A novel lighting control system integrating high dynamic range imaging and daLI

Conventional photosensor-based lighting control systems rely on an integrated photosensor signal that senses the overall illuminance within a space and is calibrated to address performance at a specific critical task point. All surfaces within the field of view (FOV) of the photosensor influence this signal. This paper presents a new method of lighting control that applies an inexpensive image sensor as the light sensing device in conjunction with a computer graphics technique known as High Dynamic Range imaging. A wide range of lighting levels can be evaluated using this technique, and a single sensor is capable of estimating the illuminance levels simultaneously at multiple locations on the work plane. This paper describes a calibration procedure to derive space illuminance information from the images during system operation. It also provides an algorithm to control individual luminaires to achieve different target illuminances at different points on the work plane. The solution takes full advantage of the powerful features of digital technologies, including both digital imaging and Digital Addressable Lighting Interface (DALI) ballasts. This novel solution, described as CamSensor in this paper, is a proof-of-concept for the application of High Dynamic Range imaging in the field of lighting control.