Advanced Data Processing and Research Institute, Secunderabad 500009, India.
U.R. Rao Satellite Centre, Bengaluru 560017, India.
Sensors (Basel). 2021 Apr 28;21(9):3062. doi: 10.3390/s21093062.
In recent years there has been an increased interest in ocean surveillance. The activity includes control and monitoring of illegal fisheries, manmade ocean pollution and illegal sea traffic surveillance, etc. The key problem is how to identify ships and ship-like objects accurately and in a timely manner. In this context, currently, many solutions have been proposed based on high resolution optical and radar remote sensing systems. Most often, these systems suffer from two major limitations viz., limited swath, thereby requiring multiple satellites to cover the region of interest and huge volumes of data being transmitted to ground, even though effective per-pixel information content is minimal. Another limitation is that the existing systems are either simulated on ground or built using the non-space qualified/Commercial Of-The-Shelf (COTS) components. This paper proposes an efficient on-board ship detection system/package connected with medium resolution wide swath optical camera. The methodology adopted has three major components, viz., onboard data processing for improving the radiometric fidelity, followed by a ship detection using modified Constant False Alarm Rate algorithm (CFAR) and a false alarm suppression module to mask false identifications. Finally, the package outputs only the locations of the ships, which is transmitted to the ground. The proposed system reduces the effective volume of data to be transmitted and processed on ground and also significantly cuts down the turnaround time for achieving the end objective. The system is built on radiation hardened Field Programmable Gate Array (FPGA) devices to meet the various engineering constraints such as real-time performance, limited onboard power, radiation hardness, handling of multiple custom interfaces etc. The system is tested with one of the medium resolution Multispectral Visual and Near Infra-Red (MX-VNIR) sensor having a spatial resolution of around 50 m and swath of around 500 Kms, which would be flown with one of the upcoming satellites. The systems performance is also verified on ground with Indian Remote Sensing (IRS) Satellite's Resourcesat's Advanced Wide Field Sensor (AWiFS) data and the results are found to be quite encouraging as well as meeting the mission objectives.
近年来，人们对海洋监测越来越感兴趣。该活动包括控制和监测非法渔业、人为海洋污染和非法海上交通监测等。关键问题是如何及时准确地识别船只和类似船只的物体。在这种情况下，目前已经提出了许多基于高分辨率光学和雷达遥感系统的解决方案。这些系统通常存在两个主要局限性，即有限的扫描宽度，因此需要多个卫星来覆盖感兴趣的区域，并且需要传输大量数据到地面，尽管有效像素信息含量很小。另一个限制是现有的系统要么在地面上模拟，要么使用非空间合格/商业现货 (COTS) 组件构建。本文提出了一种与中分辨率宽扫描光学相机连接的高效机载船舶检测系统/套件。所采用的方法有三个主要组成部分，即用于提高辐射保真度的机载数据处理，然后使用改进的恒虚警率算法 (CFAR) 进行船舶检测，以及虚假警报抑制模块来屏蔽虚假识别。最后，该软件包仅输出船舶的位置，并将其传输到地面。该系统减少了要传输和在地面处理的有效数据量，并大大缩短了实现最终目标的周转时间。该系统构建在辐射硬化现场可编程门阵列 (FPGA) 设备上，以满足各种工程约束，如实时性能、有限的板载功率、辐射硬度、处理多个自定义接口等。该系统使用具有约 50 m 空间分辨率和约 500 Kms 扫描宽度的其中一个中分辨率多光谱可见和近红外 (MX-VNIR) 传感器之一进行了测试，该传感器将与即将推出的其中一颗卫星一起飞行。该系统的性能也在地面上通过印度遥感 (IRS) 卫星的资源卫星先进宽视场传感器 (AWiFS) 数据进行了验证，结果令人鼓舞，并且满足了任务目标。
