Ship Classification Research Articles

Ship Classification Based On Co-Occurrence Matrix and Support Vector Machines

Ship Classification Based On Co-Occurrence Matrix and Support Vector Machines

Physics-Informed Data-Driven Approaches to State of Health Prediction of Maritime Battery Systems

Battery systems are increasingly being used for powering ocean going ships, and the number of fully electric or hybrid ships relying on battery power for propulsion and maneuvering is growing. In order to ensure the safety of such electric ships, it is of paramount importance to monitor the available energy that can be stored in the batteries, and classification societies typically require that the state of health (SOH) of the batteries can be verified by independent tests – annual capacity tests. However, this paper discusses physics-informed data-driven approaches to online diagnostics for state of health monitoring of maritime battery systems based on a combination of physical knowledge, physic-based models, insights from extensive characterization tests and operational sensor data collected from the batteries during actual operation. This represents an alternative approach to the annual capacity tests for electric ships that is found to be sufficiently robust and accurate under certain conditions. Previous attempts with purely data-driven models, including both cumulative and snapshot models, semi-supervised learning and simple models based on the state of charge did not achieve the required reliability and accuracy for them to be utilized in a ship classification perspective, as presented at previous PHM conferences. However, preliminary results from the physics-informed data-driven method presented in this paper indicate that it can be relied on for independent verification of state of health as an alternative to physical tests. It has been tested on battery cells cycled in laboratory degradation tests as well as on field returns from batteries onboard ships in service. Notwithstanding, further validation and verification of the method is recommended to further build confidence in the model predictions.

Multi-scale attention–based adaptive feature fusion network for fine-grained ship classification in remote sensing scenarios

Multi-scale attention–based adaptive feature fusion network for fine-grained ship classification in remote sensing scenarios

CPINet: Towards A Novel Cross-Polarimetric Interaction Network for Dual-Polarized SAR Ship Classification

With the rapid development of the modern world, it is imperative to achieve effective and efficient monitoring for territories of interest, especially for the broad ocean area. For surveillance of ship targets at sea, a common and powerful approach is to take advantage of satellite synthetic aperture radar (SAR) systems. Currently, using satellite SAR images for ship classification is a challenging issue due to complex sea situations and the imaging variances of ships. Fortunately, the emergence of advanced satellite SAR sensors has shed much light on the SAR ship automatic target recognition (ATR) task, e.g., utilizing dual-polarization (dual-pol) information to boost the performance of SAR ship classification. Therefore, in this paper we have developed a novel cross-polarimetric interaction network (CPINet) to explore the abundant polarization information of dual-pol SAR images with the help of deep learning strategies, leading to an effective solution for high-performance ship classification. First, we establish a novel multiscale deep feature extraction framework to fully mine the characteristics of dual-pol SAR images in a coarse-to-fine manner. Second, to further leverage the complementary information of dual-pol SAR images, we propose a mixed-order squeeze–excitation (MO-SE) attention mechanism, in which the first- and second-order statistics of the deep features from one single-polarized SAR image are extracted to guide the learning of another polarized one. Then, the intermediate multiscale fused and MO-SE augmented dual-polarized deep feature maps are respectively aggregated by the factorized bilinear coding (FBC) pooling method. Meanwhile, the last multiscale fused deep feature maps for each single-polarized SAR image are also individually aggregated by the FBC. Finally, four kinds of highly discriminative deep representations are obtained for loss computation and category prediction. For better network training, the gradient normalization (GradNorm) method for multitask networks is extended to adaptively balance the contribution of each loss component. Extensive experiments on the three- and five-category dual-pol SAR ship classification dataset collected from the open and free OpenSARShip database demonstrate the superiority and robustness of CPINet compared with state-of-the-art methods for the dual-polarized SAR ship classification task.

