Sea Charts Research Articles

Global path planning of unmanned ship island region based on improved A* algorithm

Abstract To solve the path planning problem for unmanned boats in island and reef areas, this paper introduces an adaptive heuristic function specifically for island and reef areas based on the traditional A* algorithm, in order to effectively handle the obstacle avoidance problem. A new cost function is designed to balance the relationship between path length and safety. The sea chart is converted into a path planning map by using the grid method, and the path planning is carried out. The paper compares the performance of the new path-planning algorithm with other path-planning algorithms through experiments, and the improved A* algorithm for global path planning of unmanned boats in island and reef areas shows excellent performance in various complex environments, effectively improving the island and reef area navigation efficiency.

Qing China and Its Offshore Islands in the Long Eighteenth Century

AbstractA significant paradigm shift in the examination of China’s engagement with the maritime world has taken place over the past decade. The conventional image of the Qing dynasty in the long eighteenth century as being merely land-orientated has now become obsolete. Historians are no longer satisfied with this stereotype and have put aside the conception that the Qing only realized the importance of strategic marine governance after the First Opium War. In view of this historiographical turn, I seek to deepen our understanding of the Great Qing in relation to the sea. By focusing on a series of sea charts, alongside some relevant palace papers, from the eighteenth and early nineteenth centuries, I will argue that the Qing’s process of locating and charting those offshore islands was an essential, indicative, and demonstrative step for the central authority to project its imperial power onto the waters off the coast of China long before the arrival of Western gunboats in the age of global rivalry.

Release note for the BSCD2000 height transformation grid

A unified Chart Datum for the whole Baltic Sea is required for the use of global navigation satellite systems (GNSS) in accurate 3-D bathymetric surveying and navigation, enabling for automated shipping with increased efficiency and improved maritime safety. So far, the zero levels of nautical maps were derived from the mean sea level (MSL) of different local tide gauges. The inherent height datum differences between neighboring map sheets are a fundamental infrastructural obstacle for implementing and using new cross-border navigation services based on electronic nautical maps. The Baltic Sea Hydrographic Commission, with its Chart Datum, Water Level and Currents Working Group (CDWCWG), has therefore decided to implement a harmonized vertical reference in the Baltic Sea (BSHC18 conference, 2013; Schwabe et al., 2020) called the Baltic Sea Chart Datum 2000 (BSCD2000). The first milestone was the agreement between the Baltic Sea countries on the fundamental standards of the BSCD2000, the general features of its practical realization, and the roadmap for the transition and implementation of the new chart datum (CDWG8, 2016).

Quṭb al-Dīn al-Shīrāzī’s Textual Map of the Mediterranean Sea (1282) and Its Evident Source in a Portolan Chart

ABSTRACT In 1282, the Persian scholar, Quṭb al-Dīn al-Shīrāzī (d. 1311), included in a cosmographical work a description of a ‘Greek’ map of the Mediterranean. Rather than reproducing this map graphically, he placed a square grid over the image, listed the cells covered by the sea, and then itemised the toponyms according to their cell numbers. Once this pixelated map is created as he instructed, it is obvious that the ‘Greek’ map must have been an Italian portolan chart, featuring its unique elements: a realistic outline for the northern coast of Africa, especially the Gulf of Sirte, a simplistic rectangular form for the British Isles, a counterclockwise tilt, and a large size. With a toponymy that matches that on the oldest surviving portolan chart (the Carte Pisane, c.1270) and the next survivor (the Cortona chart), assigned to later that century, the ‘Greek’ map in Shīrāzī’s possession in 1282 seems to be the second oldest portolan chart of which we have specific knowledge. This article recounts how a Persian cosmographer disseminated a cartographic image based on the direct observations of Christian pelagic mariners. This unexpected material evidence confirms that knowledge of those earliest accurate sea charts was not confined to the Latin world, even if such information exchanges were probably rare.

