سابِق|تال

Improved ROEWA edge detector for SAR Images

  • role： First author第一作者
  • Affiliation：

    State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology), Chengdu 610059, China

    Key Laboratory of Geoscience Spatial Information Technology, Ministry of Land and Resources of the P. R. China, Chengdu 610059, China

    College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China

  • Email：liuhang326@163.com
  • Introduction：刘夯(1990—　)，男，硕士研究生，研究方向为微波遥感应用、计算机视觉。E-mail：liuhang326@163.com
LIU Hang123,  
  • Affiliation：

    State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology), Chengdu 610059, China

    Key Laboratory of Geoscience Spatial Information Technology, Ministry of Land and Resources of the P. R. China, Chengdu 610059, China

    College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China

HE Zhengwei123,  
  • Affiliation：

    Key Laboratory of Geoscience Spatial Information Technology, Ministry of Land and Resources of the P. R. China, Chengdu 610059, China

    College of Tourism and Urban-Rural Planning, Chengdu University of Technology, Chengdu 610059, China

ZHAO Yinbing24,  
  • Affiliation：

    Key Laboratory of Geoscience Spatial Information Technology, Ministry of Land and Resources of the P. R. China, Chengdu 610059, China

TENG Jing2,  
  • Affiliation：

    School of Resources and Environment, University of Electronic Science and Technology of China, Chengdu 611731, China

WANG Yong5

ملخص

This paper reports on a method to improve the Ratio Of an Exponentially Weighted Averages (ROEWA) edge detector, so that the improved edge detector can accurately determine the positions and directions of edges for Synthetic Aperture Radar (SAR) images. We attempt to build an optimal edge detector for SAR images to obtain better results of edge detection. The edge strength index is redefined as an inverted, signed, and normalized minimum ROEWA (IROEWA), which is utilized to quantitatively describe the phase step of edges. A new method that accurately calculates edge direction is developed based on the edge strength map from IROEWA. We can obtain the possible values of edge directions in this manner, which continuously distributes from 0 degrees to 180 degrees. Therefore, we must improve the Non-Maximum Suppression (NMS) algorithm, so that it can process sub-pixels. Finally, the improved NMS algorithm is also added into the edge detection workflow. This improved edge detection algorithm is called IROEWA & NMS. We conducted two experiments for IROEWA & NMS: one employed nature SAR images, whereas the other adopted a simulation SAR image. Experiment results show that the IROEWA & NMS outperforms the original ROEWA with watershed thresholding. The IROEWA operator is faster than the ROEWA operator under the same conditions. We applied a Receiver Operating Characteristic (ROC) curve to evaluate the IROEWA & NMS and determined that its Area Under the Curve (AUC) is 0.97570; thus, it approximates the ideal optimal detector. The detection rate at the position of the optimal point in the ROC curve of the IROEWA & NMS is as high as 0.95232, whereas the false alarm rate is as low as 0.00214. The IROEWA & NMS exhibits suitable performance on both the detection and false alarm rates. It has significant application value in several fields, such as the segmentation and edge detection for SAR images.

مفهوم

SAR images;edge detection;ROEWA;Non-Maximum Suppression(NMS);Receiver Operating Characteristic(ROC)

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