Edge-based detection of sky regions in images for solar exposure prediction

Abstract

A device for predicting the solar exposure at a location operates by gathering image data from that location with a known camera orientation. The image data is then processed to identify the sky regions and the solar exposure is predicted using a standard sun path model and tracing the rays from the sun through the processed images. Critical to the success of this technique is the image processing used to separate the sky from the rest of the image. This work is concerned with developing a technique which can do this for images taken under different weather conditions. The general approach to separate the sky from the rest of the image is to use the Canny edge detector and the morphology closing algorithm to find the regions in the image. The brightness and area of each region are then used to determine which regions are sky. The FloodFill algorithm is applied to identify all pixels in each sky region.