A Novel Data-Driven Scheme for the Ship Wake Identification on the 2-D Dynamic Sea Surface

Abstract

Because the ship wake spreads into an area much larger than that of the ship hull in the sea surface, it has been widely used in the ship detection. However, due to the complex sea wave motion and the high sea state, the ship wake detection is still a challenging task. In this paper, we propose a novel data-driven method based on dynamic mode decomposition (DMD) to detect, reconstruct, and locate the Kelvin wake on the two-dimensional dynamic sea surface. Through the proposed method, the sea's dynamic characteristics including the oscillation frequency and decay/growth rate of ship wakes and the time-varying sea surface can be obtained. Meanwhile, the spatial features of ship wakes can be derived by dynamic modes as well. The proposed method can distinguish the dynamic characteristics between the Kelvin wake and sea background. Then the corresponding modes of the Kelvin wake can be successfully identified. The proposed method is demonstrated by analyzing a 2D sea surface where the Kelvin ship wake is superposed. It is found that our new approach provides an effective and accurate ship detection, even in the case of high sea states. Meanwhile, the extracted mode of the wake shows the ship position clearly with very high resolution.

Modeling and SAR imaging of the sea surface: A review of the state-of-the-art with simulations

“…According to the results in Table II, for all spectra except the S F L spectrum, the better visualization of wakes on most measures generally follows a decrease of the significant wave height H s , which is consistent with previous simulation studies [6], [71], [140] or real images analysis [7], [61], [131]. As expected, the best performance is shown by S J model (the fetch size is 25 km), where the H s is around half compared to most of the presented spectra, so the amplitude of the wake is not washed out by the surrounding waves.…”

Modeling and SAR Imaging of the Sea Surface: a Review of the State-of-the-Art with Simulations

“…According to the results in Table II, for all spectra except the S F L spectrum, the better visualization of wakes on most measures generally follows a decrease of the significant wave height H s , which is consistent with previous simulation studies [6], [71], [136] or real images analysis [7], [61], [128]. The best performance is shown by S J model (the fetch size is 25 km), where the H s is around half compared to most of the presented spectra, so the amplitude of the wake is not washed out by the surrounding waves.…”

Reconstruction of three-dimensional ship wake by Tiangong-2 interferometric imaging radar altimeter

“…The streak on water surface behind a moving ship is called wake, and it has been widely used in ship detection because the wake spreads over an area much larger than that of the ship itself. The ship position can be obtained according to wake, and other information can be retrieved according to the wake feature [1], which are then utilized to monitor and recognize different ships.…”

“…It is well known that the wave pattern generated by a moving ship is formed by two dominant features: the turbulent wake and a V-shaped pattern trailing the ship, and Kelvin wake is the most common one [2]. Classical ship wave theory shows that the most obvious components in Kelvin wake are the Kelvin arms, which were formed by divergent ship waves with a wedge of half-angle arcsin(1/3) (about 19.5°), and the Kelvin angle has nothing to do with the ship speed [1], [3]. So, the largest surface perturbation on the Kelvin wake is located on Kelvin's arms, and the angle between the two Kelvin arms is generally about 39° [3].…”