Analysing topographical transformation of Bombay Islands and Bombay Fort using geospatial analysis and historical records

Mumbai is on a narrow peninsula, which lies between the Arabian Sea on the west, Thane Creek on the east and Vasai Creek on the north; consisting of two distinct regions, Mumbai City and Mumbai Suburban. The city district region or South Mumbai is also commonly referred to as the Island City, as historically this area consisted of islands separated by the sea. There were several historical fortifications dotted on these islands, such as Worli, Mahim, Sion, Sewri, Bandra and the largest of these was the Bombay Fort. The islands were combined into one landmass by man-made changes spread over a century and the ensuing land-use changes and urbanisation erased the contours of the extents of forts as well as islands. The history of the city has been a subject of interest to researchers; it is widely believed that prior to the first phase of reclamation (1711–1728 CE) there were seven islands. However, past scholarship has pointed out that the model of seven distinct islands was first introduced in a map published in 1843 CE, which retrospectively speculated the original landscape and this model has not been subjected to a scientific analysis so far (Ridings in J. Historic Geograp 59:27–39, 2018). The present study: firstly uses historical maritime cartographic records (such as sea charts, maps, birds-eye views, admiralty charts, portolan charts and pilots, made by Portuguese, French, Dutch and British) to geospatially identify and map the spatial evolution of the islands that formed the present South Bombay; secondly, traces the layout and evolution of the Bombay Fort which was the hub of power and economy of Bombay Presidency during seventeenth and eighteenth centuries and which also houses remnants of few buildings including the castle built by Portuguese.

Buoy Light Pattern Classification for Autonomous Ship Navigation Using Recurrent Neural Networks

In near coast navigation, buoys and beacons convey essential information about dangers. At night-time, selected buoys send out individual blink-sequences that are marked in sea charts. International regulations require that navigation officer on watch makes visual confirmation of objects and their type in order to navigate safely. With rapid developments of highly automated vessels, this duty needs be carried out by algorithms that detect and locate objects without human intervention. At night-time, this requires algorithms that decode blink sequences and are able to classify from this information. The paper investigates this problem and suggests an algorithm that solves the problem. Convolutional Neural Networks (CNN) with Gated Recurrent Units (GRU) are developed for classification. A dedicated architecture is suggested that includes both temporal and color decoding to obtain unique precision. We demonstrate how networks are trained on synthetically generated data, and the paper shows, on real-world data, how the suggested approach yields 100.0% accurate results on 44 real-world recordings while being robust to inaccuracy in actual blink sequences. Comparison with baseline signal processing and with a recent state-of-the-art 3D CNN model shows that the new blink-sequence classifier outperforms alternative algorithms. A showcase of the results of this work is available in this video: <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://youtu.be/KEi8qNnKV2w</uri> .

The Influence of Bathymetry on Regional Marine Geoid Modeling in Northern Europe

Although Northern Europe has been the target area in many regionwide geoid determination studies, the research has been land-focused, neglecting bathymetry information. With new projects, such as the Baltic Sea Chart Datum 2000, the attention is shifting toward the marine geoid. Hence, consideration for bathymetry has become relevant, the influence of which is studied. In the relatively shallow Baltic Sea, accounting for bathymetry-based residual terrain model reduction during gravity data processing induces marine geoid modeling differences (relative to neglecting bathymetry) mainly within 2 cm. However, the models can deviate up to 3–4 cm in some regions. Rugged Norwegian coastal areas, on the other hand, had modeling improvements around a decimeter. Considering bathymetry may thus help improve geoid modeling outcomes in future Northern Europe geoid determination projects. Besides using the conventional precise GNSS-leveling control points, the paper also demonstrates the usefulness of shipborne GNSS and airborne laser scanning-derived geoidal heights in validating geoid modeling results. A total of 70 gravimetric geoid solutions are presented, for instance, by varying the used reference global geopotential models. According to the comparisons, GOCO05c-based solutions generally perform the best, where modeling agreement with GNSS-leveling control points reached 2.9 cm (standard deviation) from a one-dimensional fit.

Shipborne GNSS-Determined Sea Surface Heights Using Geoid Model and Realistic Dynamic Topography

With an increasing demand for accurate and reliable estimates of sea surface heights (SSH) from coastal and marine applications, approaches based on GNSS positioning have become favored, to bridge the gap between tide gauge (TG) and altimetry measurements in the coastal zone, and to complement offshore altimetry data. This study developed a complete methodology for jointly deriving and validating shipborne GNSS-determined SSH, using a geoid model and realistic dynamic topography estimates. An approach that combines the properties of hydrodynamic models and TG data was developed to obtain the latter. Tide gauge data allow estimating the spatiotemporal bias of a hydrodynamic model and, thus, linking it to the used vertical datums (e.g., a novel geoid-based Baltic Sea Chart Datum 2000). However, TG data may be erroneous and represent different conditions than offshore locations. The qualities of spatiotemporal bias are, hence, used to constrain TG data errors. Furthermore, a rigid system of four GNSS antennas was used to ensure SSH accuracy. Besides eliminating the vessel’s attitude effect on measurement data, the rigid system also provides a means for internal validation, suggesting a 4.1 cm height determination accuracy in terms of standard deviation. The methodology also involves eliminating the effect of sea state conditions via a low-pass filter and empirical estimation of vessel sailing-related corrections, such as the squat effect. The different data validation (e.g., examination of residual values and intersection analyses) results, ranging from 1.8 cm to 5.5 cm in terms of standard deviation, indicate an SSH determination accuracy of around 5 cm.

