Electronic Navigational Chart Research Articles

Service Quality of Inland Electronic Navigational Charts on the Yangtze River

As a golden waterway in China, the Yangtze River is one of the busiest waterways in the world. The Changjiang Waterway Bureau has made inland electronic navigational charts (I-ENC) of the Yangtze River from Yibin to Liuhekou. It assists ships in safe navigation and provides information on waterway elements for analysis and prediction. Compared with traditional navigation and information methods, ENCs better promote the safety and efficiency of inland waterway navigation, thereby protecting the environment. The primary tool of this study is the questionnaire, including the basic information, business services, data services, available services, and product services of the Yangtze River I-ENC. This study analyzed the questionnaire combined with on-the-spot investigation, focusing on understanding respondents’ current views on the Yangtze River I-ENC to improve service quality. A total of 885 respondents completed the questionnaire from June 2021 to August 2021. The results show that the Yangtze River I-ENC mainly expands related products, such as Electronic Chart Display and Information System (ECDIS), mobile application, WeChat small program, internet online navigational charts, and paper navigational charts. Mobile application is the most popular among respondents. The primary purpose of I-ENC at the present stage is to assist navigation and improve navigation safety.

A Spatial Relation Model of Three-Dimensional Electronic Navigation Charts Based on Point-Set Topology Theory

Spatial relation models are the basis for realising three-dimensional spatial analysis. More researchers are now focusing on models that combine topological relations with distance or directional relations; however, a model that unifies all three relations has not yet been developed. In particular, it is more effective to use different spatial relations between features with different spatial characteristics in three-dimensional electronic navigation charts (3D ENC). Therefore, this paper proposes a 3D ENC feature spatial relation model (3DSRM) based on point-set topology theory, which combines 3D topological relations, distance relations and directional relations, and uses a unified model framework to describe 64 topological relations of 3D ENC features from both horizontal and vertical directions. Through the comparison and derivation of feature topological relations, it is demonstrated that the model can distinguish 3D spatial topological relations more comprehensively, realise the mutual derivation between spatial relations and spatial features, and improve the robustness of spatial relations judgement. The model can be used to judge the topological relations between features, realise 3D topological relation checking and topological creation of complex features, and improve the accuracy and interactivity of 3D ENC.

A Novel Algorithm for Ship Route Planning Considering Motion Characteristics and ENC Vector Maps

Global route planning is a pivotal function of unmanned surface vehicles (USVs). For ships, the safety of navigation is the priority. This paper presents the VK-RRT* algorithm as a way of designing the planned route automatically. Different from other algorithms or studies, this study employs electronic navigation chart (ENC) vector data instead of grid maps as the basis of the search, which reduces data error when converting the vector map into the grid map. In addition, Delaunay triangulation is employed to organize vector data, in which the depth value is taken as a factor to ensure the safety of the planning route. Furthermore, the initial planned route is not suitable for ship tracking as it does not consider the ship motion characteristics. Therefore, the planned route needs to be further optimized. In the final part, we also conducted experiments to verify the effectiveness and advantages of the proposed algorithm. The results show that the proposed algorithm could reduce the lengths of paths by about 23% on average and save planning time; these are largely dependent on the environment.

Usporedba podataka hidrografskog premjera s podacima o dubinama mora dobivenih iz javnih izvora

A hydrographic survey is a standardized procedure for collecting data for the production of nautical charts and publications. It is a lengthy and costly procedure, so the survey is carried out depending on the capabilities of hydrographic organizations. It is known that relatively large parts of the world's oceans are very poorly covered by hydrographic surveys. To increase the amount of data collected, the International Hydrographic Organization (IHO) has introduced the concept of crowdsourced bathymetry (CSB). Under the CSB concept, all vessels meeting certain minimum technical requirements (carrying a global navigation satellite system and a single beam echo sounder) can participate in voluntary bathymetric data collection. The paper analyzes the method of collecting bathymetric data from CSB. The depth data collected as part of the CSB are compared with official data displayed on electronic navigational charts (ENC) in the United States of America. Four sea areas were selected in which 104 depths were compared at the same positions, and categorization was also made according to the criterion of navigational importance, i.e., the category zones of confidence (CATZOC). By comparing the official depth data from the hydrographic survey with the depth data collected from public sources for the same positions, their mutual relationships were established, from which it can be concluded that the CSB data, despite its limitations, is a very valuable supplement to the existing official data.

