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

This article presents technology for the production of electronic navigational charts (ENC) in the Hydrographie Institute of the Republic of Croatia (HIRC); current conditions of producing ENC cells and comparison with international experiences. ENC database together with GPS and onboard sensors make up -electronic chart display and information system (ECDIS) navigational GIS. The purpose of ENC and ECDIS is improvement of navigational safety and protection of marine environment. HIRC is participant of the international pilot project "North Adriatic virtual regional electronic nautical chart" (VRENC), deals with standardization in production and distribution of ENCs covering the area of the North Adriatic Sea. In international relations HIRC has a rather satisfying ENC production

It is seen that high technology and its products work to meet every stage and need of human life and navigational safety in the maritime sector. Electronic systems have been developed and are used today as a result of the search for alternatives to the well-known and approved classical methods used in safe navigation on the world's seas. Electronic systems are susceptible and more accurate than classical methods and significantly benefit maritime transport. Bridge electronic systems and infrastructures supporting its components also work with advanced technology products. In this context, electronic navigational charts - ENC, Electronic Chart Display Information systems - ECDIS and Automatic Information systems - AIS are undoubtedly the best examples. These and similar bridge and auxiliary devices ensure the safety of navigation on both national and international seas and oceans and cause a decrease in human error rates. This study mentions the positive effects of high-tech bridge navigation systems developed in the maritime sector on maritime transportation.

Bathymetric data quality on Electronic Navigational Charts (ENCs) is encoded with the Category Zone of Confidence (CATZOC) providing information about horizontal and vertical uncertainty, seabed coverage, and feature detection. To support safe navigation, the nautical charting community has been investigating improved methods for the inclusion of data quality on charts and the integration on Electronic Chart Display and Information Systems (ECDISs). One of the major changes is the decision to replace the problematic star symbology. Recognizing that effective visualizations result in better–informed decisions, we investigate new techniques for the visualization of bathymetric data quality on ECDIS. This is expressed through our countable textures, one with lines and one with dot–clusters, as well as two techniques for improving the data quality integration within ECDIS safety checks. Regarding the former, this paper summarizes the research effort from identifying the deficiencies of star symbology, to conceptualization, development, and evaluation of the countable textures that demonstrated the superiority of the concept compared to ideas previously discussed within the community. Regarding the latter, this paper presents the two techniques under evaluation in collaboration with maritime academies in the US that aim to facilitate the use of data quality information during the execution of the passage.

Nautical cartography competences and their effect to the realisation of a worldwide Electronic Navigational Charts database, the performance of ECDIS and the fulfilment of IMO chart carriage requirements

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.

The Zones of Confidence (ZOC) is a composite data quality indicator used in Electronic Navigational Charts. Accident reports show that failing to account for chart data quality can result in maritime accidents and loss of life. ZOC overlays are intended to help mariners in identifying potential seafloor hazards and in plotting routes safe for the vessel, but a major concern with the ZOC concept has been the utilized symbology with glyphs consisting of stars. Due to its recognized deficiencies, star-symbology has been rejected for use with the successor of ZOC, the Quality of Bathymetric Data (QoBD). This work presents a research effort toward a new QoBD representation. We define the requirements for the new coding scheme to be effective and propose two texture schemes incorporating countable elements, one consisting of lines and one of dot clusters. For comparison, we developed three alternative, color-based, coding schemes based on ideas previously expressed in the maritime community. Lastly, we present the design, dissemination, and results of an online user survey carried out to evaluate the five coding schemes. The survey results demonstrate that the proposed textures are the most preferred coding schemes among survey respondents.

