Electronic Navigational Chart Research Articles

A semi-empirical scheme for bathymetric mapping in shallow water by ICESat-2 and Sentinel-2: A case study in the South China Sea

To derive shallow water bathymetry for coastal areas, a common approach is to deploy a scanning airborne bathymetric light detection and ranging (LiDAR) system or a shipborne echosounder for ground surveys. However, recent advancements in satellite remote sensing, including the Ice, Cloud and land Elevation Satellite-2 (ICESat-2) offer new tools for generating satellite derived bathymetry (SDB). The key payload onboard ICESat-2 is the Advanced Topographic Laser Altimeter System (ATLAS), a micro-pulse, photon-counting LiDAR system, simultaneously emitting six separate 532 nm beams at 10 kHz pulse rate. However, despite its high resolution, the major limitation for bathymetry is that ICESat-2 only provides along-track height profiles, leaving observation gaps between the parallel ground tracks. Merging ICESat-2 observations with optical multispectral imagery, as demonstrated herein, provides an effective solution for deriving a full scene of water depth in light of the spectral attenuation behavior.This study aims to combine ICESat-2 and Sentinel-2 optical data to derive shallow water bathymetry (depth <20 m) at six islands and reefs in the South China Sea. ICESat-2 ATL03 point clouds of georeferenced photons are first filtered to determine the seafloor elevation along the ground track. Results indicate a root-mean-square error (RMSE) of 0.26–0.61 m as compared with independent observations from an airborne LiDAR campaign. Next, three semi-empirical functions, namely the Modified Linear/Polynomial/Exponential Ratio Models with its kernel formed by the log ratio between Sentinel-2′s green and blue bands, are used to fit the spectral data with ICESat-2 height profiles. After water depth mapping using the trained model, independent ICESat-2 point clouds are used to validate the Sentinel-2 derived bathymetry. The RMSE values of the three models using the weighted average of multiple images for these six islands are within 0.50–0.90 m in 0–15 m deep. We also demonstrate that a synthesis of satellite laser altimetry and optical remote sensing can produce SDB results that potentially meet the requirement of category C in Zones of Confidence (ZOC) of the Electronic Navigational Chart (ENC) in 0–8 m deep. It is foreseen that ICESat-2 will be a helpful tool for mapping coastal and shallow waters around the world especially where bathymetric data are unavailable.

Determination of the Waterway Parameters as a Component of Safety Management System

This article presents the use of a computer application codenamed “NEPTUN” to ascertain the waterway parameters of the modernised Świnoujście–Szczecin waterway. The designed program calculates the individual risks in selected sections of the fairway depending on the input data, including the parameters of the ship, available water area, and positioning methods. The collected data used for analyses in individual modules are stored in a SQL server of shared access. Vector electronic navigation charts of S-57 standard specification are used as the cartographic background. The width of the waterway is calculated by means of the method developed on the basis of the modified PIANC guidelines. The main goal of the research is to prove and demonstrate that the designed software would directly increase the navigation safety level of the Świnoujście–Szczecin fairway and indicate the optimal positioning methods in various navigation circumstances.

Methodology for the Correction of the Spatial Orientation Angles of the Unmanned Aerial Vehicle Using Real Time GNSS, a Shoreline Image and an Electronic Navigational Chart

Undoubtedly, Low-Altitude Unmanned Aerial Vehicles (UAVs) are becoming more common in marine applications. Equipped with a Global Navigation Satellite System (GNSS) Real-Time Kinematic (RTK) receiver for highly accurate positioning, they perform camera and Light Detection and Ranging (LiDAR) measurements. Unfortunately, these measurements may still be subject to large errors-mainly due to the inaccuracy of measurement of the optical axis of the camera or LiDAR sensor. Usually, UAVs use a small and light Inertial Navigation System (INS) with an angle measurement error of up to 0.5∘ (RMSE). The methodology for spatial orientation angle correction presented in the article allows the reduction of this error even to the level of 0.01∘ (RMSE). It can be successfully used in coastal and port waters. To determine the corrections, only the Electronic Navigational Chart (ENC) and an image of the coastline are needed.