Coastal Bathymetric Sounding in Very Shallow Water Using USV: Study of Public Beach in Gdynia, Poland.

The bathymetric surveys executed with a use of small survey vessels in limited water areas, including offshore areas, require precise determination of the geospatial coordinates of the seabed which is a synthesis of, among others, determining the position coordinates and measuring the depth. Inclination of the seabed and the declining depth make manoeuvring of the sounding vessel, e.g., a hydrographic motorboat or Unmanned Survey Vehicle (USV), in shallow water impossible. Therefore, it is important to determine the minimal depth for the survey resulting from the draught of the sounding vessel and the limits of the sounding area. The boundaries also result from the dimensions of the sounding vessel, its manoeuvring parameters and local water level. Type of the echosounder used in the bathymetric survey is a decisive factor for the sounding profile planning and the distances between them and the survey vessel for the possibility performing the measurements in shallow water. Electronic Navigational Chart (ENC) was used to determine the water area's boundaries, and the safety contours were determined on the basis of the built Digital Sea Bottom Model (DSBM). The safety contour, together with the vessel's dimensions, its manoeuvring parameters and the hydrometeorological conditions, limit the offshore area in which the measurement can be performed. A method of determining boundaries of the survey performed by a USV equipped with SingleBeam EchoSounder (SBES) on survey lines perpendicular to the coastal line are presented in the paper in order to cover the water area with the highest amount of measurement data, with the USV's navigational safety taken into consideration. The measurements executed on the municipal beach served verification of the DSBM.

Increasing Efficiency of Nautical Chart Production and Accessibility to Marine Environment Data through an Open-Science Compilation Workflow

Electronic Navigational Chart (ENC) data are essential for safe maritime navigation and have multiple other uses in a wide range of enterprises. Charts are relied upon to be as accurate and as up-to-date as possible by the vessels moving vast amounts of products to global ports each year. However, cartographic generalization processes for updating and creating ENCs are complex and time-consuming. Increasing the efficiency of the chart production workflow has been long sought by the nautical charting community. Toward this effort, approaches must consider intended scale, data quality, various chart features, and perform consistently in different scenarios. Additionally, supporting open-science initiatives through standardized open-source workflows will increase marine data accessibility for other disciplines. Therefore, this paper reviews, improves, and integrates available open-source software, and develops new custom generalization tools, for the semi-automated processing of land and hydrographic features per nautical charting specifications. The robustness of this approach is demonstrated in two areas of very different geographic configurations and the effectiveness for use in nautical charting was confirmed by winning the first prize in an international competition. The presented rapid data processing combined with the ENC portrayal of results as a web-service provides new opportunities for applications such as the development of base-maps for marine spatial data infrastructures.

Analysis and Visualization of Vessels’ RElative MOtion (REMO)

This research is a pilot study to develop a maritime traffic control system that supports the decision-making process of control officers, and to evaluate the usability of a prototype tool developed in this study. The study analyzed the movements of multiple vessels through automatic identification system (AIS) data using one of the existing methodologies in GIScience, the RElative MOtion (REMO) approach. The REMO approach in this study measured the relative speed, delta-speed, and the azimuth of each vessel per time unit. The study visualized the results on electronic navigational charts in the prototype tool developed, V-REMO. In addition, the study conducted a user evaluation to assess the user interface (UI) of V-REMO and to future enhance the usability. The general usability of V-REMO, the data visualization, and the readability of information in the UI were tested through in-depth interviews. The results of the user evaluation showed that the users needed changes in the size, position, colors, and transparency of the trajectory symbols in the digital chartmap view of V-REMO for better readability and easier manipulation. The users also indicated a need for multiple color schemes for the spatial data and more landmark information about the study area in the chartmap view.

