WAHRSIS: A Low-cost, High-resolution Whole Sky Imager With Near-Infrared Capabilities
This provides a more accessible tool for cloud imaging applications, though it is incremental as it builds on existing whole sky imager concepts with modifications for cost and spectral range.
The authors tackled the problem of high cost and limited flexibility in commercial whole sky imagers by building a low-cost, high-resolution device called WAHRSIS that captures the entire hemisphere in a single picture across visible and near-infrared ranges.
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.