Superpixel-Level CFAR Detectors for Ship Detection in SAR Imagery

Odysseas Pappas,Alin Achim,David Bull

doi:10.1109/lgrs.2018.2838263

Odysseas Pappas, Alin Achim + Show 1 more

Open Access

https://doi.org/10.1109/lgrs.2018.2838263

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Abstract

Synthetic aperture radar (SAR) is one of the most widely employed remote sensing modalities for large-scale monitoring of maritime activity. Ship detection in SAR images is a challenging task due to inherent speckle, discernible sea clutter, and the little exploitable shape information the targets present. Constant false alarm rate (CFAR) detectors, utilizing various sea clutter statistical models and thresholding schemes, are near ubiquitous in the literature. Very few of the proposed CFAR variants deviate from the classical CFAR topology; this letter proposes a modified topology, utilizing superpixels (SPs) in lieu of rectangular sliding windows to define CFAR guardbands and background. The aim is to achieve better target exclusion from the background band and reduced false detections. The performance of this modified SP-CFAR algorithm is demonstrated on TerraSAR-X and SENTINEL-1 images, achieving superior results in comparison to classical CFAR for various background distributions.

Highlights

S YNTHETIC aperture radar (SAR) has established itself in recent years as an excellent remote sensing modality for many monitoring tasks, largely due to its round-the-clock operation capabilities, independent of weather conditions and cloud coverage
This SP-level Constant false alarm rate (CFAR) (SP-CFAR) architecture can be utilized with most prior sea clutter statistical models or thresholding schemes
CFAR detectors are a type of sliding window, adaptable threshold detectors that first originated within radar target detection literature

Summary

INTRODUCTION

S YNTHETIC aperture radar (SAR) has established itself in recent years as an excellent remote sensing modality for many monitoring tasks, largely due to its round-the-clock operation capabilities, independent of weather conditions and cloud coverage. In the high resolution SAR images produced by modern, state-of-the-art platforms, the ship’s wake, the sea state (i.e., presence and size of waves), and other clutter become more discernible; this can result in a much more heterogeneous background over which ship target detection is to be performed. Our method relies on the use of SPs in lieu of guard and background bands, with the aim to achieve better target exclusion within the guardband, improved clutter homogeneity in the background band, and robustness to the presence of multiple targets This SP-level CFAR (SP-CFAR) architecture can be utilized with most prior sea clutter statistical models or thresholding schemes.

CFAR DETECTORS

SUPERPIXEL-LEVEL CFAR

RESULTS