Resolving problems in symbol identification in compilation of electronic navigational charts utilising paper charts

AbstractElectronic navigational charts (ENCs) can be compiled using existing paper charts to improve their coverage of the world's oceans. However, in the process of assigning symbols on ENCs, in some cases the software uses the same symbol for different paper chart symbols. This could ultimately compromise maritime safety. Addressing this issue, this paper describes a methodology for developing a new tool that complements the efficient production of ENCs using paper charts. First, the ENC product was produced utilising CARIS S-57 Composer. After considering the difficulties in assigning symbols through the compilation process, a new web application named SYMO EXPERT was introduced. It was developed using Firebase Realtime Database and React app. A questionnaire was prepared to collect data about the time factor and accuracy of using SYMO EXPERT. Results showed that it supports the users in selecting relevant symbols efficiently with an accuracy of up to 98%.

USING ELECTRONIC NAVIGATIONAL CHART FOR 3D BATHYMETRIC MODEL OF THE PORT OF NAPLES

Abstract. Nautical charts generally report fundamental knowledge for the safety of navigation. This information also includes sea depth data reported as depth points or contour lines, which can be used to build a 3D model of the seabed. However, there are different interpolation methods for creating digital depth models, and there is no way to know in advance which of them is the best performing. The aim of this work is to compare different spatial interpolation methods applied on a dataset concerning the seabed of the Port of Naples (Italy) and extracted from the Electronic Navigational Chart (ENC) produced by the Hydrographic Institute of the Italian Navy, in scale 1:10.000. Four deterministic interpolation methods, i.e. Inverse Distance Weighting (IDW), Global Polynomial Interpolation (GPI), Local Polynomial Interpolation (LPI), Radial Basis Function (RBF), and two stochastic interpolation methods, i.e. Ordinary Kriging (OK) and Universal Kriging (UK), are applied using Geographic Information System (GIS) software. Since each method requires to set specific parameters and different options are available, e.g. the order of the polynomial function for GPI and LPI, or semi-variograms for OK and UK, twenty-three models are generated. The result quality is evaluated by Leave-One-Out cross-validation and the statistics of the residuals produced by each interpolation method in the measured points are compared and analysed. The experiments confirm that the stochastic approach is more versatile compared to deterministic approach and can produce better results, as it is testified by the great performance of the Ordinary Kriging, which produces the most accurate 3D models.

Autonomous Machinery Management for Supervisory Risk Control Using Particle Swarm Optimization

Safe navigation for maritime autonomous surface ships (MASS) is a challenging task, and generally highly dependent on effective collaboration between multiple sub-systems in environments with various levels of uncertainty. This paper presents a novel methodology combining risk-based optimal control and path following with autonomous machinery management (AMM) for MASS navigation and supervisory risk control. Specifically, a risk-aware particle swarm optimization (PSO) scheme utilizes “time-to-grounding” predictions based on weather data and electronic navigational charts (ENC) to simultaneously control both the ship’s motion as well as the machinery system operation (MSO) mode during transit. The proposed autonomous navigation system (ANS) is comprised of an online receding horizon control that uses a PSO approach from previous works, which produces a dynamic risk-aware path with respect to grounding obstacles from a pre-planned MASS path, subsequently given as the input to a line-of-sight guidance controller for path following. Moreover, the MSO mode of the AMM system is simultaneously selected and assigned to explicit segments along the risk-aware path throughout the receding horizon, which effectively introduces into the optimization scheme an additional safety layer as well as another dimension for risk or resource minimization. The performance of the resulting ANS is demonstrated and verified through simulations of a challenging scenario and human assessment of the generated paths. The results show that the optimized paths are more efficient and in line with how human navigators would maneuver a ship close to nearby grounding obstacles, compared to the optimized paths of selected previous works.

