TALOSS: Three-Dimensional Advanced Localization Observation Submarine Software
The 3-D undersea battlespace display receives its tactical information from the Feeder program. It receives mapping and navigational information from the Digital Nautical Chart database that is loaded at startup and updated based on the evolution of the tactical situation. All navigational information is pre-rendered as Open Inventor binary files, called Navigation Tiles. The Main App combines all tactical and navigation information into a comprehensive 3-D picture, rendering it using the computer platform-independent scenegraph, Open Inventor.
The lower-left corner of the 3-D display contains three scene interaction controls. The Rotx dolly rotates the scene about an imaginary x-axis running horizontally across the screen. The Roty dolly rotates the scene about an imaginary y-axis running vertically across the screen. The vertical exaggeration slider bar changes the depth ratio of the scene. This serves to exaggerate 3-D depth within the scene. To use any of these dolly wheels, simply place the mouse cursor over the dolly, depress and hold the left button while dragging the cursor in the desired direction. The lower-right corner of the 3-D display contains a zoom dolly. Zoom-in is limited to collision with the bottom, at which point zoom ceases.
In addition to scene manipulation devices, the 3-D display contains seven interaction buttons. The buttons perform functions such as selecting a contact, scene manipulation, resetting a home view and toggling a wire-frame view.
Some other 3-D display features of note are a free-floating 3-D compass that simultaneously indicates both direction and 3-D scene orientation and a colorbar that indicates depth shading. Depth shading is a combination of color map and depth regime selected. Figure 4 illustrates these features.
The purpose of a tactical display is to give an operator a sense of the location of everything relative to the operator's own position. This is accomplished in TALOSS by a series of concentric range rings centered about ownship. The range rings represent set intervals that allow an operator to determine instantly, visually, how far any particular object is from ownship. This information is particularly important in collision avoidance and threat assessment. These rings are shown both in the 3-D display and in the top-down view shown in the Bezel.
An essential component of any tactical or situational awareness display is precise knowledge of location on the earth. TALOSS supports navigational information using two methods. The first is a system of navigational grid markers that are ten degrees of latitude and longitude. Because distance is equal for all latitudes, this amounts to ten nautical miles for latitude. Because the distance between longitude lines varies with latitude, the number of nautical miles between longitude lines is dependent on latitude. For temperate latitudes, it is approximately ten nautical miles. Second, in addition to the lines of constant latitude/longitude, an alphanumeric value appears on the 3-D map indicating latitude and longitude. These values and the navigational grid lines are extracted from the Digital Nautical Chart database. The navigation grid toggles with the range ring display; however, the alphanumeric markers are always displayed. Figure 5 shows a view of the 3-D display with all navigational information enabled.
The most important component of a situational awareness display is the ability to track and to integrate all moving objects visually. In TALOSS, solid lines indicate the estimated tracks of all known objects. Associated with the tracks is a color scheme indicating intent, which can be hostile, friendly or neutral. The respective colors for these classifications are red, blue and yellow. Because the current version of TALOSS is designed for submarine applications, it also includes tracks for weapons, both ownship's and hostile. The coloring scheme is green for ownship's weapons and orange for hostile weapons. This color scheme, however, is easily modified for other applications. Figure 5 illustrates tracks on several contacts as well as ownship. All contacts have their tracks labeled as defined in the contact window of the Bezel.
In addition to tracking information, TALOSS does bookkeeping for potential danger zones as 3-D containment regions. The same color schemes used for tracks apply to these containment regions: red, blue and yellow. Figure 6 indicates a typical 3-D containment region. Containment regions are computed and displayed as complex volumetric shapes. Containment region selection is controlled by the Bezel. The Bezel allows for both containment region highlighting and selection of the contacts contributing to a particular containment region.
Containment regions can be grown and intersected to mimic a vessel's movement over time. Growth of the regions represents all possible locations the vessel could occupy within the containment volume when precise sensor contact on that vessel is lost. When a sensor update on the vessel is obtained, that updated information, in the form of new 3-D containment volume, can be intersected with the previously grown 3-D volume to extract a much-reduced common volume (see Figure 7). This common volume has the highest probability of containing the vessel of interest. The goal of a military combat system is to “localize” the threat containment volume rapidly, so an appropriate tactical response can be precipitated expeditiously. In other words, fight or flight.
Pioneering software in the intersection of two or more noncontiguous volumes has been developed for TALOSS by Arizona State University. One of the main advantages of using the Linux operating system for software development is that research into specific areas of interest can be done inexpensively at universities or other open-source sites. Using Linux means that the participating research partners do not need to buy expensive development platforms, such as Hewlett-Packard TAC or Silicon Graphics workstations. Instead, they can develop code easily integrated into a combat system on inexpensive Linux-based PC systems. The US government is encouraging the use of commercial-off-the-shelf (COTS) products for development and deployment in the US military, both as a cost-saving measure and as a means for ensuring widespread long-term support of the product. Using Linux as both a development and operational environment for military systems is a perfect example of COTS in action.
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