103 research outputs found

    The Design of an Uncertainty Model For The Tidal Constituent and Residual Interpolation (TCARI) Method for Tidal Correction of Bathymetric Data

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    Recent advances in processing multibeam sonar data brought about by the Combined Uncertainty and Bathymetric Estimator (CUBE) [1] have demonstrated the value of identifying and tracking survey uncertainties. Most of these uncertainties were outlined in Hare, Godin, and Mayer uncertainty model developed in 1995 [2]. That report identified the uncertainties in the various electronic systems used to acquire the bathymetric data. However, one of the largest contributors to the overall error budge t in a near coastal hydrographic survey is that contributed by water level uncertainty. As the ocean mapping industry pushes for ever finer spatial details in its data, the traditional method of discrete tide zoning [3] must be abandoned for a more robust method that can match the requirements of the data. The method currently under investigation by the National Oceanic and Atmospheric Administration is the Tidal Constituent And Residual Interpolation (TCARI) method [4]. TCARI has the ability to interpolate the water level at a vessel’s position for any location and instance in time. It can also produce a gridded water level surface of the entire survey area. While the potential of this method is encouraging, a rigorous investigation of the uncertainties associated with it has yet to be completed. This research seeks to close that gap by examining the uncertainties in this method, using both observed water level information from around the country as well as data acquired during the original 1995 NOS Kinematic GPS experiment in Galveston Bay, Texas [5]

    Panoramic Images for Situational Awareness in a 3D Chart-of-the-Future Display

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    Many early charts featured sketches of the coastline, providing a good picture of what the shore looked like from the bridge of a ship. These helped the mariner to distinguish one port from another during an approach and establish their rough position within that approach. More recent experimental 3D chart interfaces have incorporated 3D models of land topography and man-made structures to perform the same function. However, topography is typically captured from the air, by means of stereophotogrammetry or lidar and fails to present a good representation of what is seen from a vessel’s bridge. We have been conducting an investigation of ways to present photographic imagery to the mariner to better capture the utility of the early coastline sketches. Our focus has been on navigation in restricted waters, using the Piscataqua River as a test area. This is part of our “Chart-of-the-Future” project being conducted by The Data Visualization Research Lab at the UNH Center for Coastal and Ocean Mapping. Through our investigation, we have developed a new method for presenting photographic imagery to the mariner, in the form of a series of panoramic images progressing down the channel. The panoramas consist of images stitched almost seamlessly together into circular arcs, whose centers are intended to be close to the position of a vessel’s bridge during transit. When viewed from this center, there is no distortion, and distortion increases to a maximum between two panorama centers. Our preliminary trials suggest that panoramas can provide an excellent supplement to electronic navigation aids by making them visible in the context of what can be seen out the window. We believe panoramas will be especially useful both in familiarizing a mariner with an unfamiliar approach during planning, and in enhancing situational awareness at times of reduced visibility such as in fog, dusk, or nightfall

    Tide Aware ENC: Demonstration of an Operational Concept

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    Application of High-precision Timing Systems to Distributed Survey Systems

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    In any hydrographic survey system that consists of more than one computer, one of the most difficult integration problems is to ensure that all components maintain a coherent sense of time. Since virtually all modern survey systems are of this type, timekeeping and synchronized timestamping of data as it is created is of significant concern. This paper describes a method for resolving this problem based on the IEEE 1588 Precise Time Protocol (PTP) implemented by hardware devices, layered with some custom software called the Software Grandmaster (SWGM) algorithm. This combination of hardware and software maintains a coherent sense of time between multiple ethernet-connected computers, on the order of 100 ns (rms) in the best case, of the timebase established by the local GPS-receiver clock. We illustrate the performance of this techniques in a practical survey system using a Reson 7P sonar processor connected to a Reson 7125 Multibeam Echosounder (MBES), integrated with an Applanix POS/MV 320 V4 and a conventional data capture computer. Using the timing capabilities of the PTP hardware implementations, we show that the timepieces achieve mean (hardware based) synchronization and timestamping within 100-150 ns (rms), and that the data created at the Reson 7P without hardware timestamps has a latency variability of 28 ”s (rms) due to software constraints within the capture system. This compares to 288 ms (rms) using Reson’s standard hybrid hardware/software solution, and 13.6 ms (rms) using a conventional single-oscillator timestamping model

    Facilitating collaboration in e-supply chain systems: an action learning-based approach