Grounding-aware RRT⁎ for Path Planning and Safe Navigation of Marine Crafts in Confined Waters

The paper presents a path planning algorithm based on RRT* that addresses the risk of grounding during evasive manoeuvres to avoid collision. The planner achieves this objective by integrating a collective navigation experience with the systematic use of water depth information from the electronic navigational chart. Multivariate kernel density estimation is applied to historical AIS data to generate a probabilistic model describing seafarer's best practices while sailing in confined waters. This knowledge is then encoded into the RRT* cost function to penalize path deviations that would lead own ship to sail in shallow waters. Depth contours satisfying the own ship draught define the actual navigable area, and triangulation of this non-convex region is adopted to enable uniform sampling. This ensures the optimal path deviation.

Generalization of Soundings across Scales: From DTM to Harbour and Approach Nautical Charts

This paper presents an integrated digital methodology for the generalization of soundings. The input for the sounding generalization procedure is a high resolution Digital Terrain Model (DTM) and the output is a sounding data set appropriate for portrayal on harbour and approach Electronic Navigational Charts (ENCs). The sounding generalization procedure follows the “ladder approach” that is a requisite for the portrayal of soundings on nautical charts, i.e., any sounding portrayed on a smaller scale chart should also be depicted on larger scale charts. A rhomboidal fishnet is used as a supportive reference structure based on the cartographic guidance for soundings to display a rhombus pattern on nautical charts. The rhomboidal fishnet cell size is defined by the depth range and the compilation scale of the charted area. Generalization is based on a number of rules and constraints extracted from International Hydrographic Organization (IHO) standards, hydrographic offices’ best practices and the cartographic literature. The sounding generalization procedure can be implemented using basic geoprocessing functions available in the most commonly used Geographic Information System (GIS) environments. A case study was performed in the New York Lower Bay area based on a high resolution National Oceanic and Atmospheric Administration (NOAA) DTM. The method successfully produced generalized soundings for a number of Harbour and Approach nautical charts at 10 K, 20 K, 40 K and 80 K scales.

Assessment of ship position estimation accuracy based on radar navigation mark echoes identified in an Electronic Navigational Chart

This article presents research on assessing the accuracy of ship position determination based on observations of radar echoes of navigation marks identified in an Electronic Navigational Chart (ENC). The accuracy analysis of the simulated radar positioning in relation to navigation marks the validity of the research. Position accuracy on the approach fairways was better than 6.5 m (RMS). A specially prepared measuring system made it possible to conduct tests based on radar images. In subsequent stages of the research, the association of extracted characteristic radar echoes with navigation marks found in an ENC was made. Then, in order to eliminate significant values of measurement errors and erroneous identification of navigation marks, geodetic adjustment was applied. The obtained position accuracy equal to 34.1 m (RMS) provides a premise to state that the method can be adopted for autonomous navigation systems which are alternatives to Global Navigation Satellite System (GNSS).

Paperless ship navigation: cyber security weaknesses

Maritime transportation is backbone of globalized trade and the manufacturing supply chain as nowadays more than four fifths of world merchandise trade by volume is carried by ships. Safe navigation of ships of today depends heavily on cyber-physical systems, of which the central is the Electronic Chart Display and Information System (ECDIS). The paperless ship navigation is allowed when the type approved ECDIS with official electronic navigation charts acts as an independent backup for the primary system. In this paper, we present an analysis of cyber security weaknesses of the paperless ship navigation that relies on two internetworked ECDIS workstations in the backup arrangement. The method of analysis is based on cyber security testing of the ECDIS workstations with an industry vulnerability scanner tool. The detected vulnerabilities are analysed in the context of ECDIS backup arrangement and safeguards implemented on board the paperless ship. The obtained results suggest that the critical cyber threat vectors result from uncontrolled internetworking of unmaintained ECDIS workstations with identical hardware and software configurations.

Hydrographic data inspection and disaster monitoring using shipborne radar small range images with electronic navigation chart.

