Quantifying spatial, temporal, angular and spectral structure of effective daylight in perceptually meaningful ways

TL;DR

This paper introduces a method to quantify the complex structure of daylight across multiple dimensions, translating it into perceptually meaningful information to better understand lighting effects on scenes and objects.

Contribution

The authors develop a 7-dimensional light field measurement technique that captures and analyzes the spectral, spatial, temporal, and angular variations of daylight in real-world conditions.

Findings

Captured daylight variations on sunny and cloudy days

Quantified diffuse and directed light components

Analyzed chromatic gradients and lighting effects

Abstract

We present a method to capture the 7-dimensional light field structure, and translate it into perceptually-relevant information. Our spectral cubic illumination method quantifies objective correlates of perceptually relevant diffuse and directed light components, including their variations over time, space, in color and direction, and the environment's response to sky and sunlight. We applied it 'in the wild', capturing how light on a sunny day differs between light and shadow, and how light varies over sunny and cloudy days. We discuss the added value of our method for capturing nuanced lighting effects on scene and object appearance, such as chromatic gradients.