  Cloud imaging using ground-based whole sky imagers is essential for a
fine-grained understanding of the effects of cloud formations, which can be
useful in many applications. Some such imagers are available commercially, but
their cost is relatively high, and their flexibility is limited. Therefore, we
built a new daytime Whole Sky Imager (WSI) called Wide Angle High-Resolution
Sky Imaging System. The strengths of our new design are its simplicity, low
manufacturing cost and high resolution. Our imager captures the entire
hemisphere in a single high-resolution picture via a digital camera using a
fish-eye lens. The camera was modified to capture light across the visible as
well as the near-infrared spectral ranges. This paper describes the design of
the device as well as the geometric and radiometric calibration of the imaging
system.
