Shadow detection in colour high-resolution satellite images

Image shadow segmentation has become a major issue in satellite remote sensing because of the recent commercial availability of high-resolution images. Detecting shadows is important for successfully carrying out applications such as change detection, land monitoring, object recognition, scene reconstruction, colour correction, etc. This paper presents a simple and effective procedure to segment shadow regions on high-resolution colour satellite images. The method applies a region growing process on a specific band (namely, the c(3) component of the c(1)c(2)c(3) colour space). To gain in robustness and precision, the region expansion also imposes a restriction on the saturation and intensity values of the shadow pixels, as well as on their edge gradients. The proposed method has been successfully tested on QuickBird images acquired under different lighting conditions and covering both urban and rural areas.