Shipborne radars cannot only enable navigation and collision avoidance but also play an important role in the fields of hydrographic data inspection and disaster monitoring. In this paper, target extraction methods for oil films, ships and coastlines from original shipborne radar images are proposed. First, the shipborne radar video images are acquired by a signal acquisition card. Second, based on remote sensing image processing technology, the radar images are preprocessed, and the contours of the targets are extracted. Then, the targets identified in the radar images are integrated into an electronic navigation chart (ENC) by a geographic information system. The experiments show that the proposed target segmentation methods of shipborne radar images are effective. Using the geometric feature information of the targets identified in the shipborne radar images, information matching between radar images and ENC can be realized for hydrographic data inspection and disaster monitoring.

Gross Benefit Estimates From Reductions In Allisions, Collisions And Groundings Due To Electronic Navigational Charts

Gross Benefit Estimates From Reductions In Allisions, Collisions And Groundings Due To Electronic Navigational Charts

선박용 전자해도를 위한 해양 안전 정보 심벌 개선

해도의 심벌은 종이해도 심벌 표준인 INT1을 사용하며 이를 기반으로 제작된 전자 장비를 위한 심벌 표준 S-52를 사용해 왔다. 오래 사용해왔던 S-52의 보완과 정보의 다양한 표현을 위해 국제수로기구에서는 새로운 수로교환 표준인 S-100을 만들었으며 이를 기반으로 차세대 전자해도를 위한 연구가 진행되고 있다. 본 연구는 한국형 e-Navigation 프로젝트의 일환으로 선박용 전자해도에 표시해야 하는 해양 안전정보인 해양 보호 구역, 해양 라디오 서비스, 항해 경고, 해양 관제 시스템, 선저여유수심관리의 심벌개선 연구를 진행한 결과이다. 심벌 용례 및 표준을 분석하고 분석된 정보를 바탕으로 새로운 심벌 제작 및 디자인 개선사항을 파악하여 적용하였다. 또한 심벌 표현에 발생하는 중첩 또는 중복 이슈를 도출하고 향후 개발에 도움이 될 수 있는 대안을 제시하였다.

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New approaches to the information support of navigators are considered in the paper. They can positively influence the increase in the level of providing the modern navigators with the navigation information necessary for making decisions that make it possible to safely perform maneuvers when passing navigational hydraulic structures on inland waterways using 3D electronic navigational charts. As such approaches, a number of constructive proposals for the following methods modernization have been proposed: controlling the vessel in course, controlling the vessel in speed, controlling the velocity vector of the vessel, as well as controlling the bow and stern ends of the vessel. When navigating a vessel in course, a sequence of actions when the vessel is turning is disclosed. When considering the control of a vessel in speed, an example of displaying information on a change in the navigation situation with a change in the water level, which is important in ensuring the safety of navigation, is considered. When considering the control of the ship’s velocity vector using the 3D image of the Bagaevsky waterworks as an example, the possibility of performing a visual assessment of the spatial dimensions of objects and ships when implementing the method is emphasized. In addition, the fragments of 3D electronic navigational cartography those display the maneuvers of vessels entering a double-lane lock, showing the implementation of controlling the bow and stern ends of the vessel are presented. In the proposed study, based on the application of elements of situational analysis and methods for assessing the navigation situation by the skipper, when performing maneuvers, the recommendations that will improve the navigation safety through the use of standard electronic navigational charts and the latest 3D navigational charts are suggested.

Optimal Lowest Astronomical Tide Estimation Using Maximum Likelihood Estimator with Multiple Ocean Models Hybridization

