Shadow Identification in High Resolution Satellite Images in the Presence of Water Regions

Abstract

Shadow is a main obstacle in features extraction from high resolution satellite images. Water areas provide low reflectance; therefore, they are commonly classified as shadow. In traditional shadow identification procedures, shadow is identified from image histogram in which, water and shadow pixels are mixed. In this study, a new image index is presented. The index histogram separates non-shadow, shadow, and water pixels using a proposed threshold method. The developed index is then integrated into a complete approach for shadow identification. Five study areas including water, shadow on water, and shallow water regions are tested using the developed approach. Afterward, an accuracy assessment is made to demonstrate the approach efficiency. The experimental results show that the proposed approach achieved overall accuracy about ninety-three percent. The rate of detecting shadow on water is about seventy-four percent. On the other hand, shallow water is still misclassified as shadow.