Lighting measurement with a 360° panoramic camera: Part 2 – Applications

Abstract

This study developed a 360° field of view (FOV) lighting measurement method with the aid of the Ricoh Theta Z1 panoramic camera. As versatile lighting information from all viewing directions within 360° FOV can be retrieved from a single 360° high dynamic range image, this new method improves the lighting measurement efficiency. Potential unique applications are reported in the present paper as Part 2 of this study. Corresponding lighting information covers a 360° luminance map, a 360° coefficient of variation map of luminance (CVL), a 360° luminance contrast (C1) map or ratio (Cr1) map between any interested target located at the viewing direction and its near background, a 360° luminance contrast (C2) map or ratio (Cr2) map between the same target and the ambient environment and a 360° illuminance map and its single coefficient of variation of illuminance (CVE) value of all illuminances on the illuminance map. All lighting information is measured at the same point with 360° viewing directions to analyse the uniformity and continuity of the lighting environment. An angular distance weighted illuminance calibration is used to correct possible mismatched white balance of the front and rear camera lenses in a scenario with multiple light sources of dramatically different Correlated Colour Temperature (CCTs). All customized camera-control and data treatment programs, including MATLAB code and Python programs, are uploaded to the project GitHub site for online sharing.