Developing an accurate Lowest Astronomical Tide (LAT) in a continuous form is essential for many maritime applications as it can be employed to develop an accurate continuous vertical control datum for hydrographic surveys applications and to produce accurate dynamic electronic navigation charts for safe maritime navigation by mariners. The LAT can be developed in a continuous (surface) using an estimated LAT surface model from the hydrodynamic ocean model along with coastal discrete LAT point values derived from tide gauges data sets to provide the corrected LAT surface model. In this paper, an accurate LAT surface model was developed for the Red Sea case study using a Maximum Likelihood Estimator (MLE) with multiple hydrodynamic ocean models hybridization, namely, WebTide, FES2014, DTU10, and EOT11a models. It was found that the developed optimal hybrid LAT model using MLE with multiple hydrodynamic ocean models hybridization ranges from 0.1 m to 1.63 m, associated with about 2.4 cm of uncertainty at a 95% confidence level in the Red Sea case study area. To validate the accuracy of the developed model, the comparison was made between the optimal hybrid LAT model developed from multiple hydrodynamic ocean models hybridization using the MLE method with the individual LAT models estimated from individual WebTide, FES2014, DTU10, or EOT11a ocean models based on the associated uncertainties estimated at a 95% confidence level. It was found that the optimal hybrid LAT model accuracy is superior to the individual LAT models estimated from individual ocean models with an improvement of about 50% in average, based on the estimated uncertainties. The importance of developing optimal LAT surface model using the MLE method with multiple hydrodynamic ocean models hybridization in this paper with few centimeters level of uncertainty can lead to accurate continuous vertical datum estimation that is essential for many maritime applications.

Electronic Navigational Charts: International Standards and Map Projections

Electronic navigational charts (ENCs) are geospatial databases, compiled for the operational use of Electronic Chart Display and Information systems (ECDIS) according to strict technical specifications of the International Hydrographic Organization (IHO). ECDIS is a GIS system designed for marine navigation according to the relevant standards of the International Maritime Organization (IMO). The international standards for ENCs and ECDIS, issued by the IHO and IMO, cover many aspects of the portrayal of ENCs in ECDIS but do not specify or recommend map projections. Consequently, in some cases, the unjustified employment of map projections by the manufacturers has caused certain functional drawbacks and inadequacies. This article reviews, evaluates and supplements the results of earlier studies on the selection of map projections for the depiction of ENCs in ECDIS and proposes a reasonable set of suitable projections with pertinent selection/implementation rules. These proposals took into consideration that ECDIS users (navigators) are not GIS experts or professional cartographers and consequently, the proposed election/implementation rules have to be simple and straightforward.

A review of universal hydrographic data model

The Universal Hydrographic Data Model is a new generation of marine geographic information data model, referred to as S-100 standard. In addition to supporting Electronic Navigational Charts (ENC) production, S-100 can be used as a Geographic Information System standard to model all maritime objects. Therefore, it is necessary to carry out a comprehensive study on S-100. In this review, we begin with a succinct overview of the history and development of S-100. Then we discussed the problems of S-100 and the corresponding solutions. Finally, some research directions of S-100 are proposed to provide reference for future research and application.

A causative analysis on ECDIS-related grounding accidents

ABSTRACT This study introduces an assessment concerning the use of Electronic Chart Display and Information System (ECDIS) in the safe navigation of vessels by considering the case studies whether the device played a role in grounding accidents. A total 80 investigation reports of grounding accidents from 2008 to 2018 were analysed. In 22 cases, one or more findings related to ECDIS and Electronic Navigational Charts (ENC) were identified. Twenty two accidents related to ECDIS or ENCs were re-analysed with 4M Overturned Pyramid (MOP) model to determine the characteristics and causes of accidents. Causative factors that related ECDIS in the cases have been listed and explained. Results indicate that ECDIS-related procedures and lack of training have led to incorrect settings of the device, especially alarm settings. The recommendations have been arranged that ECDIS devices, which offer much considerable information for the safe navigation of ships, are able to work more efficiently.