A Deformable and Multi-Scale Network with Self-Attentive Feature Fusion for SAR Ship Classification

The identification of ships in Synthetic Aperture Radar (SAR) imagery is critical for effective maritime surveillance. The advent of deep learning has significantly improved the accuracy of SAR ship classification and recognition. However, distinguishing features between different ship categories in SAR images remains a challenge, particularly as the number of categories increases. The key to achieving high recognition accuracy lies in effectively extracting and utilizing discriminative features. To address this, we propose DCN-MSFF-TR, a novel recognition model inspired by the Transformer encoder–decoder architecture. Our approach integrates a deformable convolutional module (DCN) within the backbone network to enhance feature extraction. Additionally, we introduce multi-scale self-attention processing from the Transformer into the feature hierarchy and fuse these representations at appropriate levels using a feature pyramid strategy. This enables each layer to leverage both its own information and synthesized features from other layers, enhancing feature representation. Extensive evaluations on the OpenSARShip-3-Complex and OpenSARShip-6-Complex datasets demonstrate the effectiveness of our method. DCN-MSFF-TR achieves average recognition accuracies of 78.1% and 66.7% on the three-class and six-class datasets, respectively, outperforming existing recognition models and showcasing its superior capability in accurately identifying ship categories in SAR images.

Utilizing Elephant Herd-Inspired Spiking Neural Networks for Enhanced Ship Detection and Classification in Marine Scene Matching

In the realm of marine intelligence, effective ship classification across vast oceanic expanses is pivotal. Despite strides in conventional identification techniques, existing methods exhibit limitations in terms of effectiveness, robustness, and overall performance. This paper introduces a novel Elephant Herd optimization based Spiking Neural Networks (EHO-SNN) for discerning large ships, small vessels, and the absence of ships. Initial satellite images from the Airbus dataset capture ships at sea, subjected to preprocessing via the wavelet transform-based Retinex algorithm (WRA) to eliminate noise and fog artifacts. Deep learning mobile net facilitates feature extraction, while the Elephant Herd algorithm culls irrelevant features, honing in on the most pertinent ones. Finally, the classification through a spiking neural network, distinguishing between large ships, small vessels, and the absence of ships. Detected large and small ships are accurately positioned within a selected scene, while the absence of a ship terminates the process. The Proposed EHO-SNN model attains an impressive classification accuracy of 99.10%. Notably, it surpasses OMRCNN-SHD, Efficient Net, and AN-YOLOv4 by 1.15%, 12.30%, and 7.79%, respectively, thereby advancing overall accuracy in ship classification.

Capsize criteria in beam seas: Melnikov analysis vs. safe basin erosion

We study the problem of capsizing of a rolling ship in harmonic and random beam seas, by means of the Melnikov method and safe basin calculations. In the random excitation case, we consider an integro-differential Cummins-type model equation that takes into account the hydrodynamic memory. The non-linear restoring moment is modeled by a high-order polynomial and the Melnikov criteria are evaluated numerically. We also examine a variant of the classical Melnikov method in which the damping terms are incorporated into the unperturbed system and the perturbation takes a modified form. We compare the theoretical predictions with direct (Monte-Carlo) simulations of the safe basins for two existing ships. In the random excitation case, we quantify the erosion by means of a mean integrity index. For weak damping, the classical and modified Melnikov curves coincide and are in good agreement with the onset of the safe basin erosion. As damping increases the Melnikov curves become less and less conservative with respect to the onset of erosion. Finally, the potential of the Melnikov method to provide a ship classification tool is discussed.

DSNet: dual-stream network for fine-grained ship classification in optical remote sensing images

ABSTRACT The fine-grained ship classification (FGSC) task in remote sensing aims to distinguish subordinate ship categories. Due to the high similarity among different subcategories and the significant variations in pose, scale, rotation, and color within the same subcategory in the fine-grained ship datasets, the FGSC task is extremely challenging. To alleviate these issues, a novel approach, named Dual-Stream Network (DSNet), is proposed in this paper for FGSC. DSNet consists of two sub-branches: the Local Residual Branch (LRB) and the Global Representation Branch (GRB). Specifically, the LRB effectively extracts the most discriminative local fine-grained features of the target using Full-scale Skip Connections (FSC) and Stripe Pooling Add (SPA) modules. The GRB captures global contextual information through Swin-Transformer (Swin-T), establishing remote dependencies of the target and extracting global coarse-grained features. Furthermore, a Lightweight Fusion (LF) block is designed in the feature fusion module to combine the feature information from the two branches. This ensures that the discriminative global and local information complement each other without overwhelming one another, thereby effectively improving the performance of the model. Extensive experiments and analyses demonstrate that our proposed method achieves state-of-the-art performance on two mainstream FGSC datasets in remote sensing.