Marine protected areas and electronic navigational charts: legal foundation, mapping methods, IHO S-122 portrayal, and advanced navigation services

A strategic instrument for the sustainable conservation of the fragile marine ecosystem is the designation of Marine Protected Areas (MPAs), within which various regulations exist for the protection of highly vulnerable species and habitats. These regulations can be depicted on Electronic Navigational Charts (ENCs) based on the new International Hydrographic Organization (IHO) S-100 series of standards, which support Marine Information Overlays (MIOs) that enrich the portrayed information by including both static and dynamic information, such as vessels traffic, tides, currents, and weather conditions, as well as essential information for the regulation of MPAs. Although, the new IHO S-122 Product Specification introduced specifically for the MPAs has been developed to encapsulate geospatial information for these regulations, the present edition does not specify portrayal. This paper reviews the legal foundation for the protection of marine mammals as well as the mapping methods used in selected study cases and builds upon these to present new, intuitive portrayal symbols for depicting the type of MPAs in combination with the regulations to be enforced on ENCs. Moreover, to support the global efforts for the protection of marine biodiversity, contemporary navigation systems aboard vessels can be used to enforce environmental regulations, and operations centers ashore can also monitor vessels’ passage and activities in MPAs. In that respect, this paper also discusses the concepts of Ecosystem Protection Zones and Environmental Risk Contours that can facilitate environmental risk-based voyage planning and preventive alarm services through Electronic Chart Display and Information Systems (ECDIS).

A method of constructing a dynamic chart depth model for coastal areas.

The depth is important for vessel navigation at sea. Currently, most vessels use electronic navigation charts to navigate at sea. In coastal areas, especially close to shallow water areas, the dynamic change of the water level is very important to safe navigation. Ships calculate the change of water level by using up-to-date tide tables, to obtain the dynamic water depth in the channels. However, the depth caused by the tide and non-tidal components may reach several meters in some seas, causing the dynamic depth below the safety depth, which can easily lead to grounding of vessels stranding accidents. The channel is regularly dredged to achieve navigational depth. Without regular dredging, the offshore non-channel area becomes the common area of ship grounding. The dynamic chart depth model studied in this article can provide real-time depth, which serves the ships navigation in the non-channel. The model incorporates the chart depth and the dynamic water levels on the same reference datum. The chart depth is from the electronic navigational chart depth. The dynamic water levels are constructed by the simulated tidal levels and continuous series of nontidal residual. We then designed a deviation correction method to reduce the discrepancy of the simulated tidal level with the actual water level, including datum offset correction and residual water level correction. Finally, by merging the revised dynamic water levels with the electronic navigational chart depth, we obtained the dynamic chart depth model of the study region.

Assessment of the Possibility of Using a Waterway for Operation of Autonomous Ships

The development of autonomous navigation is an important element in terms of increasing the efficiency of the water transport system, and the current level of technology and technology allows building ships that will operate without a crew or with remote control. The performed literary analysis of scientific sources of information confirms the significant lack of research aimed at the development of waterway infrastructure for unmanned ships. The study described in this paper is aimed at developing a design criterion that determines the possibility of using the waterway for the operation of autonomous ships. Data on the movement and density of ships for the waters of the Gulf of Finland according to the data of Automatic Identification System are presented. The analysis of vessel density in this work was carried out using the DBSCAN mathematical algorithm. It is proposed to use the concept and term "knowledgeable" to include sections of the waterway in the zone of autonomous navigation. The involved experts assessed five criteria in terms of their significance: the availability of data on navigation on the selected section of the waterway, the availability of electronic navigation charts, the availability of hydrometeorological information, the availability of technical means of communication and navigational fencing. As a continuation of the research, it is proposed to study many qualitative and quantitative characteristics of both the area of the water area and the specialized equipment installed on it, since the operation of autonomous ships requires a more complex technical and information infrastructure.

