Laser & Optoelectronics Progress, Volume. 58, Issue 4, 0400005(2021)

Survey of Ship Detection in SAR Images Based on Deep Learning

Xiaohan Hou*, Guodong Jin*, and Lining Tan
Author Affiliations
  • College of Nuclear Engineering, Rocket Army Engineering University, Xi’an, Shaanxi 710025, China
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    Figures & Tables(12)
    Flowchart of two-stage target detection algorithm
    Flowchart of single stage target detection algorithm
    Processing method of dataset expansion
    GaN processing process
    Framework of FPN
    Structure of hyperdense connection network
    Framework of CBAM
    Framework for context fusion algorithm
    Different target borders. (a) Target minimum outbound vertical border; (b) target minimum outbound rectangular border
    • Table 1. Existing SAR ship datasets

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      Table 1. Existing SAR ship datasets

      DatasetOpen SAR shipSSDDSAR-ship-datasetAIR-SARship-1.0
      Data informationThere are 11346 slices, including ten types of shipsThere are 1160 slices, including 2456 shipsThere are 43819 slices, including 59535 shipsThere are 31 scenes in Gaofen No. 3 SAR image
      Advantage1st ship target dataset to provide benchmark data for researchers in this fieldThe dataset contains SAR images with different resolution, polarization, sea condition, large sea area and landing conditionsThere has been a large-scale increase in the amount of data and the types of shipsIncluding ports, islands and reefs, different levels of sea conditions, the background covers variety of scenes, such as inshore and offshore
      ShortcomingThe number of samples among categories is not balanced, so it is difficult to train a better classification modelThe amount of data is still lackingMost of the datasets are offshore background, the nearshore background is less, and the background is relatively simpleThe types of vessels are still civilian ships
    • Table 2. Comparison of traditional data augmentation methods

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      Table 2. Comparison of traditional data augmentation methods

      MethodOperation methodAdvantageShortcoming
      Geometric transformationTranslationG'(i',j')=G(i+x,j+y)Enrich the position and scale of objects in the imageThe effect is not ideal in location-sensitive tasks
      RotationW'=Wcos θ+Qsin θQ'=-Wsin θ+Qcos θ
      CuttingRandom image clipping using a certain overlap ratio
      After cropping, the output needs to be scaled to a fixed size, which may cause image distortion
      ZoomRandomly select the expansion scale, place the original image in the lower right corner of the expansion image, and fill other blank areas with channel mean
      Optical transformationHueRandomly add a real number to each point in the image with a probability of 0.5Add images under different lights and scenesIn the case that the edge of the SAR image itself is not clear, it may cause the model to be difficult to converge
      Saturation degreeRandomly multiply each point in the image by a real number in the HSV gamut space
      Increase noiseGaussian/salt-and- pepper noiseG'(i',j')=G(i,j)+NG'(i',j')=G(i,j)·NGenerate robustness to natural disturbances and improve the generalization ability of the modelExcessive noise affects the output of the model
      Data source expansionChange the backgroundCombine detected objects with other background imagesIncrease the richness of the datasetThe morphological characteristics of the target itself have not been changed
    • Table 3. Comparison of algorithms in SAR ship target detection

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      Table 3. Comparison of algorithms in SAR ship target detection

      CategoryMethodAdvantageShortcoming
      Target feature extractionCharacteristic pyramidThe problem of multi-scale detection is improvedThe lower sampling rate is large, which makes the edge of the object difficult to predict, increases the difficulty of returning to the boundary, and multiple up-sampling operations increase the difficulty of detection
      Super dense connectionThe problem of gradient disappearance has been solved to some extent;a large number of features are reused and the number of channels of the feature graph is smallMultiple data replication is required, and certain video memory optimization techniques are needed
      CBAMImprove the accuracy of detectionThe speed has an impact
      Context fusionIntegrate background information, model the relationship between objects, and improve the understanding of the sceneIntroduce non-target information
      Target border designDirection designFit the multi-angle characteristics of warshipAdditional parameters need to be redesigned
      Scale designThe anchor frame is more in line with the characteristics of the dataset itselfThe more the number of anchor involved in the clustering process, the higher the accuracy, but at the same time, it will increase the amount of computation
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    Xiaohan Hou, Guodong Jin, Lining Tan. Survey of Ship Detection in SAR Images Based on Deep Learning[J]. Laser & Optoelectronics Progress, 2021, 58(4): 0400005

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    Paper Information

    Category: Reviews

    Received: Jul. 8, 2020

    Accepted: Aug. 13, 2020

    Published Online: Feb. 24, 2021

    The Author Email: Hou Xiaohan (jinguodong_army@163.com), Jin Guodong (jinguodong_army@163.com)

    DOI:10.3788/LOP202158.0400005

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