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    Increasingly, organisations are emphasizing more cooperative trading relationships with the view to constructing long-term collaborative partnerships. Often firms introduce Internet-based systems to integrate strategic suppliers into collaborative networks. In reality, many of these collaborative supply chain systems have underperformed or been terminated. Frequently these inter-organisational systems achieve gains in operational performance but fall short of relationship change. However to maximise the potential of an integrated system, participants need to learn ‘the art of collaboration’ with supply chain partners and manage a difficult change process. Achieving a successful implementation requires a formal intervention programme that facilitates behavioural change to improve integration within the network. One practical intervention technique is “action learning”. This approach focuses on learning from experience in an applied organisational context to cultivate behavioural change and collaborative practice. In this paper, the authors identify the key elements of an action learning programme created to promote behavioural change in the implementation of an Internet-based collaborative supply chain system. Based upon empirical data from an EC-Funded Fifth Framework Project, the impact of this formal integration programme is assessed

    Fusing Information in a 3D Chart-of-the-Future Display

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    The Data Visualization Research Lab at the Center for Coastal and Ocean Mapping is investigating how three-dimensional navigational displays can most effectively be constructed. This effort is progressing along multiple paths and is implemented in the GeoNav3D system, a 3D chart-of-the-future research prototype. We present two lines of investigation here. First, we explore how tide, depth, and planning information can be combined (fused) into a single view, in order to give the user a more realistic picture of effective water depths. In the GeoNav3D system, 3D shaded bathymetry, coded for color depth, is used to display navigable areas. As in ENC displays, different colors are used to easily identify areas that are safe, areas where under-keel clearance is minimal, and areas where depths are too shallow. Real-time or model-generated tide information is taken into account in dynamically color-coding the depths. One advantage to using a continuous bathymetric model, versus discrete depth areas, is that the model can be continuously adjusted for water level. This concept is also extended for planning purposes by displaying the color-coded depths along a proposed corridor at the expected time of reaching each point. In our second line of investigation, we explore mechanisms for linking information from multiple 3D views into a coherent whole. In GeoNav3D, it is possible to create a variety of plan and perspective views, and these views can be attached to moving reference frames. This provides not only semi-static views such as from-the-bridge and under-keel along-track profile views, but also more dynamic, interactive views. These views are linked through visual devices that allow the fusion of information from among the views. We present several such devices and show how they highlight relevant details and help to minimize user confusion. Investigation into the utility of various linked views for aiding realsituation decision-making is ongoin

    The Open Navigation Surface Project

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    Many hydrographic and oceanographic agencies have moved or are moving towards gridded bathymetric products. However, there is no accepted format to allow these grids to be exchanged while maintaining data and metadata integrity. This paper describes the Open Navigation Surface (ONS) Project, which aims to fill this gap. The ONS Project is an open-source software project designed to provide a freely available, portable source-code library to encapsulate gridded bathymetric surfaces with associated uncertainty values. The data file format is called a Bathymetric Attributed Grid (BAG). The BAG is developed and maintained by the ONS Working Group (ONSWG), and the source code is available via the ONS websit

    Electronic Chart of the Future: The Hampton Roads Project

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    ECDIS is evolving from a two-dimensional static display of chart-related data to a decision support system capable of providing real-time or forecast information. While there may not be consensus on how this will occur, it is clear that to do this, ENC data and the shipboard display environment must incorporate both depth and time in an intuitively understandable way. Currently, we have the ability to conduct high-density hydrographic surveys capable of producing ENCs with decimeter contour intervals or depth areas. Yet, our existing systems and specifications do not provide for a full utilization of this capability. Ideally, a mariner should be able to benefit from detailed hydrographic data, coupled with both forecast and real-time water levels, and presented in a variety of perspectives. With this information mariners will be able to plan and carry out transits with the benefit of precisely determined and easily perceived underkeel, overhead, and lateral clearances. This paper describes a Hampton Roads Demonstration Project to investigate the challenges and opportunities of developing the “Electronic Chart of the Future.” In particular, a three-phase demonstration project is being planned: 1. Compile test datasets from existing and new hydrographic surveys using advanced data processing and compilation procedures developed at the University of New Hampshire’s Center for Coastal and Ocean Mapping/Joint Hydrographic Center (CCOM/JHC); 2. Investigate innovative approaches being developed at the CCOM/JHC to produce an interactive time- and tide-aware navigation display, and to evaluate such a display on commercial and/or government vessels; 3. Integrate real-time/forecast water depth information and port information services transmitted via an AIS communications broadcast

    Cryptic multicolored lizards in the Polychrus marmoratus Group (Squamata: Sauria: Polychrotidae) and the status of Leiolepis auduboni Hallowell

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    The Neotropical genus Polychrus contains seven species of arboreal lizards. The type species for the genus is the widespread Polychrus marmoratus. We compared a few populations of P. marmoratus using 16S and COI mitochondrial gene sequences (1,035 bp total) and found several lineages existing under the name Polychrus marmoratus. Working backwards, using morphology we identify Polychrus marmoratus from the Guiana Shield and resurrect the name Leiolepis auduboni Hallowell for the species present in Trinidad, Tobago, and northern Venezuela. The number of species in the genus Polychrus is raised to eight. However, we also discuss evidence for the existence of other cryptic species withi
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