Methodology for Processing of 3D Multibeam Sonar Big Data for Comparative Navigation

Autonomous navigation is an important task for unmanned vehicles operating both on the surface and underwater. A sophisticated solution for autonomous non-global navigational satellite system navigation is comparative (terrain reference) navigation. We present a method for fast processing of 3D multibeam sonar data to make depth area comparable with depth areas from bathymetric electronic navigational charts as source maps during comparative navigation. Recording the bottom of a channel, river, or lake with a 3D multibeam sonar data produces a large number of measuring points. A big dataset from 3D multibeam sonar is reduced in steps in almost real time. Usually, the whole data set from the results of a multibeam echo sounder results are processed. In this work, new methodology for processing of 3D multibeam sonar big data is proposed. This new method is based on the stepwise processing of the dataset with 3D models and isoline maps generation. For faster products generation we used the optimum dataset method which has been modified for the purposes of bathymetric data processing. The approach enables detailed examination of the bottom of bodies of water and makes it possible to capture major changes. In addition, the method can detect objects on the bottom, which should be eliminated during the construction of the 3D model. We create and combine partial 3D models based on reduced sets to inspect the bottom of water reservoirs in detail. Analyses were conducted for original and reduced datasets. For both cases, 3D models were generated in variants with and without overlays between them. Tests show, that models generated from reduced dataset are more useful, due to the fact, that there are significant elements of the measured area that become much more visible, and they can be used in comparative navigation. In fragmentary processing of the data, the aspect of present or lack of the overlay between generated models did not relevantly influence the accuracy of its height, however, the time of models generation was shorter for variants without overlay.

A Method of Path Planning on Safe Depth for Unmanned Surface Vehicles Based on Hydrodynamic Analysis

The depth of water is of great significance to the safe navigation of unmanned surface vehicles (USV)in shallow waters, such as islands and reefs. How to consider the influence of depth on the safety of USV navigation and path planning is relatively rare. Under the condition of ocean disturbance, the hydrodynamic characteristics of unmanned surface vehicles will affect its draft and depth safety. In this paper, the hydrodynamic model of unmanned surface vehicles is analyzed, and a water depth risk level A* algorithm (WDRLA*) is proposed. According to the depth point of the electronic navigation chart (ENC), the gridding depth can be obtained by spline function interpolation. The WDRLA* algorithm is applied to plan the path, which takes hydrodynamic characteristics and navigation errors into account. It is compared with the traditional A* shortest path and safest path. The simulation results show that the WDRLA* algorithm can reduce the depth hazard of the shortest path and ensure the safety of navigation.

Adding value to ENCs: Land features

Abstract. In the 1990’s, the International Maritime Organization (IMO) adopted the International Hydrographic Office’s (IHO) S-57 performance standards for Electronic Navigation Charts (ENC), which enforce standardized content, structure, and format. The IMO also revised its Safety of Life at Sea (SOLAS) chapter V regulations to require Electronic Chart Display and Information Systems (ECDIS) onboard certain SOLAS class vessels, starting from 2018. These systems allow for navigating with ENC data, which has several advantages over paper charts; however, many mariners still prefer traditional paper or raster charts. Through the feedback of key stakeholders such as local pilot associations, it has become apparent that the preference for raster or paper charts is due to the inclusion of non-critical S-57 land features. These S-57 land features, which are typically not added to ENC products, such as roads and elevation contours, can supplement navigational positioning systems by providing visual references, particularly when other landmarks (e.g., spot elevations on major topographic features) are not present on the ENC. Moreover, charting roads on ENC products can be useful for locating water access points. This paper discusses the addition of roads and land elevation contours to NOAA’s re-schemed ENC suite in an effort to supplement currently charted marine features and land features crossing over water. General cartographic guidelines have also been developed for the representation of these features through ENC scales (i.e., usage bands 3 to 5). Additionally, this paper includes a discussion on the benefits and challenges of incorporating publicly available land transportation data versus traditional sources on ENC products.