Treatment of Tide Gauge Time Series and Marine GNSS Measurements for Vertical Land Motion with Relevance to the Implementation of the Baltic Sea Chart Datum 2000

Tide gauge (TG) time series and GNSS measurements have become standard datasets for various scientific and practical applications. However, the TG and geodetic networks in the Baltic Sea region are deforming due to vertical land motion (VLM), the primary cause of which is the glacial isostatic adjustment. Consequently, a correction for VLM, either obtained from a suitable VLM model or by utilizing space-geodetic techniques, must be applied to ensure compatibility of various data sources. It is common to consider the VLM rate relative to an arbitrary reference epoch, but this also yields that the resulting datasets may not be directly comparable. The common height reference, Baltic Sea Chart Datum 2000 (BSCD2000), has been initiated to facilitate the effective use of GNSS methods for accurate navigation and offshore surveying. The BSCD2000 agrees with the current national height realizations of the Baltic Sea countries. As TGs managed by national authorities are rigorously connected to the national height systems, the TG data can also be used in a common system. Hence, this contribution aims to review the treatment of TG time series for VLM and outline potential error sources for utilizing TG data relative to a common reference. Similar consideration is given for marine GNSS measurements that likewise require VLM correction for some marine applications (such as validating marine geoid models). The described principles are illustrated by analyzing and discussing numerical examples. These include investigations of TG time series and validation of shipborne GNSS determined sea surface heights. The latter employs a high-resolution geoid model and hydrodynamic model-based dynamic topography, which is linked to the height reference using VLM corrected TG data. Validation of the presented VLM corrected marine GNSS measurements yields a 1.7 cm standard deviation and −2.7 cm mean residual. The estimates are 1.9 cm and −10.2 cm, respectively, by neglecting VLM correction. The inclusion of VLM correction thus demonstrates significant improvement toward data consistency. Although the focus is on the Baltic Sea region, the principles described here are also applicable elsewhere.

Anchoring the Image of the Sea: Copying Coastlines on Manuscript Nautical Charts from the Late Middle Ages and the Early Modern Period

ABSTRACT The birth of the nautical chart in the late medieval period is seen as a watershed moment in the history of cartography. So far, however, the artisanal practices that permitted the proliferation of sea charts have remained poorly understood and little evidence has been recovered from extant charts on which to base the production history of the surviving charts. This article describes a systematic exploration of the techniques employed in the copying of coastlines on manuscript charts between the fourteenth and early seventeenth centuries. Attention is drawn to the ways different processes shaped contemporary late-medieval and early-modern understanding of the Mediterranean and what the techniques may reveal of that thinking. By reframing the charts in terms of their characteristics as drawings and placing map making in the broader context of two-dimensional graphic art, and by making use of the ever-growing corpus of high-resolution digital reproductions, we gain new insights into the chartmakers’ changing approaches to the transmission of geographical information. At the same time, a number of directions for further research are opened up.

GNSS Independent Position Fixing using Multiple Navigational Features Registration

Safe navigation at sea depends on reliable position information. The easy to use and readily available navigation satellite systems are providing round the clock position information for seafarers, but denial of these services by jamming or spoofing techniques have become frequent, and other means are needed to validate critical navigation information. This paper revisits traditional methods to estimate position and heading of a vessel and offers a framework for computerized calculation of these basic observables without the use of radio-borne external information. Using radar and sea chart information, the paper investigates the quality of navigation information based on observed location of beacons, landmarks, coastlines and buoys. The paper demonstrates convincing accuracy in both position and heading estimation.