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

Some issues of increasing the energy efficiency of ships by improving navigation methodsTraditional ship passing methods are mostly focused on minimizing the risk of collision without considering fuel consumption, which complicates achieving sustainable development goals in maritime transport. At the same time, rising fuel costs, tightening international environmental regulations, and the need to reduce greenhouse gas emissions highlight the importance of integrating energy efficiency principles into the navigation decision-making process. This work examines the functional capabilities of overlaying radar imagery on the ECDIS display as one of the key tools supporting energy-efficient maneuvering during ship passing. The advantages and limitations of integrating radar information with electronic navigational charts are analyzed, as well as the impact of such integration on improving navigation accuracy, reducing collision risks, and supporting sustainable fuel use. The relevance of integrating radar information with ECDIS to enhance real-time situational awareness is substantiated. It is shown that combining radar data with ECDIS significantly reduces the risks of erroneous decisions in conditions of limited visibility and high traffic density, and also provides better situational interpretation for making energy-efficient maneuvering decisions. It is determined that such integration is a key component of modern navigation decision support systems, as it allows consideration of the real situation and characteristics of target objects while accounting for safe and economically feasible courses. The implementation process of collision avoidance systems using models aimed at ensuring navigational safety is analyzed, along with revealing their potential for optimizing energy consumption in maritime transport. A conceptual model for selecting the optimal ship passing maneuver is proposed, based on the combination of safety criteria and fuel consumption minimization. Special attention is given to the use of the Open Sea Model (OSM) as a tool for forecasting and evaluating movement trajectories considering various ship interaction scenarios. Particular focus is placed on the challenges of integrating this system with modern navigation complexes, including ECDIS, Automatic Identification Systems (AIS), and radars, to ensure real-time operation.

Topography represented in the form of Digital Elevation Models (DEMs) has profound applications in hydrological modeling. DEMs can be generated from several sources including satellite products, contours, survey data, and LiDAR, each with their own merits and demerits. Where high resolution, accuracy, and spatial extent are concerned, it is often found that a DEM from one source alone is not able to represent the topography of the target area with full accuracy. Upon comparing different DEMs, it was found that most were able to successfully represent mountainous regions but failed to represent flat deltaic regions. Therefore, in this research with Bago River basin, Myanmar as a study area, a new methodology to combine multiple sources of data with different data types is developed. The inputs are: (a) a 10 m DEM, developed using contour data, point elevation data, and UTM topographic maps; (b) a 5 m Digital Surface Model (DSM) acquired by the Advanced Land Observation Satellite (ALOS); and (c) 168 sets of multiple-point elevation data representing a cross-sectional survey along the Bago River and the Bago-Sittaung canal. The output is a 10 m resolution Enhanced DEM (EnDEM) which is able to preserve the merits of all the input data, i.e., upper mountainous region, lower flat deltaic basin, and the river bathymetry. This paper provides a novel approach to DEM integration and burning of the river cross-section onto the DEM.

Maritime navigation is a complex task, involving an ever-increasing number of stakeholders and technologies. As complexity is growing, attention turns to the human element as the major cause of accidents and incidents. However, it is also the human element that might bring coherence and reasoning to the complex sociotechnical system that comprises maritime navigation. Thus, it is essential to develop an interpretative framework that could make sense of this complex system. This research project aims to enhance safety in maritime navigation, by developing a conceptual framework. This enables the design of Joint Cognitive System (JCS) in support of maritime navigation, including unmanned vessels, by focusing on the interactions. Results suggest that common ground is created in two dimensions: control system and shared domain. It is also found that planning helps to create a common cognitive map that supports the distributed control of the JCS.

The accuracy of topographic correction of Landsat data based on a Digital Surface Model (DSM) depends on the quality, scale and spatial resolution of the DSM data used and the co-registration between the DSM and the satellite image. A physics-based bidirectional reflectance distribution function (BRDF) and atmospheric correction model in conjunction with a 1-second DSM was used to conduct the analysis in this paper. The results show that for the examples used from Australia, the 1-second DSM, can provide an effective product for this task. However, it was found that some remaining artefacts in the DSM data, originally due to radar shadow, can still cause significant local errors in the correction. Where they occur, false shadows and over-corrected surface reflectance factors can be observed. More generally, accurate co-registration between satellite images and DSM data was found to be critical for effective correction. Mis-registration by one or two pixels could lead to large errors of retrieved surface reflectance factors in gully and ridge areas. Using low-resolution DSM data in conjunction with high-resolution satellite images will also fail to correct significant terrain components where they occur at the finer scales of the satellite images. DSM resolution appropriate to the resolution of satellite image and the roughness of the terrain is needed for effective results, and the rougher the terrain, the more critical will be the accurate registration.

