Extraction of water areas based on similarity analysis using pixel-level SAR image time series

Abstract

In view of the characteristics of SAR images stack data,this paper presents a method for extraction of the water area based on similarity analysis using pixel- level SAR image time series. The basic idea is as follows:Firstly,the pixel- level SAR image time series is constructed,and the dynamic time warping( DTW) is chosen as the similarity measurement to compute the similarities between all the pixels and sampled water pixel. Then,the water pixels are extracted with the threshold value method,referring to the DTW distance of mixed pixels on borders of water for threshold value. Lastly,by replacing the backward scattering coefficients with DTW distance of each pixel,the accuracy of water identification is improved by 8- connected method. 25 wide- swath ENVISAT ASAR images collected during the period from January to December in 2008,which have 150 m spatial resolution,were utilized to extract water pixels in the study area. The result shows that the water pixels extracted by this method have high accuracy and integrity,thus proving that this method is practical in the extraction and mapping of water body distribution at the large regional scale.