New Results For Teaching Ship Handling Using Fast Time Simulation

Some years ago, the SAMMON software tool box was introduced for “simulation augmented manoeuvring design, monitoring &amp; conning”. It is based on the innovative “rapid advanced prediction &amp; interface technology” (RAPIT) to simulate the ships motion by fast time simulation FTS with complex dynamic math models and to display the ships track immediately in an electronic sea chart for any rudder, thruster or engine manoeuvre planned by the navigator.specifically, the SAMMON planning tool will be shown in its opportunities for achieving new knowledge for teaching of ships dynamic and training of ship handling elements. That system represents the full information from ships’ manoeuvring documentation and from additional trial results squeezed in a ship dynamic model, capable of simulating environmental effects by using the RAPIT technology. The paper introduces the variety of opportunities of the training tools by presenting use case studies, e.g. For drifting under wind and how to get simple formulas for drift speed related to wind speed. Additionally, two complex manoeuvring strategies for a port arrival scenario will be compared for a ship with azimuth propeller to find out potential alternatives with less fuel consumptions and emissions.

Detecting Water Depth from Remotely Sensed Imagery Based on ELM and GA-ELM

The shallow seawater depth inversion based on remote sensing technology is important for water depth detection, which is of considerable significance to marine engineering, shipping, and marine military security. In this study, we took the Taiping Island and its adjacent waters in the South China Sea as a test bed and developed a water depth inversion model on the basis of extreme learning machine (ELM) and extreme learning machine optimized by genetic algorithm (GA-ELM). In GA-ELM, the input weights and the hidden layer biases were optimized by genetic algorithm. The two models allowed the evaluation of nonlinear relationships between the reflectance of high-resolution imagery from WorldView-2 and actual water depth obtained from the S-57 sea chart. The eight bands of the high-resolution image and the actual water depth were used as the input layer and the output layer, and the sigmoid function was introduced as activation function. Finally, the model accuracy was evaluated by using mean relative error (MRE), root mean square error (RMSE), mean absolute error (MAE), coefficient of determination (R2), and the regression analysis between the retrieved water depth and the actual data. The simulation results showed that the two models had better stability than the second-order polynomial regression, BP neural network, and RBF neural network. Furthermore, GA-ELM had a more compact network structure and better generalization ability than ELM. Thus, we concluded that GA-ELM had higher precision and could achieve a better inversion result in the experimental area.

A Trajectory Classification Model Using Grammar Parsing

Trajectory classification is a hot topic in the field of spatiotemporal data mining. Existing models exert spatial or temporal computation on trajectory data, which require huge efforts and are often time consuming and lack of efficiency. This article proposes a model to classify unknown ship trajectories through a syntax recognition approach. By using the background semantic information in the rasterized sea chart, the model transforms the ship trajectories into symbolic sentences containing both spatiotemporal and semantic information, and reduces their scale. The class feature is expressed as a context-free grammar and the data classification is implemented through syntax parsing. The parsing requires less computation and is more efficient. Experiments are carried out to verify the model’s practicability, and the results show that it is valid and effective.

Harnessing Publicly Available Information with Data Science to Extract the Operational Profile of a Vessel

The optimal design of an efficient and cost-effective vessel requires extensive knowledge about its intended operation. However, this information is not always available or accessible for a ship designer/yard. This often results in a vessel which is less well suited for the job than it should be. The vessel is over specified for the required task and as a result more expensive than it could be for the client to buy and operate. A platform was developed which can extract the entire operational profile of a trailing suction hopper dredger with as little information as possible. The information used consists of publicly available data, such as that of the automatic identification system, weather information and sea charts. The platform uses machine learning algorithms to determine the vessel task, time spent in the task and the vessel uptime. Combining these results with additional knowledge of dredgers and their drive systems allows for an estimation of both the dredger production and the power and fuel consumption. The paper discusses the methods used in the platform to extract the operational profile from the publicly available data and how this results in a power and fuel consumption estimation. The results of the platform will be validated with information available from two trailing suction hopper dredgers.

Fighting the Great War at the Adriatic Sea: charts by Hydrographic Office of the Austro-Hungarian Navy

ABSTRACTThe Hydrographic Office of the Austro-Hungarian Navy, headquartered in Pola since 1869, was in charge of conducting maritime surveys and producing all sea charts until 1918. At the beginning of the 20th century, the Austro-Hungarian Navy was still using the revised charts that were based on the hydrographic survey conducted by Tobias von Oesterreicher in 1866–1870. In order to meet the new requirements necessitated by the introduction of dreadnought battleships and submarines, at the dawn of WWI Austro-Hungary started a new hydrographic survey of the Adriatic, conducted under the command of Arthur Catinelli Edler von Obradich-Bevilacqua. The survey, which was launched in 1907 had the task of providing modern and reliable maritime charts accompanied by dense soundings, more data on the composition of the seafloor, as well as some adjustments in the process of construction of the charts. Charts that were based on this survey had a crucial role in all WWI naval operations in the Adriatic Sea.

