Electronic Navigational Chart Research Articles

Optimal path planning for a ship in coastal waters with deep Q network

With the development of autonomous ships, complete automation of passage planning has become an imminent priority. However, existing A* algorithms have the disadvantage of generating paths close to land because they prioritize minimizing the navigation distance. Therefore, this study proposes a method based on a deep Q network to effectively implement reward-and-penalty strategies considering required navigation areas and non-navigable areas throughout the port-to-port distance. First, the Busan and Gwangyang Ports were selected as the target areas and a container ship was selected as the target ship. Initially, non-navigable and reward areas were designated based on the water depth and electronic navigational chart information. Thereafter, we conducted experiments using algorithms in three types of environments: normal conditions, turbulent weather, and obstacle-involved environments. Furthermore, we employed the Douglas–Peucker algorithm to eliminate excessive waypoints. Experimental results demonstrated that the path planning of a ship obtained using a deep Q network involved more efficient and safer decisions for ship navigation. Furthermore, the navigation distance was reduced by 1.77% compared to the passage plan used by actual ships. The proposed approach is advantageous for automatically deriving the optimal mid-range path of ships and can thus contribute toward improving maritime safety and efficiency.

Exploring the possibility of adding DGGS support to the S-100 Universal Hydrographic Data Model

reference systems. A DGGS is a spatial reference system consisting of multiple layers of grids with increasing resolution which partition the globe into polygon shaped cells of equal area. Individual cells can be easily identified and basic Geographic Information System (GIS) operations can be performed on data stored within the cells. Advantages of using DGGS for spatial data include the ability to integrate data layers of different data types in a statistically uniform way, the possibility to avoid distortions caused from projection, and the capability to scale analysis across multiple resolution levels. The benefits of using DGGS for hydrographic data, specifically Electronic Navigational Charts (ENC) are examined. The addition of DGGS to S-100 would provide a uniform gridding system for ENC cells, and would eliminate distortions in the Polar Regions caused when projecting rectangular cells based on latitude and longitude. The Open Geospatial Consortium (OGC) led a pilot project for which one of the participants developed a server that offers S-100 marine protected area data organized according to DGGS. Because of this success and the availability of open-source software for the implementation of DGGS, the BSH (German Federal Maritime and Hydrographic Agency) investigated the feasibility and possible benefits of using Discrete Global Grid Systems for S-100 data. The outcome was successful. However, it is recognized that DGGS as a standard is not yet advanced enough and the available software tools are inadequate for wide implementation. More investigation needs to be done, and additionally the best grid shape, orientation and aperture for a uniform grid for hydrographic data need to be determined. Overall, DGGS should be considered for future versions of S-100, the new universal hydrographic data model, because the benefits for ENCs and hydrographic data are clear and in the future, it is expected that DGGS will revolutionize GIS.

Dynamic Projection Method of Electronic Navigational Charts for Polar Navigation

Electronic navigational charts (ENCs) are geospatial databases compiled in strict accordance with the technical specifications of the International Hydrographic Organization (IHO). Electronic Chart Display and Information System (ECDIS) is a Geographic Information System (GIS) operated by ENCs for real-time navigation at sea, which is one of the key technologies for intelligent ships to realize autonomous navigation, intelligent decision-making, and other functions. Facing the urgent demand for high-precision and real-time nautical chart products for polar navigation under the new situation, the projection of ENCs for polar navigation is systematically analyzed in this paper. Based on the theory of complex functions, we derive direct transformations of Mercator projection, polar Gauss-Krüger projection, and polar stereographic projection. A rational set of dynamic projection options oriented towards polar navigation is proposed with reference to existing specifications for the compilation of the ENCs. From the perspective of nautical users, rather than the GIS expert or professional cartographer, an ENCs visualization idea based on multithread-double buffering is integrated into Polar Region Electronic Navigational Charts software, which effectively solves the problem of large projection distortion in polar navigation applications. Taking the CGCS2000 reference ellipsoid as an example, the numerical analysis shows that the length distortion of the Mercator projection is less than 10% in the region up to 74°, but it is more than 80% at very high latitudes. The maximum distortion of the polar Gauss-Krüger projection does not exceed 10%. The degree of distortion of the polar stereographic projection is less than 1% above 79°. In addition, the computational errors of the direct conversion formulas do not exceed 10−9 m throughout the Arctic range. From the point of view of the computational efficiency of the direct conversion model, it takes no more than 0.1 s to compute nearly 8 million points at 1′×1′ resolution, which fully meets the demand for real-time nautical chart products under information technology conditions.