Semantic Recognition of Ship Motion Patterns Entering and Leaving Port Based on Topic Model

Recognition and understanding of ship motion patterns have excellent application value for ship navigation and maritime supervision, i.e., route planning and maritime risk assessment. This paper proposes a semantic recognition method for ship motion patterns entering and leavingport based on a probabilistic topic model. The method enables the discovery of ship motion patterns from a large amount of trajectory data in an unsupervised manner and makes the results more interpretable. The method includes three modules: trajectory preprocessing, semantic process, and knowledge discovery. Firstly, based on the activity types and characteristics of ships in the harbor waters, we propose a multi-criteria ship motion state recognition and voyage division algorithm (McSMSRVD), and ship trajectory is divided into three sub-trajectories: hoteling, maneuvering, and normal-speed sailing. Secondly, considering the influence of port traffic rules on ship motion, the semantic transformation and enrichment of port traffic rules and ship location, course, and speed are combined to construct the trajectory text document. Ship motion patterns hidden in the trajectory document set are recognized using the Latent Dirichlet allocation (LDA) topic model. Meanwhile, topic coherence and topic correlation metrics are introduced to optimize the number of topics. Thirdly, a visualization platform based on ArcGIS and Electronic Navigational Charts (ENCs) is designed to analyze the knowledge of ship motion patterns. Finally, the Tianjin port in northern China is used as the experimental object, and the results show that the method is able to identify 17 representative inbound and outbound motion patterns from AIS data and discover the ship motion details in each pattern.

Development of Ship Route-Planning Algorithm Based on Rapidly-Exploring Random Tree (RRT*) Using Designated Space

Ship route planning is a crucial activity that must consider not only the safety of the ship but also the safe passage of nearby ships in the same space and time. This study aims to provide general route-planning guidance to shipping traffic by improving conventional sampling-based route-planning algorithms in accordance with the maritime environment from a ship operator’s perspective. The obstacle safety margin in a marine environment can be reflected in a binary image map space based on an electronic navigational chart. Consequently, an initial route was created using the probabilistic road map (PRM) algorithm in the configured map space to increase the speed of the conventional sampling-based route-planning algorithm. Based on the initial route created, a designated space—that is, a multi-elliptical area—was created to limit the route-search range. After searching the final route in the designated space based on the rapidly-exploring random tree (RRT*) algorithm, optimal route planning could be achieved by generating a collision-free space graph to remove unnecessary nodes from the searched final route. The simulation results showed that the route was shortened by approximately 33.7 km compared with the conventional RRT* algorithm, and the calculation time was shortened by approximately 2.5 times.

Formation of MASS Collision Avoidance and Path following Based on Artificial Potential Field in Constrained Environment

It is essential to promote the intelligence and autonomy of Maritime Autonomous Surface Ships (MASSs). This study proposed an automatic collision-avoidance method based on an improved Artificial Potential Field (APF) with the formation of MASSs (F-MASSs). Firstly, the navigation environment model was constructed by the S-57 Electronic Navigation Chart (ENC) data in Tianjin Port. The Formation Ship State Parameter (FSSP) definition was proposed for the port environment under multiple constraints that considered the navigation conditions of the MASSs. The formation pattern transformation was settled by changing the formation ship state parameter. Considering the constraints of an ‘unmanned–manned’ encounter situation, the static obstacles, and the design of the channel area improved artificial potential method for the formation. Finally, the simulation experiment was carried out in the sea near Tianjin Port to verify the effectiveness of the algorithm under multiple constraints. The results indicate that the method can satisfy the integrated operation of collision avoidance and path following in a constrained environment, and it can support the application of merchant F-MASS autonomous navigation in the future.

A New Global Bathymetry Model: STO_IEU2020

To address the limitations in global seafloor topography model construction, a scheme is proposed that takes into account the efficiency of seafloor topography prediction, the applicability of inversion methods, the heterogeneity of seafloor environments, and the inversion advantages of sea surface gravity field element. Using the South China Sea as a study area, we analyzed and developed the methodology in modeling the seafloor topography, and then evaluated the feasibility and effectiveness of the modeling strategy. Based on the proposed modeling approach, the STO_IEU2020 global bathymetry model was constructed using various input data, including the SIO V29.1 gravity anomaly (GA) and vertical gravity gradient anomaly (VGG), as well as bathymetric data from multiple sources (single beam, multi-beam, seismic, Electronic Navigation Chart, and radar sensor). Five evaluation areas located in the Atlantic and Indian Oceans were used to assess the performance of the generated model. The results showed that 79%, 89%, 72%, 92% and 93% of the checkpoints were within the ±100 m range for the five evaluation areas, and with average relative accuracy better than 6%. The generated STO_IEU2020 model correlates well with the SIO V20.1 model, indicating that the proposed construction strategy for global seafloor topography is feasible.