History of Japan’s chart production in 150 years

Abstract. In 1853, the United States sent Commodore Perry with 4 warships to Japan, and urged opening the country to the world. Since then, Japan had entered into treaties of commerce with Western nations, and opened the ports for these nations. However, Japan was in military disadvantage with other nations having charting knowledge of Japan and it surroundings. As a result, a decision was made to establish chart production capabilities in Japan in the view of the national security. Soon after, the Japanese chief military commander opened two naval officer training facilities in Nagasaki (1855) and Tsukiji (1857). Surveying was also one of the subjects of taught at these training organizations.Japan Hydrographic Department (JHD, currently Japan Hydrographic &amp;amp; Oceanographic Department) was established as the organization for chart production under the navy in 1871, and graduates of the above naval officer training facilities led the activities of JHD in its early stage. The first Chief Hydrographer YANAGI Narayoshi was one of them. JHD published its first navigational chart “KAMAISHI BAY of RIKUCHU” in 1872, the next year of its establishment, and expanded its chart series after that.As Japan experienced several wars and expanded its national jurisdiction by 1945, JHD expanded its chart series. Most of these charts were open to the merchant ships, but some of them were not open to public as military secrets at that time. Furthermore, JHD, as one of the organizations under the navy, made aeronautical charts for naval airplanes. These charts have been stored in archives, but some were lost in fires. Not all of charts ever published by JHD exist now. The existing charts published by 1945 are kept in the Hydrographic &amp;amp; Oceanographic Museum.After World War II, JHD was restructured as one of the organizations of Japan Coast Guard under the Ministry of Transport (currently the Ministry of Land, Infrastructure and Transport). The chart production of Japan in post war days has received big influences by the economic situation of Japan and the world, frameworks of international societies and developments of the technologies.In the viewpoint of the economic situation, the number of chart publication increased due to the large number of the constructions of domestic harbours in the periods of the post war reconstruction and the following high economic growth of Japan, but it has decreased little by little since 1970’s by the influences of such as depressions of domestic economy, and decrease of ships registered in Japan and Japanese mariners. On the other hand, JHOD has published navigational charts written only in English in recent years for foreign mariners which number increases like supplementing a decrease of Japanese mariners. Moreover, JHOD has published basic maps of the sea as basic material of use, development, environmental preservation and the natural disaster prevention etc. of the ocean.In the viewpoint of the frameworks of the international societies, JHOD has published fishery charts which show the fishery areas on the agreements between neighbouring countries, and also writes the straight baselines and limits of the territorial sea on the navigational charts according to United Nations Convention on the Law of the Sea.In the viewpoint of the developments of the technologies, innovations of positioning technology and improvement of the computer ability influenced largely in chart production. JHOD used to publish Decca charts and Loran charts in the age of radio navigation. Because satellite navigation became common in recent years, the difference between WGS84 and Tokyo-datum (nearly 500 m) was put in questions. Corresponding to it, JHOD temporarily published some Tokyo-datum charts on which latitude and longitude lines based on WGS84 in green were added, and since 2000, JHOD has published navigational charts based on WGS84 and no more on Tokyo-datum. Furthermore, with the growth of computer ability, JHOD has shifted its chart compilation from full manually to by using computer assisted partly, and in 1996, JHOD established chart compilation process under fully computer assisted. In addition, JHOD published the first electronic navigational chart (ENC) in the world in 1995.JHOD as the responsible organization of Japan for chart production will continue to produce charts in the future adjusting to the environment that surrounds charts and navigations.

Raster charting products in an ENC-first era

Abstract. Nautical charts are an essential tool for marine navigation. Despite the introduction of global positioning systems (GPS) and electronic navigational tools that present navigation data in a vector format on a display, paper charts are still the preferred choice for many mariners. Interestingly, since the introduction of Electronic Navigation Charts (ENCs) more than thirty years ago, the size of commercial vessels has increased more than four-fold, modern navigational systems have become more sophisticated, and recreational boaters have joined professional mariners in using electronic chart displays. Marine and coastal users of all types are expecting higher resolution and more precision in location of the charted features, and shorter update times for data sources to be published on the chart. With NOAA’s new plan to “standardized, consistent gridded framework” that is optimized for digital displays, it leaves the future of paper charts in question. In order to support a raster-based maintenance system, it is now possible to translate encoding attributes of vector objects into standardized chart symbols and labels. Thus, simplifying workflow processes for paper and raster chart production. This paper discusses NOAA Marine Chart Division’s raster workflow in an ENC-first production line. The paper reviews the benefits of the new desktop tools and web-services for providing chart updates in a timely manner for a broader community.