Edge detection is a fundamental issue in synthetic aperture radar(SAR)image interpretation.The multiplicative noise makes edge detection in SAR image extremely difficult

and the typical edge detectors based on gradients are inefficient when applied to SAR images.So developing edge detectors especially for SAR image is of great importance.This paper investigates the problem of edge detection for SAR images comprehensively and thoroughly.It first describes the problem of edge detection for SAR images

and then discusses several well-known edge detection methods and two key points in SAR image edge detection-edge thinning and localization.To evaluate edge detector quantitatively

some performance criteria are summarized.In the end of this paper

conclusions are made and the possible future work is explained.