Charting a Course for Success: The Importance of an Initial Case Plan

When planning to set sail to a new foreign port, any seasoned sailor will carefully review the sea charts and plot out the best course to arrive quickly and safely at the destination. Indeed, only a fool would simply set sail without a plan, hoping for the best.

Island Identification at River Estuary Based on Toponymy (Case Study: River Estuary of Bulungan, BulunganRegency, North Kalimantan Province)

Toponymy is the scientific study of geographical names. Island Toponym represents step of island identi- fication by identifying its name and geographic position. Island Identification in toponymy was conducted through desk study and field survey. Desk study was implemented to obtain earlier description of islands physical condition, social and culture of local people. Field survey to obtain names of the islands was carried out by interviewing local people and positions were measured by using a simple GPS system then validated using nautical chart Dishidros publications 1997 and Image from Google Earth in 2013. The Survey at Bulungan Regency of East Kalimantan Province, 19 islands had been identified 7 islands which have not been listed at DEPDAGRI (Ministry of Internal Affairs) in 2004 but the other 10 islands have been named, and 9 island which is not drawn yet in sea chart published by DISHIDROS TNI-AL.

CRMgeo: A spatiotemporal extension of CIDOC-CRM

CRMgeo is a formal ontology intended to be used as a global schema for integrating spatiotemporal properties of temporal entities and persistent items. Its primary purpose is to provide a schema consistent with the CIDOC CRM to integrate geoinformation using the conceptualizations, formal definitions, encoding standards and topological relations defined by the Open Geospatial Consortium in GeoSPARQL. To build the ontology, the same ontology engineering methodology was used as in the CIDOC CRM. CRMgeo first introduced the concept of Spacetime volume that was subsequently included in the CIDOC CRM and provides a differentiation between phenomenal and declarative Spacetime volume, Place and Time-Span. Phenomenal classes derive their identity from real world phenomena like events or things and declarative classes derive their identity from human declarations like dates or coordinates. This differentiation is an essential conceptual background to link CIDOC CRM to the classes, topological relations and encodings provided by Geo-SPARQL and thus allowing spatiotemporal analysis offered by geoinformation systems based on the semantic distinctions of the CIDOC CRM. CRMgeo introduces the classes and relations necessary to model the spatiotemporal properties of real world phenomena and their topological and semantic relations to spatiotemporal information about these phenomena that was derived from historic sources, maps, observations or measurements. It is able to model the full chain of approximating and finding again a phenomenal place, like the actual site of a ship wreck, by a declarative place, like a mark on a sea chart.

DISASTER PREVENTION COASTAL MAP PRODUCTION BY MMS &amp; C3D

Abstract. In March 2011, Eastern Japan suffered serious damage of Tsunami caused by a massive earthquake. In 2012, Ministry of Land, Infrastructure and Transport published “Guideline of setting assumed areas of inundation by Tsunami” to establish the conditions of topography data used for simulation of Tsunami. In this guideline, the elevation data prepared by Geographical Survey Institute of Japan and 2m/5m/10m mesh data of NSDI are adopted for land area, while 500m mesh data of Hydrographic and Oceanographic Department of Japan Coast Guard and sea charts are adopted for water area. These data, however, do not have continuity between land area and water area. Therefore, in order to study the possibility of providing information for coastal disaster prevention, we have developed an efficient method to acquire continuous topography over land and water including tidal zone. Land area data are collected by Mobile Mapping System (MMS) and water area depth data are collected by interferometry echo sounder (C3D), and both data are simultaneously acquired on a same boat. Elaborate point cloud data of 1m or smaller are expected to be used for realistic simulation of Tsunami waves going upstream around shoreline. Tests were made in Tokyo Bay (in 2014) and Osaka Bay (in 2015). The purpose the test in Osaka Bay is to make coastal map for disaster prevention as a countermeasure for predicted Nankai massive earthquake. In addition to Tsunami simulation, the continuous data covering land and marine areas are expected to be used effectively for maintenance and repair of aged port and river facilities, maintenance and investigation of dykes, and ecosystem preservation.