Maritime vessel classification based on a dual network combining EfficientNet with a hybrid network MPANet

AbstractShip classification is an important technique for enhancing maritime management and security. Visible and infrared sensors are generally employed to deal with the challenging problem and improve classification performance. Herein, a two‐branch feature fusion neural network structure is proposed to classify the visible and infrared maritime vessel images simultaneously. Specifically, in this two‐branch neural network, one branch is based on a deep convolutional neural network that is used to extract the visible image features, while the other is a hybrid network structure that is a multi‐scale patch embedding network called MPANet. The sub‐network MPANet can extract fine‐ and coarse‐grained features, in which the pooling operation instead of the multi‐head attention mechanism is utilized to reduce memory consumption. When there are infrared images, it is used to extract the infrared image features, otherwise, this branch is also utilized to extract visible image features. Therefore, this dual network is suitable with or without infrared images. The experimental results on the visible and infrared spectrums (VAIS) dataset demonstrate that the introduced network achieves state‐of‐the‐art ship classification performance on visible images and paired visible and infrared ship images.

Remote Sensing Image Harmonization Method for Fine-Grained Ship Classification

Target recognition and fine-grained ship classification in remote sensing face challenges of high inter-class similarity and sample scarcity. A transfer fusion-based ship image harmonization algorithm is proposed to overcome these challenges. This algorithm designs a feature transfer fusion strategy based on the combination of a region-aware instantiation and attention mechanism. Adversarial learning is implemented through an image harmony generator and discriminator module to generate realistic remote sensing ship harmony images. Furthermore, the domain encoder and domain discriminator modules are responsible for extracting feature representations of the foreground and background, and further align the ship foreground with remote sensing ocean background features through feature discrimination. Compared with other advanced image conversion techniques, our algorithm delivers more realistic visuals, improving classification accuracy for six ship types by 3% and twelve types by 2.94%, outperforming Sim2RealNet. Finally, a mixed dataset containing data augmentation and harmonizing samples and real data was proposed for the fine-grained classification task of remote sensing ships. Evaluation experiments were conducted on eight typical fine-grained classification algorithms, and the accuracy of the fine-grained classification for all categories of ships was analyzed. The experimental results show that the mixed dataset proposed in this paper effectively alleviates the long-tail problem in real datasets, and the proposed remote sensing ship data augmentation framework performs better than state-of-the-art data augmentation methods in fine-grained ship classification tasks.

Visual Ship Image Synthesis and Classification Framework Based on Attention-DCGAN

To improving ship image generation and classification tasks, a deep convolution generative adversarial network based on attention mechanism (ADCGAN) model was constructed. The rectified linear unit (ReLU) activation function was adopted, and three Deconv layers and Conv layers were added to both the generator and discriminator. Subsequently, an attention mechanism was added to the generator, while spectral normalization (SN) was added to the discriminator. Mean squared error (MSE) was used as loss function to stabilize the training process. Furthermore, ship classification tasks were performed using the generated ship images by end-to-end training of the classification network, enabling ship data augmentation and co-learning with other tasks. Experimental results on the Ship700 and Seaship7000 datasets demonstrate that the ADCGAN model can generate clear and robust ship images, with PSNR, LIPIPS, MS-SSIM values of 20.279 and 27.523, 0.596 and 0.096, 0.781 and 0.947, respectively. The effectiveness of the proposed method in ship image classification tasks was also verified, providing a data foundation for other collaborative tasks.

Enhancing object detection and classification using deep learning: A novel approach with annotated dataset and YOLO-C3GTR architecture

In the rapidly evolving field of computer vision, the need for advancements in object detection is paramount. For a variety of reasons, including security, maritime surveillance, and environmental monitoring, the identification and categorization of ships in aerial pictures is an essential component. In this study, two distinctive approaches are proposed to improve the accuracy of ship detection and categorization in satellite imagery. In the beginning, the dataset for ship detection that was provided by Airbus was separated into five distinct categories: oil tanker, bulk carrier, container ship, sand carrier, and general ship class. Setting up this division was done with the idea of increasing the precision of the ship classification in the imagery. Moreover, we deployed the YOLO-C3GTR model, which is part of our Object Detection framework and helped us to distinguish ships using the technique of Object Detection. The application of the methodology that we have proposed has the potential to significantly improve the precision of these systems when they are used in real-world scenarios and to make a novel addition to the field of ship identification and classification. We have used multiple algorithms of YOLOv5 tested on this dataset like TPHYOLOv5, YOLOv5x, YOLOv5l and our proposed architecture YOLO-C3GTR and it surpassed all the existing approaches by the mAP of 0.83. Furthermore, we intend to perform additional research in this field while simultaneously working to improve our technique. A comparison was made between the performance of the model and that of other deep learning approaches. The model was evaluated and trained with the categorized dataset.

