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Academic literature on the topic 'Hydrographic'
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Journal articles on the topic "Hydrographic"
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Foroutan, Mina, Sonja Bhatia, and Geneviève Béchard. "The Hydrographer of the Future - Reflections on an international virtual workshop." International Hydrographic Review 28 (November 1, 2022): 172–80. http://dx.doi.org/10.58440/ihr-28-n12.
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The Canadian Hydrographic Service (CHS) expects the skillsets of its multidisciplinary hydrographers to evolve as the field of hydrography undergoes a digital transformation. To characterize these changes, the CHS organized a virtual workshop titled Hydrographer of the Future, in which it heard the perspectives of international colleagues in other Hydrographic offices (HO’s), industry, and academia. Despite some variations, common themes emerged: the changing technological context, people and culture, and the future role of hydrography. The results of this workshop support the CHS’ own internal planning; however, the CHS also hopes to continue learning from its international partners and share its experiences through the International Hydrographic Organization’s (IHO) e-learning center.
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Nakabayashi, Shigeru. "East Asia Hydrographic Commission - Fifty Years of Progress." International Hydrographic Review 27 (May 1, 2022): 99–112. http://dx.doi.org/10.58440/ihr-27-n06.
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The year 2021 marks the 50th anniversary of the East Asia Hydrographic Commission (EAHC). It was established in 1971 as the third oldest Regional Hydrographic Commission located in East Asia. Since then, EAHC has progressed in cooperation of hydrographic services and in development of hydrographic technology for navigation safety and other aims. This article describing comprehensive historical steps and efforts of a Regional Hydrographic Commission in an important area of maritime transport will present readers a suggestive model of regional cooperation in hydrography. One of the suggestions can be summarized that the keys to development of Regional Hydrographic Commission are strong intention, initiative, unity and enthusiasm to leave no one behind.
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Urbahs, Aleksandrs, Rima Mickevičienė, Vasilij Djačkov, et al. "Analysis of an Unmanned Aerial Vehicle Monitoring System for Resurveying of Shipping Routes." Transport and Aerospace Engineering 3, no. 1 (2016): 102–11. http://dx.doi.org/10.1515/tae-2016-0012.
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Abstract The paper gives brief description of the conventional and innovative hydrography survey methods and constraints connected with the realization. Proposed hydrographic survey system based on the use of Unmanned Aerial and Maritime systems provides functionality to conduct hydrographic measurements and environment monitoring. System can be easily adapted to fulfil marine safety and security operations, e.g. intrusion threat monitoring, hazardous pollutions monitoring and prevention operations, icing conditions monitoring.
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Samsonov, Timofey E. "Automated Conflation of Digital Elevation Model with Reference Hydrographic Lines." ISPRS International Journal of Geo-Information 9, no. 5 (2020): 334. http://dx.doi.org/10.3390/ijgi9050334.
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Combining misaligned spatial data from different sources complicates spatial analysis and creation of maps. Conflation is a process that solves the misalignment problem through spatial adjustment or attribute transfer between similar features in two datasets. Even though a combination of digital elevation model (DEM) and vector hydrographic lines is a common practice in spatial analysis and mapping, no method for automated conflation between these spatial data types has been developed so far. The problem of DEM and hydrography misalignment arises not only in map compilation, but also during the production of generalized datasets. There is a lack of automated solutions which can ensure that the drainage network represented in the surface of generalized DEM is spatially adjusted with independently generalized vector hydrography. We propose a new method that performs the conflation of DEM with linear hydrographic data and is embeddable into DEM generalization process. Given a set of reference hydrographic lines, our method automatically recognizes the most similar paths on DEM surface called counterpart streams. The elevation data extracted from DEM is then rubbersheeted locally using the links between counterpart streams and reference lines, and the conflated DEM is reconstructed from the rubbersheeted elevation data. The algorithm developed for extraction of counterpart streams ensures that the resulting set of lines comprises the network similar to the network of ordered reference lines. We also show how our approach can be seamlessly integrated into a TIN-based structural DEM generalization process with spatial adjustment to pre-generalized hydrographic lines as additional requirement. The combination of the GEBCO_2019 DEM and the Natural Earth 10M vector dataset is used to illustrate the effectiveness of DEM conflation both in map compilation and map generalization workflows. Resulting maps are geographically correct and are aesthetically more pleasing in comparison to a straightforward combination of misaligned DEM and hydrographic lines without conflation.
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Haslam, David. "The Duke of Edinburgh Lecture: International Hydrography." Journal of Navigation 46, no. 2 (1993): 159–73. http://dx.doi.org/10.1017/s0373463300011516.
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It is perhaps appropriate, on this the exact 187th anniversary of the death of Admiral Lord Nelson at Trafalgar and in the year in which so many celebrations have taken place to commemorate the 500th anniversary of Christopher Columbus's arrival somewhere in the West Indies, to consider the progress which has been made towards international co-operation and achievements in hydrographic surveying and nautical cartography, particularly since the formation of the International Hydrographic Bureau in 1921, and to look at the problems facing international hydrography in the immediate future.
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Atkinson, Larry P., Thomas N. Lee, Jackson O. Blanton, and Gustav-Adolf Paffenhöfer. "Hydrographic observations." Progress in Oceanography 19, no. 3-4 (1987): 231–66. http://dx.doi.org/10.1016/0079-6611(87)90010-3.
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Akpınar, Burak, and Nedim Onur Aykut. "Determining the Coordinates of Control Points in Hydrographic Surveying by the Precise Point Positioning Method." Journal of Navigation 70, no. 6 (2017): 1241–52. http://dx.doi.org/10.1017/s0373463317000236.
