘<i>W</i>) and finds that it shares some regularities of chromatic variation with naturalistic scenes. In this dataset, such regularities are primarily conveyed through outdoor light entering through east- and north-facing windows and reflected by surfaces inside the office, rather than by light directly imaged through the north-facing window that was visible in the camera field-of-view. Built environments that combine natural daylight and artificial light to create mixed-illuminant spaces can share many of the statistical regularities that have been found in natural environments.