An Improved SAR Ship Classification Method Using Text-to-Image Generation-Based Data Augmentation and Squeeze and Excitation

Synthetic aperture radar (SAR) plays a crucial role in maritime surveillance due to its capability for all-weather, all-day operation. However, SAR ship recognition faces challenges, primarily due to the imbalance and inadequacy of ship samples in publicly available datasets, along with the presence of numerous outliers. To address these issues, this paper proposes a SAR ship classification method based on text-generated images to tackle dataset imbalance. Firstly, an image generation module is introduced to augment SAR ship data. This method generates images from textual descriptions to overcome the problem of insufficient samples and the imbalance between ship categories. Secondly, given the limited information content in the black background of SAR ship images, the Tokens-to-Token Vision Transformer (T2T-ViT) is employed as the backbone network. This approach effectively combines local information on the basis of global modeling, facilitating the extraction of features from SAR images. Finally, a Squeeze-and-Excitation (SE) model is incorporated into the backbone network to enhance the network’s focus on essential features, thereby improving the model’s generalization ability. To assess the model’s effectiveness, extensive experiments were conducted on the OpenSARShip2.0 and FUSAR-Ship datasets. The performance evaluation results indicate that the proposed method achieves higher classification accuracy in the context of imbalanced datasets compared to eight existing methods.

Fine-grained ship image classification and detection based on a vision transformer and multi-grain feature vector FPN model

ABSTRACT In naval and civilian domains, meticulous ship classification and detection are paramount. Nevertheless, predominant research has gravitated toward leveraging Convolutional Neural Network (CNN)-centered methodologies, often overlooking the diverse granularity inherent in ship samples. In our pursuit to holistically extract features from ship images across varying granularities, we present a transformative architecture: the Vision Transformer and Multi-Grain Feature Vector Feature Pyramid Network (ViT-MGFV-FPN). This model synergistically melds the merits of MGFV-FPN with an augmented Vision Transformer (ViT) for a comprehensive image feature extraction. To cater to the extraction of broader image features whilst sidestepping the innate quadratic complexity of traditional ViT, we unveil an enhanced version christened the Global Swin Transformer. Concurrently, the MGFV-FPN is orchestrated to harness the prowess of CNNs in distilling intricate ship attributes. Rigorous empirical evaluations underscore our model’s superiority in juxtaposition with extant CNN and transformer-based paradigms for nuanced ship categorization.

DWSTr: a hybrid framework for ship-radiated noise recognition

The critical nature of passive ship-radiated noise recognition for military and economic security is well-established, yet its advancement faces significant obstacles due to the complex marine environment. The challenges include natural sound interference and signal distortion, complicating the extraction of key acoustic features and ship type identification. Addressing these issues, this study introduces DWSTr, a novel method combining a depthwise separable convolutional neural network with a Transformer architecture. This approach effectively isolates local acoustic features and captures global dependencies, enhancing robustness against environmental interferences and signal variability. Validated by experimental results on the ShipsEar dataset, DWSTr demonstrated a notable 96.5\% recognition accuracy, underscoring its efficacy in accurate ship classification amidst challenging conditions. The integration of these advanced neural architectures not only surmounts existing barriers in noise recognition but also offers computational efficiency for real-time analysis, marking a significant advancement in passive acoustic monitoring and its application in strategic and economic contexts.

Navigating Safety and Compliance in High-Voltage Shore Connection Systems: A Comprehensive Exploration of IEC/IEEE 80005-1 Standards and the Guidelines of Ship Classification Societies

This paper addresses the growing concern over air pollutant emissions (NOx, SOx, PM, CO2) from ocean-going vessels in harbor areas and the role of Onshore Power Supply (OPS) systems in mitigating these emissions during vessel berthing. However, the slow progress in global shore power facilities is attributed to safety- and specification-related concerns. Our study conducts a comprehensive analysis, comparing international shore power regulations, with a specific focus on the IEC/IEEE 80005-1 standard and guidelines from various ship classification societies. We introduce checklists, scoring tables, and spider diagrams to evaluate the regulatory content, highlighting the strengths and weaknesses of each approach. Furthermore, this paper emphasizes the significance of a well-defined operational process for high-voltage shore connection (HVSC) to ensure the safety of OPS operations. We present process diagrams for key operational stages, based on IEC/IEEE 80005-1 specifications and evaluation criteria. The ultimate goal of this research is to drive the global adoption of shore power and foster the establishment of shore power facilities worldwide. This aligns with the broader environmental protection objectives of achieving cleaner ports and reducing emissions for a sustainable future.