Morphometric analysis of watersheds: A comprehensive review of data sources, quality, and geospatial techniques

High-alpine areas are subject to rapid topographic changes, mainly caused by natural processes like glacial retreat and other geomorphological processes, and also due to anthropogenic interventions like construction of slopes and infrastructure in skiing resorts. Consequently, the demand for highly accurate digital terrain models (DTMs) in alpine environments has arisen. Public administrations often have dedicated resources for the regular monitoring of glaciers and natural hazard processes. In case of glaciers, traditional monitoring encompasses in-situ measurements of area and length and the estimation of volume and mass changes. Next to field measurements, data for such monitoring programs can be derived from DTMs and digital ortho photos (DOPs). Skiing resorts, on the other hand, require DTMs as input for planning and – more recently – for RTK-GNSS supported ski-slope grooming. Although different in scope, the demand of both user groups is similar: high-quality and up-to-date terrain data for extended areas often characterised by difficult accessibility and large elevation ranges. <br><br>Over the last two decades, airborne laser scanning (ALS) has replaced photogrammetric approaches as state-of-the-art technology for the acquisition of high-resolution DTMs also in alpine environments. Reasons include the higher productivity compared to (manual) stereo-photogrammetric measurements, canopy-penetration capability, and limitations of photo measurements on sparsely textured surfaces like snow or ice. Nevertheless, the last few years have shown strong technological advances in the field of aerial camera technology, image processing and photogrammetric software which led to new possibilities for image-based DTM generation even in alpine terrain. At Vermessung AVT, an Austrian-based surveying company, and its subsidiary Terra Messflug, very promising results have been achieved for various projects in high-alpine environments, using images acquired by large-format digital cameras of Microsoft’s UltraCam series and the in-house processing chain centred on the Dense-Image-Matching (DIM) software SURE by nFrames. <br><br> This paper reports the work carried out at AVT for the surface- and terrain modelling of several high-alpine areas using DIM- and ALS-based approaches. A special focus is dedicated to the influence of terrain morphology, flight planning, GNSS/IMU measurements, and ground-control distribution in the georeferencing process on the data quality. Based on the very promising results, some general recommendations for aerial photogrammetry processing in high-alpine areas are made to achieve best possible accuracy of the final 3D-, 2.5D- and 2D products.

Landscape-scale geomorphic change detection: Quantifying spatially variable uncertainty and circumventing legacy data issues

In remote sensing, Digital Terrain Models (DTM) generation is a long-standing problem involving bare-terrain extraction and surface reconstruction to estimate a DTM from a Digital Surface Model (DSM). Most existing methods (including commercial software packages) have difficulty handling large-scale satellite data of inhomogeneous quality and resolution, and often need an expert-driven manual parameter-tuning process for each geographical type of DSM. In this paper we propose an automated and versatile DTM generation method from satellite data that is perfectly suited to large-scale applications. A novel set of feature descriptors based on multiscale morphological analysis are first computed to extract reliable bare-terrain elevations from DSMs. This terrain extraction algorithm is robust to noise and adapts well to local reliefs in both flat and highly mountainous areas. Then, we reconstruct the final DTM mesh using relative coordinates with respect to the sparse elevations previously detected, and induce preservation of geometric details by adapting these coordinates based on local relief attributes. Experiments on worldwide DSMs show the potential of our approach for large-scale DTM generation without parameter tuning. Our system is flexible as well, as it allows for a straightforward integration of multiple external masks (e.g., forest, road line, buildings, lake, etc) to better handle complex cases, resulting in further improvements of the quality of the output DTM.