DESIGN OF LOW-COST, COMPACT AND WEATHER-PROOF WHOLE SKY IMAGERS FOR HIGH-DYNAMIC-RANGE CAPTURES

Ground-based whole sky imagers are popular for monitoring cloud formations, which is necessary for various applications. We present two new Wide Angle High-Resolution Sky Imag-ing System (WAHRSIS) models, which were designed espe-cially to withstand the hot and humid climate of Singapore. The first uses a fully sealed casing, whose interior tempera-ture is regulated using a Peltier cooler. The second features a double roof design with ventilation grids on the sides, allow-ing the outside air to flow through the device. Measurements of temperature inside these two devices show their ability to operate in Singapore weather conditions. Unlike our original WAHRSIS model, neither uses a mechanical sun blocker to prevent the direct sunlight from reaching the camera; instead they rely on high-dynamic-range imaging (HDRI) techniques to reduce the glare from the sun. Index Terms — WAHRSIS, ground-based sky camera, clouds, HDR imaging 1