All-sky, video-based luminance mapper for daylighting research

A video-based system has been developed at the Solar Energy Research Institute for acquisition and luminance analysis of all-sky and interior-surface images. One of the unique features of the system is use of an orthographic-projection fisheye lens and transfer lens combination to produce an image of the entire sky dome on the camera's vidicon target. Video data for each image is digitized in real time to produce a field of data which is analyzed to produce meaningful measurements. The camera system is described and examples of all-sky luminance mapping as well as application to interior surface mapping of daylighting models are presented.