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After Global Navigation Satellite Systems (GNSS) were first used in the field of hydrography in 1980, developments in hydrographic surveying accelerated. Survey precision in hydrography has been improved for both horizontal and vertical positioning and seafloor acoustic measurement by means of these new developments. Differential Global Positioning System (DGPS), Real Time Kinematic (RTK) and Network RTK (NRTK) techniques are the satellite-based positioning techniques that are commonly used in shallow water surveys and shoreline measurements. In line with these developments, the newer Precise Point Positioning (PPP) has been introduced. Combining precise satellite positions and clocks with dual-frequency GNSS data, PPP can provide position solutions from the centimetre to decimetre level. In this study, the coordinates of control points were determined by using the Post-Process PPP (PP-PPP) technique. Seven test points, which are the points of the Continuously Operating Reference Station - Turkey (CORS-TR) network, are selected near the shorelines within Turkey. The 24-hour data was split from one to six hours by one hour periods. Automatic Point Positioning Service (APPS) was selected to process the data. The poisoning error of the test points were given and compared with International Hydrographic Organization (IHO) S44 hydrographic survey standards.
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Specht, Cezary. "Maritime DGPS System Positioning Accuracy as a Function of the HDOP in the Context of Hydrographic Survey Performance." Remote Sensing 15, no. 1 (2022): 10. http://dx.doi.org/10.3390/rs15010010.
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The Differential Global Positioning System (DGPS) is a marine navigation system operating at frequencies of 283.5–325 kHz, which is now the primary method for locating vessels in coastal shipping, as well as hydrography and mapping systems worldwide. Its positioning accuracy is determined by the following: the pseudorange error to Global Positioning System (GPS) satellites, the age of pseudorange corrections, and the value of the Horizontal Dilution Of Precision (HDOP), which, in terms of accuracy, is crucial in positioning using GPS satellites. In 2020, the International Hydrographic Organization (IHO) introduced a new (the highest) order of hydrographic surveys, i.e., the Exclusive Order, which requires a positioning system to provide an accuracy of 1 m (p = 0.95). The aim of this article is to provide an answer to the question as to whether the maritime DGPS system, whose positioning accuracy is constantly increasing with that of the GPS system, fulfils the requirements for the hydrographic surveys of harbours. To this end, an extensive experimental study on the maritime DGPS system, involving a total of nearly 3.5 million fixes, was conducted. Statistical analyses showed that when ensuring the HDOP values range from 0.8 to 1.4, the DGPS system can be used in hydrographic surveys of harbours.
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Voss, Rüdiger, Hans-Harald Hinrichsen, Daniel Stepputtis, et al. "Egg mortality: predation and hydrography in the central Baltic." ICES Journal of Marine Science 68, no. 7 (2011): 1379–90. http://dx.doi.org/10.1093/icesjms/fsr061.
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Abstract Voss, R., Hinrichsen, H-H., Stepputtis, D., Bernreuther, M., Huwer, B., Neumann, V., and Schmidt, J. O. 2011. Egg mortality: predation and hydrography in the central Baltic. – ICES Journal of Marine Science, 68: 1379–1390. Cod and sprat are the dominant fish species in the Baltic pelagic ecosystem, both of great economic importance and ecologically strongly interlinked. Management of both species is challenged by highly variable recruitment success. Recent studies have identified predation and hydrographic conditions during the egg phase to be of critical importance. Two years of extensive field investigations in the Bornholm Basin, central Baltic Sea, were undertaken. In 2002, a typical stagnation situation characterized by low salinity and poor oxygen conditions was investigated, and in early 2003, a major inflow of North Sea water completely changed the hydrographic conditions by increasing salinity and oxygen content, thereby altering ecological conditions. The goal was to quantify egg mortality caused by predation and hydrography, and to compare these estimates with independent estimates based on cohort analysis. Results indicated high intra-annual variability in egg mortality. Cod and sprat egg mortality responded differently to the major Baltic inflow: mortality related to hydrographic conditions increased for sprat and decreased for cod. On the other hand, predation mortality during peak spawning decreased for sprat and increased for cod.
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Stanislawski, Lawrence V., Ethan J. Shavers, Shaowen Wang, et al. "Extensibility of U-Net Neural Network Model for Hydrographic Feature Extraction and Implications for Hydrologic Modeling." Remote Sensing 13, no. 12 (2021): 2368. http://dx.doi.org/10.3390/rs13122368.
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Accurate maps of regional surface water features are integral for advancing ecologic, atmospheric and land development studies. The only comprehensive surface water feature map of Alaska is the National Hydrography Dataset (NHD). NHD features are often digitized representations of historic topographic map blue lines and may be outdated. Here we test deep learning methods to automatically extract surface water features from airborne interferometric synthetic aperture radar (IfSAR) data to update and validate Alaska hydrographic databases. U-net artificial neural networks (ANN) and high-performance computing (HPC) are used for supervised hydrographic feature extraction within a study area comprised of 50 contiguous watersheds in Alaska. Surface water features derived from elevation through automated flow-routing and manual editing are used as training data. Model extensibility is tested with a series of 16 U-net models trained with increasing percentages of the study area, from about 3 to 35 percent. Hydrography is predicted by each of the models for all watersheds not used in training. Input raster layers are derived from digital terrain models, digital surface models, and intensity images from the IfSAR data. Results indicate about 15 percent of the study area is required to optimally train the ANN to extract hydrography when F1-scores for tested watersheds average between 66 and 68. Little benefit is gained by training beyond 15 percent of the study area. Fully connected hydrographic networks are generated for the U-net predictions using a novel approach that constrains a D-8 flow-routing approach to follow U-net predictions. This work demonstrates the ability of deep learning to derive surface water feature maps from complex terrain over a broad area.