Hyperspectral characterization of natural lighting environments.

Lights are primary drivers of some crucial biological functions including vision and regulation of circadian rhythm. To understand the light exposure pattern that we experience in a daily life, many past studies measured the spectral composition of natural daylight and artificial lighting. The aim of this book chapter is to introduce a novel method to characterize directional spectral variation in natural lighting environments. An omnidirectional hyperspectral illumination map stores the spectra of lights coming from every direction toward a single point in a scene. Such illumination maps allow us to simulate a spatial light exposure pattern that reaches our eyes, providing useful resources to research areas such as chronobiology, vision science and any other fields which benefit from knowledge about the spectral nature of visual lighting environments.