METHODS FOR SATELLITE DERIVED BATHYMETRY FROM SENTINEL-2 IMAGES: A COMPARISON

Abstract. In recent decades, research has been developed to estimate near-shore bathymetry depth values using satellite imagery. Visible and infrared bands are used to derive elevation profile estimates, so to obtain bathymetric in rapid way without mobilisation of persons or equipment and saving the costs. For consequence, Satellite Derived Bathymetry (SDB) is seen as a valid approach for shallow waters survey: strongly supported by the activity of scholars and researchers, multiple methods are available in the literature. This article aims to investigate and compare different SDB methods for sea depth extraction from Sentinel-2 satellite multispectral images, with particular attention to the accuracy of the results. The experiments are conducted on imagery including Blue, Green, Red and Near Infrared bands, with 10 m resolution, concerning the Bay of Pozzuoli (Italy). After removing the glint, the effects caused by the reflection of sunlight through single scattering from sea surface, three methods are applied: Band Ratio method (BRM), 3rd-degree polynomial regression line method (3DPM), and principal component analysis method (PCAM). 3DPM can be seen as a variant of the BRM where the linear law that interprets the correlation between the band ratio values and the depth values is replaced by the third order function. Models are trained using depth data extracted from an Electronic Navigational Chart (ENC) at 1:7,500 scale, which is also used to verify result accuracy. The experiments demonstrate that the 3DPM is better able to obtain a more precise bathymetric model, confirming the greater adaptability of the 3rd order function to interpretate the variability of the interaction of light with water along the water column.

Path Planning of Unmanned Surface Vehicle Based on Improved Sparrow Search Algorithm

In order to solve the problem of many constraints and a complex navigation environment in the path planning of unmanned surface vehicles (USV), an improved sparrow search algorithm combining cubic chaotic map and Gaussian random walk strategy was proposed to plan it. Firstly, in the population initialisation stage, cubic chaotic map was used to replace the random generation method of the traditional sparrow search algorithm to optimise the uneven initial distribution of the population and improve the global search ability of the population. Secondly, in the late iteration of the algorithm, the standard deviation of fitness is introduced to determine whether the population is trapped in the local optimum. If true, the Gaussian random walk strategy is used to perturb the optimal individual and assist the algorithm to escape the local optimum. Thirdly, the chosen water environment is modelled, and the navigation information of the original inland electronic navigation chart (ENC) is preprocessed, gridised, and the obstacle swelling is processed. Finally, the path planning experiments of USV are carried out in an inland ENC grid environment. The experimental results show that, compared with the traditional sparrow search algorithm, the average fitness value of the path planned by improved sparrow search algorithm is reduced by 14.8% and the variance is reduced by 49.9%. The path planned by the algorithm is of good quality and high stability and, combined with ENC, it can provide a reliable path for USV.

Overview of the Development of Nautical Charts

Nautical charts are one of the basic aids for safe navigation. Their development went through different phases and is related to the development of technology. The development of nautical charts has gone through certain phases. One can talk about the phases of the development of paper and electronic nautical charts. Paper charts have evolved from the dawn of maritime navigation (or from its earliest periods) to the advent of electronic charts. Recent technological developments have enabled the creation and use of electronic nautical charts in the formats of Raster Navigational Chart (RNC) and Electronic Navigational Chart (ENC). ENCs now take precedence over paper charts and RNCs and will gradually replace RNCs and paper charts on some types of SOLAS ships. The International Hydrographic Organization (IHO) has developed standards for paper, raster, and vector charts. After developing standards for existing ENCs, the IHO has developed a set of standards called S-100 as the basis for developing a new type of ENC. These charts will soon replace the existing ENC. This paper provides an overview of the development of nautical charts with a particular emphasis on the IHO standards.

The tasks for bathymetric investigations and cartographic support of the northern sea high latitude routes in the East Siberian Sea

The current state and issues of bathymetric investigations of the East Siberian Sea are examined in this study. The main sources of bathymetric data are characterized. The possibilities to solve these issues in order to improve the efficiency of the oncoming bathymetric investigation in the East Siberian Sea for supporting the urgent practical tasks of the Russian Federation concerning the Northern Sea high latitude routes are discussed. The importance of a new hydrographic investigation through the high latitude routes in the East Siberian Sea in order to provide the possibility of year-round navigation of the large-tonnage Arc7‑class icebreaking LNG carriers is especially emphasized. Compiling of the new coastal electronic navigation charts for the new Northern Sea high latitude routes is stated as one of the main priorities. The lack of coastal electronic navigation charts of the high latitude routes in the East Siberian Sea will present a challenge for the establishing of year-round navigation for high ice-capable Arc7‑class LNG carriers during the coming several years. The drafting of high latitude routes must also consider the seafloor gas venting in the East Siberian Sea. The satellite remote sensing data from passive microwave radiometers and optical sensors using «modis & amsr2» technology provided by the University of Bremen ensures the complementary observations of sea ice concentration in the eastern part of the East Siberian Sea. The re-analysis of data from microwave radiometers AMSR‑2 beginning from 2018 provides the conclusion about the autumn degradation of the Aion ice massif. The analysis of the sea-ice concentration of the Aion ice massif during autumn–winter of 2022, the most severe in the last 5 years, allows us to give a recommendation concerning the new high latitude route in the East Siberian Sea. This route passes along the northern coast of Vrangel island into the Chukchi Sea and it is more efficient for large-tonnage Arc7‑class icebreaking LNG carriers ensuring year-round navigation in the East Siberian Sea. It is stated that hydrographic investigations carried out on the sections of the Northern Sea Route must adhere to the requirements of the International Hydrographic Organization. The urgency of developing the state integrated bathymetric database for the Arctic Ocean including the Arctic Seas data along with the necessity of providing all Russian bathymetric data acquired in the Arctic region to the assigned national centre is discussed. The FKU 280 ZKP VMF is proposed as such national centre. The importance of coastal electronic navigation charts for the high latitude routes in the East Siberian Sea created on the basis of modern technology is emphasized.

