VBSS Databases

TYPES OF DATA BASES

By definition, a database is a collection of related computer records that can be accessed, manipulated or utilized in a systematic way. At the Computer Aided Operations Research Facility (CAORF), whereas the entire integrated model of a specific geographic area is referred to as a database, the model is actually comprised of six different databases.

The Visual Database is a model of all that is seen from ownship (the ship represented by the bridge simulator) as it traverses a waterway. All the buildings, buoys, landmasses, towers, tanks and traffic ships seen from ownship are included in this model. Any structure to be placed in the visual scene begins with a wire-frame model and ends with a colored, shaded and texture-mapped three-dimensional representation.

Typical buoy image construction for visual scene

The Radar Database is a network of line segments, polygons and discrete points organized in such a manner that when processed by the Radar Signal Generator (RSG) will produce a realistic radar image. Numerical data to this database define both terrain elevation and radar reflectivity.

The Situation Display Database is also referred to as the Instructor’s Station Database due to its use by instructors and control station operators to observe and coordinate simulator training sessions. It displays an idealized chart of a harbor area with coastal outlines, navigational aids, numerical depth soundings and channel markings. With this as a background, ships are displayed as they move through this area at various scales available via the Control Station.

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Completed radar and situation display databases, respectively.

The Depth Contour Database consists of a composite database built from various bathometric data available for a harbor area. The result produces a three-dimensional mesh that models the shape and contour of the ocean floor, and generates realistic depth sounding values when processed by the ship’s fathometer.

A Water Current Database consists of a collection of discrete points each containing individual water speed and direction values stored via fixed vector structures. Using this, proper forces can be calculated and exerted on both the ownship and traffic ships to produce realistic effects.

The Sound System Database replicates various aural cues, including specific ship sounds, environmental sounds, weather-related sounds, and sounds associated with certain navigational cues, along with directional and distance effects as one approaches or moves away from a specific sound source.

COLLECTION OF PERTINENT INFORMATION

The information needed to construct each database can be obtained from various sources, including: coordinate systems data supplied by the National Imagery and Mapping Agency (NIMA) or Army Corps of Engineers (ACOE), detailed bathometric readings supplied by the ACOE and facilities like the Engineering Research Development Center (ERDC), engineering drawings or blueprints, nautical charts, topographical maps, digitized data, tide and current tables, on-site photographs, and various observations supplied by expert mariners familiar with the geographic area to be modeled.

Similar information is needed for the construction of traffic ship and ownship bow models to be used in the related exercises. In addition, high-fidelity ship hydrodynamic effects supplied by Force Technology (formerly the Danish Maritime Institute) or similar facilities are used in the detailed modeling of all ship handling responses.

DATABASE CONSTRUCTION

The first step in the construction of a database is to prepare the charts and drawings to be used. This involves physically locating and labeling certain points, structures and reference lines by hand. The chart or drawing is then fixed to a special electronic table, called a Digitizer or Digitizing Tablet, where the various line segments, polygons and discrete data points are digitized.

GTCO™ Digitizing Tablet with a prepared chart attached.

The first database built is normally the Instructor’s Station Database. The original data file is run through various software programs with related data input in order to form the Situation Display.

The second database to be created is the Depth Contour Database. Various layers of the original data file, along with related tidal data, are run through a number of software programs in order to produce the three-dimensional mesh mentioned above.

The next database to be constructed is the Visual Database. Three dimensional structures are set up via MultiGen-Paradigm graphic software using the original data file, coordinate systems data, and various on-site photographs of the geographic area. Color and visual surface textures are associated with each structure at this time. It is during this intricate and time consuming process that the landmasses, navigational aids, traffic ships, ownships and miscellaneous buildings and structures are created as graphic computer files.

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Selected views from the New York Harbor and Norfolk Harbor visual databases.

The Radar Database is the fourth database to be constructed. The original MultiGen-Paradigm visual files and associated reflectivity data are run through an additional software program, and converted into a suitable format that can be processed by the RSG.

The next database to be constructed is the Water Current Database. Data files supplied by facilities such as the ERDC are run through an additional software program and converted into a suitable format that can be accessed by the simulator. An alternate method of construction is to use the Instructor’s Station Display as a backdrop and create current vectors containing velocity and phase angle information at discrete points via a software interface.

The Sound System Database is the only database that is not necessarily dependent on a specific geographic area. These sound files can be either associated directly with certain visual files during the creation process or activated on the simulator from the Control Station.

VALIDATION / REVISION

The various databases for a specific geographic area are then examined for accuracy and correctness first via various off-line workstations and plotting routines.

After all the databases have been examined offline, they then undergo preliminary online validation by members of the CAORF staff who check out all aspects of the databases for realism as well as accuracy. This online checkout involves various test runs on the bridge simulator, during which any inaccuracies to the database are noted. After the preliminary validation, the process is repeated in the form of a second inspection made by the individual client.

VBSS Control Station

In the case of a research and development project or outside commercial training, this inspection is normally conducted by expert mariners supplied by the client and familiar with the specific harbor area. If the database is to be used solely for the purpose of U.S. Merchant Marine Academy (USMMA) Midshipmen Training, the checkouts are performed by members of the Department of Marine Transportation located at the Academy.

Any necessary revisions or corrections to the databases are then implemented based upon these two validation sessions.

DATABASES CURRENTLY AVAILABLE

The following geographic databases are currently available for use at the Academy:

• Generic Open Sea • Kings Point, New York • New York Harbor, New York • Norfolk Harbor, Virginia • Port Cristobal, Panama • Rotterdam, Holland

• San Francisco Bay, California • Santa Barbara Channel, California • Santa Cruz Channel, California • Singapore Strait, Indonesia • Strait of Hormuz, Persian Gulf • Valdez, Alaska