Satellite-Derived Bathymetry Using Multiple Images: The Alaska North Slope Case Study

Currently, charting data in much of the U.S. Arctic North Slope is inadequate or nonexistent and most of its areas have not been updated since the early-1950s. Although the charting infrastructure is out of date, ship transportation (such as, fishing and transit between the towns) has increased. NOAA conducted a preliminary multibeam survey in 2013 that reached Point Barrow, AK. However, all the Arctic North Slope remained untouched. Previous studies have shown that satellite-derived bathymetry (SDB) is a useful reconnaissance tool in tropical and sub-tropical waters in clear water conditions, especially over sandy seafloor. However, it is very difficult to extract good information over the Arctic using a single satellite image, especially over the U.S. North Slope. The glacial powder from land reduces the water clarity that limits the light penetration depth. Also, this turbidity is not uniform along the coast line and may affect the calculations. In this paper, a new SDB approach was developed that compiles multiple satellite images to extract only areas that were identified clear by comparison (i.e., minimum water clarity change between two satellite images). Preliminary results using Landsat 7 imagery from 1999-2002 and Landsat 8 imagery from 2013 are presented

Nautical Chart Adequacy Evaluation Using Publicly-Available Data

The International Hydrographic Office (IHO) C-55 publication communicates the need to improve the collection, quality and availability of hydrographic data world-wide, while also monitoring and rectifying possible deficiencies and shortcomings that are presented on the chart. This task of evaluating the adequacy of nautical chart products poses a challenge to many national hydrographic offices. This stems from the dearth of readily available spatial information: namely, the lack of reliable and accessible vessel traffic data, and little means to assess the changing nature of both near-shore bathymetry and shoreline in a simple and reliable manner. In this paper, we present the potential use of automatic-identification system (AIS) data, satellite-derived bathymetry (SDB), and airborne-lidar bathymetry (ALB) to provide an operational procedure for evaluating the adequacy and completeness of information of NOAA charts. Preliminary results from three U.S. study sites are presented in this paper: Nantucket Sound, MA; Barnegat Bay Inlet, NJ; and Barataria Bay, LA. Based on the publically-available datasets it was possible to identify changes in the charts and develop a reconnaissance procedure to monitor these changes on a yearly basis

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

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

GeoZui3D: Data Fusion for Interpreting Oceanographic Data

GeoZui3D stands for Geographic Zooming User Interface. It is a new visualization software system designed for interpreting multiple sources of 3D data. The system supports gridded terrain models, triangular meshes, curtain plots, and a number of other display objects. A novel center of workspace interaction method unifies a number of aspects of the interface. It creates a simple viewpoint control method, it helps link multiple views, and is ideal for stereoscopic viewing. GeoZui3D has a number of features to support real-time input. Through a CORBA interface external entities can influence the position and state of objects in the display. Extra windows can be attached to moving objects allowing for their position and data to be monitored. We describe the application of this system for heterogeneous data fusion, for multibeam QC and for ROV/AUV monitoring

Electronic Chart of the Future: The Hampton Roads Project

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

Discovery of Marine Datasets and Geospatial Metadata Visualization

NOAA\u27s National Geophysical Data Center (NGDC) provides the deep archive of US multibeam sonar hydrographic surveys. NOAA stores the data as Bathymetric Attributed Grids (BAG; http://www.opennavsurf.org/) that are HDF5 formatted files containing gridded bathymetry, gridded uncertainty, and XML metadata. While NGDC provides the deep store and a basic ERSI ArcIMS interface to the data, additional tools need to be created to increase the frequency with which researchers discover hydrographic surveys that might be beneficial for their research. Using Open Source tools, we have created a draft of a Google Earth visualization of NOAA\u27s complete collection of BAG files as of March 2009. Each survey is represented as a bounding box, an optional preview image of the survey data, and a pop up placemark. The placemark contains a brief summary of the metadata and links to directly download of the BAG survey files and the complete metadata file. Each survey is time tagged so that users can search both in space and time for surveys that meet their needs. By creating this visualization, we aim to make the entire process of data discovery, validation of relevance, and download much more efficient for research scientists who may not be familiar with NOAA\u27s hydrographic survey efforts or the BAG format. In the process of creating this demonstration, we have identified a number of improvements that can be made to the hydrographic survey process in order to make the results easier to use especially with respect to metadata generation. With the combination of the NGDC deep archiving infrastructure, a Google Earth virtual globe visualization, and GeoRSS feeds of updates, we hope to increase the utilization of these high-quality gridded bathymetry. This workflow applies equally well to LIDAR topography and bathymetry. Additionally, with proper referencing and geotagging in journal publications, we hope to close the loop and help the community create a true “Geospatial Scholar” infrastructure