Methodological proposal for the standardization of the Electronic Navigational Chart scheme in the Caribbean Sea

Since the approval of the use of Electronic Navigational Charts (ENC) as equivalent to paper nautical charts, hydrographic services worldwide began their production following existing cartographic schemes. This paper proposes to standardize ENC production schemes at the regional scale through a regular grid system, which unifies the scale of compilation and cell size by navigational purpose. The implementation of this system requires defining the origin of the grid and facilitates the nomenclature of the ENCs. Additionally, this standardization would help for the harmonized production of ENCs by improving their coverage. The proposed methodology is used to formulate an ENCs scheme in the Caribbean Sea, which is part of the Meso American and Caribbean Sea Regional Hydrographic Commission, in order to show its application and advantages. For this region it is proposed to generate a regular grid scheme with cell sizes and compilation scales (1:K) for Overview, General and Coastal navigational purposes of 24° × 24°, 6° × 6° and 1.5° × 1.5° and 1:3,000, 1:700 and 1:180 respectively, which allows to eliminate irregularities between the ENCs. This proposal contributes to the safety of maritime activities, seeking to enhance the quality of the ENC products in this region and increase trust to Electronic Chart Display and Information System users through enhanced visualization and seamless transition between ENCs of the same compilation scale. Additional serves as input for the modernization of the ENC schemes in the different Regional Hydrographic Commissions of the International Hydrographic Organization.

AIS aided marine radar target tracking in a detection occluded environment

Radar signal occlusion due to islands and large ships occurs frequently in maritime environments, degrading the performance of marine radar target detection and tracking. In order to address the common track breakages and tracking inaccuracies during occlusion, both prior environment knowledge from electronic navigation chart (ENC) and information from automatic identification systems (AIS) are exploited. An AIS-aided integrated probabilistic data association (A-IPDA) algorithm is proposed for maritime target tracking in an occluded environment. It recursively identifies target occlusion based on environmental knowledge and applies a tailored track existence probability transition matrix for track existence estimation during occlusion, meanwhile rich AIS information is exploited to maintain target tracking performance. Experiments based on both simulated data and real data show that A-IPDA has the ability to counter long period target occlusion in complex maritime environments, where track continuity and tracking accuracy can be well maintained.

Chart features, data quality, and scale in cartographic sounding selection from composite bathymetric data

ABSTRACT Cartographic sounding selection is a constraint-based bathymetric generalization process for identifying navigationally relevant soundings for nautical chart display. Electronic Navigational Charts (ENCs) are the premier maritime navigation medium and are produced according to international standards and distributed around the world. Cartographic generalization for ENCs is a major bottleneck in the chart creation and update process, where high volumes of data collected from constantly changing seafloor topographies require tedious examination. Moreover, these data are provided by multiple sources from various collection platforms at different levels of quality, further complicating the generalization process. Therefore, in this work, a comprehensive sounding selection algorithm is presented that focuses on safe navigation, leveraging both the Digital Surface Model (DSM) of multi-source bathymetry and the cartographic portrayal of the ENC. A taxonomy and hierarchy of soundings found on ENCs are defined and methods to identify these soundings are employed. Furthermore, the significant impact of depth contour generalization on sounding selection distribution is explored. Incorporating additional ENC bathymetric features (rocks, wrecks, and obstructions) affecting sounding distribution, calculating metrics from current chart products, and introducing procedures to correct cartographic constraint violations ensures a shoal-bias and mariner-readable output. This results in a selection that is near navigationally ready and complementary to the specific waterways of the area, contributing to the complete automation of the ENC creation and update process for safer maritime navigation.