WITHDRAWN: Evaluation and performance of satellite-derived bathymetry algorithms in turbid coastal water: A case study of Vengurla rocks

The coastal region bathymetry is increasingly becoming necessary for emerging needs of navigation and development along coasts. Satellite-derived bathymetry (SDB) has been examined as a viable alternative for hydrographic surveys for the past few decades to reduce the data acquisition efforts in coastal regions and augmentation of periodic updating of Electronic Navigational Charts (ENCs). The previous studies have applied SDB algorithms in less complex waters due to the limitations of SDB algorithms in turbid and varying shallow waters. This paper analyses three different medium resolution satellite imagery data to derive bathymetry in navigably very complex and highly turbid region Vengurla Rocks, situated at the west coast of India. The objective of the study was to evaluate the best suitable technique for SDB in turbid water. The bathymetry product images have been derived using the two most commonly utilized Log Ratio, and Linear Ratio transformation; ENVI 5.3 semi-automated tool using Ratio transform; and three machine learning (ML) regression algorithms using Linear Regressor, Random Forest (RF) Regressor and Support Vector (SVR) Regressor. Among the applied transform and algorithms, the RF algorithm using OLI/Landsat-8 data performed the best, resulting in R 2 of 0.88, RMSE of 2.78 m, and MAE 1.83 m. This work established that open source images of sensor OLI/Landsat-8 satellite provide the best results of SDB estimation in complex turbid water by applying Machine Learning algorithms. However, extreme turbid and complex regions resulted in more erroneous SDB estimation specifying the need for refining algorithms using bio-optical parameters. • Satellite derived bathymetry in complex turbid water. • Challenges in retrieval of water depth. • Depth estimation using machine learning algorithms. • The comparison of Machine Learning algorithms in Satellite-Derived Bathymetry.

Cyber-resilience for marine navigation by information fusion and change detection

Cyber-resilience is an increasing concern for autonomous navigation of marine vessels. This paper scrutinizes cyber-resilience properties of marine navigation through a prism with three edges: multiple sensor information fusion, diagnosis of not-normal behaviours, and change detection. It proposes a two-stage estimator for diagnosis and mitigation of sensor signals used for coastal navigation. Developing a Likelihood Field approach, the first stage extracts shoreline features from radar and matches them to the electronic navigation chart. The second stage associates buoy and beacon features from the radar with chart information. Using real data logged at sea tests combined with simulated spoofing, the paper verifies the ability to timely diagnose and isolate an attempt to compromise position measurements. A new approach is suggested for high level processing of received data to evaluate their consistency, which is agnostic to the underlying technology of the individual sensory input. A combined generalized likelihood ratio test using both parametric Gaussian modelling and Kernel Density Estimation is suggested and compared with a detector using only either of two. The paper shows how the detection of deviations from nominal behaviour is possible when the navigation sensor is under attack or defects occur.

Collision Risk Situation Clustering to Design Collision Avoidance Algorithms for Maritime Autonomous Surface Ships

The reliability of collision avoidance systems for Maritime Autonomous Surface Ships is one of the most critical factors for their safety. In particular, since many ship collisions occur in coastal areas, it is crucial to ensure the reliability of collision avoidance algorithms in geographically limited coastal waters. However, studies on maritime autonomous surface ships collision avoidance algorithms mainly focus on the traffic factor despite the importance of the geographic factor. Therefore, this study presents a methodology for establishing a practical collision avoidance system test bed, considering the geographic environment. The proposed methodology is a data-driven approach that objectively categorizes collision risk situations by extracting these risks using Automatic Identification System (AIS) and Electronic Navigational Chart (ENC) data, followed by clustering algorithms. Consequently, the research results present a direction for establishing test beds from the perspective of geographic and traffic factors.