Change detection and analysis with radarsat-1 SAR image

In the present paper, according to data analysis, the problem of change detection has been addressed with unsupervised change detection with multi-temporal single- channel single-polarization RADARSAT-1 SAR images. Method proposed in this paper is based on four main steps: (1) Data preprocessing. SAR images are rectified and calibrated to Gauss-Kruger projection firstly. Moreover they are co-registered to ensure the condition of good accuracy of change detection. (2) Change detection. The window log-ratio approach is adopted to compare multi-temporal SAR data, because of the multiplicative speckle in the images. Then a proper window is selected to average pixels from the two SAR data in log-ratio process instead of pixel by pixel. (3) Selection of optimal threshold value. Minimum error threshold is applied to find the optimal threshold. (4) Change detection map can be obtained by segmentation of window log-ratio image. Experiments show the approach deal well with change detection in water area.