Shipyard’s Quality System involvement in the classification process at the new construction phase

The Quality Management System (QMS) of a shipyard is considered as a dynamic system which ameliorates in parallel with the evolution of the shipyard, having as purpose to optimize construction performance, to reduce risks, costs and time. The interaction and participation with external organizations play an important role in the cycle processes of maintenance and improvement of the Shipyard QMS. Bureau Veritas (BV) being a Ship Classification Society, contributes to the certification process through compliance with regard to BV technical rules and statutory requirements for each ship configuration. This paper illustrates the importance of the interaction between shipyard and class society starting at early design phase until delivery of the ship. Process described is based on specifics BV rules and New Building procedures which are continuously updated based on new international regulations, experiences, researches and developments. The pre-project process is founded on the definition of the scope of work, a thorough review of the contract, familiarization with the shipyard’s facilities, and the definition and agreement of all activities to be addressed throughout the entire construction. The construction process unfolds according to the agreements outlined during the pre-project phase. This part is specifically concentrated on Design Review (drawings and documents), Documentation System (procedures and methods), the Verification System (monitoring, control & reporting, witnessing, inspection & test), and the Management System (but not limited to); all of which are managed under a specific BV IT Tool. The result of all this is an efficient classification process that ensures ships remain safe, compliant, efficient, and environmentally friendly throughout their operating life.

MS3Net: a deep ensemble learning approach for ship classification in heterogeneous remote sensing data

ABSTRACT Maritime ship classification is essential for effectively monitoring oceanic activities but faces challenges when using heterogeneous remote sensing data. This research presents a novel dataset called Heterogeneous Ship Data, created by combining synthetic aperture radar (SAR) and optical satellite images of ships. The integration of multimodal data aims to harness the complementary advantages of SAR’s all-weather imaging capabilities and optical data’s higher interretability and shape discrimination. To leverage the heterogeneous dataset, this paper proposes an ensemble deep learning model called MS3Net (Multi-convolutional network using Spatial attention and Second-order pooling for Ship image classification). MS3Net integrates spatial attention mechanisms and second-order pooling. MS3Net has multiple convolutional branches, each tailored to extract distinct representations from the SAR and optical data through varied filter sizes and kernels. The spatial attention units focus the learning on the most informative parts of the image while suppressing irrelevant features. The second-order pooling captures higher-order interactions between feature elements to model complex relationships. A concatenation fusion strategy aggregates the diverse branch outputs into a joint multimodal feature representation for enhanced discrimination. Extensive experiments demonstrate MS3Net’s superior classification accuracy over prior state-of-the-art approaches. The proposed heterogeneous data representation coupled with the attention-based deep ensemble learning model contributes to maritime surveillance by enabling robust ship recognition across diverse sensing modalities.

Prediction-enabled path planning for multi-ship encounters in Oslofjord

Maritime navigation in multi-ship encounters presents challenges due to dynamic perturbations and complexity, which lead to elevated safety concerns. Conventional path-planning methods exhibit several issues. This paper addresses these issues by proposing a prediction-enabled path-planning method for multi-ship encounters in the Horten and Moss area within Oslofjord, Norway, the first industrial testbed for autonomous ferries nationwide. The method leverages action classification and trajectory projection techniques to enhance path planning with a more informed decision-making process. A convolution neural network is employed for the binary classification of the own ship’s action classes, and a dynamic time-warping approach is applied to predict the future positions of the target ships based on trajectory similarity. Experiments utilizing Automatic Identification System data from 2013 to 2019 demonstrated the method’s effectiveness. Classification results show a satisfactory F1 score, and comparative evaluations with the classic A* method showcase superior performance. Real-case tests affirm the method’s ability to provide a trackable path while ensuring a safe distance between the own ship and target ships.

A Unified Multiple Proxy Deep Metric Learning Framework Embedded With Distribution Optimization for Fine-Grained Ship Classification in Remote Sensing Images

A Unified Multiple Proxy Deep Metric Learning Framework Embedded With Distribution Optimization for Fine-Grained Ship Classification in Remote Sensing Images