Automatic Balloon Snake Method for Topology Adaptive Water Boundary Extraction: Using GF-1 Satellite Imagery as an Example

Abstract

Topology adaptive boundary extraction for water in satellite images using parametric snakes remains challenging in the domain of image segmentation due to the inability of topology inflexible parametric snakes (TIPS) to split and merge curves and the limited accuracy or inefficiency of topology flexible parametric snakes (TFPS). Based on the balloon snake (B-snake) method, an outstanding representative of TIPS, this paper proposed the automatic B-snake (AB-snake) method capable of automatic initialization and topology transformation to overcome the drawbacks of nonautomatic initialization and topology inflexibility of the B-snake method while ensuring both high accuracy and efficiency of TFPS. Six GF-1 wide field view satellite images covering different inner island numbers, water body sizes, boundary complexities, boundary clarities, and background complexities were used as experimental images. To test its feasibility and advantages, the extracted results of the AB-snake method were compared with those of the B-snake and the orthogonal topology adaptive snake (OT-snake) methods, a newer representative of TFPS. The results demonstrated that the AB-snake method could effectively implement automatic initialization and topology transformation, successfully meeting its design objectives. Four indices, including correctness, completeness, area overlap measure, and efficiency, were adopted to quantitatively assess the performances of the B-snake, the AB-snake, and the OT-snake methods. The results suggested that the proposed AB-snake method not only significantly outperformed the B-snake method in topology collision handling but also demonstrated great advantages over the OT-snake method in accuracy. The applicability, sensitivity, parameter selection, and limitations of the AB-snake method were also elaborated.