Multi-functional and Practical Adaptive Collision Avoidance Decision-making System for Autonomous Ships

In the current landscape, autonomous navigation systems face challenges due to incomplete functionality and low integration. They also lack a comprehensive, real-time, and accurate navigation risk assessment, while operating independently from one another. To address these issues, a multi-functional and practical adaptive collision avoidance decision-making system for autonomous ships is developed in this paper. The system primarily relies on the electronic navigational chart (ENC) to effectively display the ship’s navigation situation. It establishes a collision avoidance decision-making model centered around the own ship, offering collision risk analysis, avoidance methods, and optimal timing to ensure safe navigation. The system efficiently integrates and processes multimodal maritime data from various devices, utilizing ontology-based approaches for comprehensive navigation situation understanding, which integration provides invaluable support for intelligent decision-making processes. With a user-friendly interface, excellent portability, and cross-platform interoperability, this system has undergone collaborative efforts and joint debugging with China Shipbuilding Navigation Technology Co., Ltd. during the project’s first and second phases. Notably, the system has been successfully implemented on the “High-performance Integrated Bridge System” platform of China Shipbuilding Navigation, showcasing its potential for advancement from principle prototype development to actual equipment application. By offering accurate collision avoidance decision support, this system significantly contributes to enhancing the safety of ship navigation.

Towards Automated Nautical Chart Compilation and Verification of Output Topology and Safety

Abstract. The compilation of Electronic Navigational Charts (ENCs) requires significant amount of time, labor-intensive efforts, and cost. Despite the advancements in technology and the various research efforts, generalization tasks are still performed manually or semi-manually with expected human errors. The dramatic increase in the amount of data that is collected by modern acquisition systems, in addition to the increasing timeline expected by the end-users, are constantly driving Hydrographic Offices (HOs) toward the investigation and adoption of more advanced and effective ways for automating the generalization tasks to speed up the process, minimize the cost, and improve productivity. Full automation of the nautical chart compilation process has been unreachable due to the strict nautical cartographic constraints (and particularly those of safety and topology) that pose a challenge for most of the available generalization tools, while it remains questionable whether automation can replace human thought processes. In this paper, we discuss a research effort for an Automated Nautical-chart Generalization (ANG) model in the Esri environment. The ANG model builds upon the nautical chart generalization guidelines and practice and utilizes available tools in the Esri environment to perform the generalization of selected ENC features to the target scale. Safety constraints in the marine domain is of utmost importance, however, since most of the readily available tools do not respect safety, the main goal of this effort has been an output with no topological violations. In the current phase of the project, we evaluate safety of soundings and contour for user fixing and while the validation of bathymetry is a well-researched topic, there was the need for an automated process to identify the sections of the generalized contours that have been displaced toward the shallow water side Therefore, this work also presents a safety validation tool that detects the contours’ safety violations in the output. The tool is composed of three main stages that run individually after the ANG model is complete with the aim to highlight the safety violations for fixing by cartographers.

Cartographic support issues in the Arctic Ocean studying and bathymetric investigation objectives in the Russian Arctic

The current state and issues of the bathymetric investigations of the Arctic Ocean are examined in the study. The main sources of bathymetric data in the Central Arctic region and Arctic seas are characterized. The main possibilities to solve these issues in order to improve the efficiency of oncoming bathymetric investigation in the Russian Arctic sector for solving the urgent practical and scientific tasks of the Russian Federation in the Arctic region are discussed. The problem of hydrographic investigation and marine cartography of the new high latitude routes in the Northern Sea Route and bathymetric investigations of the South-Eastern part of Gakkel Ridge which are important for the Russian extended continental shelf submission is covered as one of the main issues. The importance of a new hydrographic investigation at the high latitude routes in the East Siberian Sea in order to provide the possibility of year-round navigation for the large-tonnage Arc7‑class icebreaking liquefied natural gas carriers is especially emphasized. The questions of geoformation and ice satellite support for efficient navigation along the Northern Sea Route are considered. It is concluded that the poor hydrographic knowledge of the new high latitude route in the East Siberian Sea and the lack of electronic navigation charts will prevent the possibility of establishing the year-round navigation for Arc7‑class icebreaking liquefied natural gas carriers during the coming several years. It is stated that hydrographic investigations carried out on the sections of the Northern Sea Route must adhere to the requirements of the International Hydrographic Organization. The urgency of developing the state integrated bathymetric database for the Arctic Ocean including the arctic seas data along with the necessity of providing all Russian bathymetric data acquired in the Arctic region to the assigned national center is discussed. The FKU 280 ZKP VMF is proposed as such national center. The importance of bathymetric maps of the Arctic Ocean is noted. The main role of creating the electronic bathymetric maps using modern technology and analytical geomorphological mapping on the basis of the system-oriented morphological approach in Earth science is emphasised.

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.