Edge Detection In SAR Images Research Articles

Training CNNs on speckled optical dataset for edge detection in SAR images

Edge detection in SAR images is a difficult task due to the strong multiplicative noise. Many researches have been dedicated to edge detection in SAR images but very few try to address the most challenging 1-look situations. Motivated by the success of CNNs for the analysis of natural images, we develop a CNN edge detector for 1-look SAR images. We propose to simulate a SAR dataset using the optical dataset BSDS500 to avoid the tedious job of edge labeling, and we propose a framework, a hand-crafted layer followed by learnable layers, to enable the model trained on simulated SAR images to work in real SAR images. The hypothesis behind these two propositions is that both optical and SAR images can be divided into piecewise constant areas and edges are boundaries between two homogeneous areas. The hand-crafted layer, which is defined by a ratio based gradient computation method, helps to tackle the gap between training and testing images, because the gradient distribution will not be influenced by the mean intensity values of homogeneous areas. The gradient computation step is done by Gradient by Ratio (GR) and the learnable layers are identical to those in HED. The proposed edge detector, GRHED, outperforms concurrent approaches in all our simulations especially in two 1-look real SAR images.

Edge Detection Algorithm of a Symmetric Difference Kernel SAR Image Based on the GAN Network Model

The symmetrical difference kernel SAR image edge detection algorithm based on the Canny operator can usually achieve effective edge detection of a single view image. When detecting a multi-view SAR image edge, it has the disadvantage of a low detection accuracy. An edge detection algorithm for a symmetric difference nuclear SAR image based on the GAN network model is proposed. Multi-view data of a symmetric difference nuclear SAR image are generated by the GAN network model. According to the results of multi-view data generation, an edge detection model for an arbitrary direction symmetric difference nuclear SAR image is constructed. A non-edge is eliminated by edge post-processing. The Hough transform is used to calculate the edge direction to realize the accurate detection of the edge of the SAR image. The experimental results show that the average classification accuracy of the proposed algorithm is 93.8%, 96.85% of the detection edges coincide with the correct edges, and 97.08% of the detection edges fall into the buffer of three pixel widths, whichshows that the proposed algorithm has a high accuracy of edge detection for kernel SAR images.

Optimized fuzzy cellular automata for synthetic aperture radar image edge detection

The development of coastline detection has been the subject of several reports. An optimized fuzzy cellular automata (FCA) algorithm for SAR image edge detection, which combines newly defined cellular automata (CAs) and fuzzy rules, is proposed. An extended Moore neighborhood is used for cellular automaton. Twelve custom masks were defined to study the edge angles of the radius two neighborhood of the main pixel. Comparing these edge angles with the radius, one neighborhood of the main pixel is useful when deciding whether or not a pixel is an edge pixel. The model was tested on two sets of images. The first dataset contained optical and simulated SAR images and the second contained an Envisat ASAR image and a ScanSAR image. A 3 × 3 Lee filter (as a preprocessing phase) was applied to each subimage containing coastlines, and the subimages were then processed using an FCA edge detector. The results were compared with those from a Sobel edge detector, Roberts edge detector, wavelet transform edge detector, and classic CA model. The results showed that the proposed method is more appropriate for edge detection of SAR images when compared with classic methods. The proposed method and wavelet transform edge detector showed good continuity, but the proposed method dealt better with speckle noise effects.

Edge detection in SAR images based on ROEWA and Hough transform

Edge detection in SAR images based on ROEWA and Hough transform

A New Method of SAR Airdrome Image Edge Detection Based on Image Character

SAR image edge detection is one of the basic contents for SAR image processing and analysis, one of SAR airdrome image edge detection methods was advanced in the paper based on the basic character of SAR airdrome image through imaging theory and target statistical trait, SAR image pretreatment was realized by synchronously using median filter, image division and mathematics morphologic, at last SAR image was edge detected using Canny arithmetic operators.

Bayesian off-line detection of multiple change-points corrupted by multiplicative noise: application to SAR image edge detection

This paper addresses the problem of Bayesian off-line change-point detection in synthetic aperture radar images. The minimum mean square error and maximum a posteriori estimators of the changepoint positions are studied. Both estimators cannot be implemented because of optimization or integration problems. A practical implementation using Markov chain Monte Carlo methods is proposed. This implementation requires a priori knowledge of the so-called hyperparameters. A hyperparameter estimation procedure is proposed that alleviates the requirement of knowing the values of the hyperparameters. Simulation results on synthetic signals and synthetic aperture radar images are presented.

A multi-scale morphological approach to SAR image edge detection

This paper introduces a multi-scale morphological edge detection algorithm to extract SAR image edge which suffers seriously from noise. Combining the basic theme of morphology with that of multi-scale analysis, the algorithm presents the outstanding characteristics of accuracy and robustness. Comparative Experiments reveal its fine performance.