The Effects of the Physical Characteristics of Light Probes on Image Light Perception

Abstract

The physical light field becomes apparent when it interacts with objects within a space. Human observers are able to primarily infer three light properties relevant in lighting design (1) Overall diffuse light, (2) Directed light and (3) Brilliance. Previous studies mainly used Lambertian light probes to gauge light in space by taking cues from the probes’ lighting characteristics. However, Lambertian probes fail to capture Direction and Brilliance, which allows for glossiness and atmosphere perception. We tested whether differences in material, shape and surface structure of light probes influenced the ability of observers to gather information and interpret three light properties in natural scenes. Three different light probes were used: A Lambertian sphere, a black shiny sphere and a golf ball. Participants were shown black and white images of one of the probes photographed in a scene. Some images had the probe originally photographed in the scene, but in other images the probe was swapped for that of a different scene, creating different combinations of probe and scene. Participants had to determine whether the probe “fitted” the scene. This project aims to consolidate light probes as a design tool and help lighting professionals correctly represent a space’s illumination using the light probe that best captures the light properties at play in a scene. Overall, black shiny probes have proven to be better at helping determine light than Lambertian spheres. Our hypotheses that one probe type is better than others in helping infer certain light properties in scenes with similar features cannot be proven, but significant results at the image level suggest a conditional relationship of this matter might exist