Computer graphics processing and selective visual display system – Image superposition by optical means
Reexamination Certificate
1997-02-07
2001-01-30
Shalwala, Bipin (Department: 2778)
Computer graphics processing and selective visual display system
Image superposition by optical means
C345S009000, C359S630000, C359S632000, C348S113000
Reexamination Certificate
active
06181302
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to novel, improved navigation aids and, more specifically, to marine binoculars augmented with a visual display of navigation information and to marine navigation systems employing such binoculars.
BACKGROUND OF THE INVENTION
Ships and boats at sea need a variety of information in order to navigate safely. This information includes: the vessel's position relative to its planned course; the vessel's position relative to visible navigation hazards such as land masses and other ships; and the vessel's position relative to hidden hazards such as submerged rocks, channel boundaries, shipping lane separation zones, and restricted areas. The mariner acquires this information in a number of ways.
The first is by visual reference. By monitoring the vessel's position relative to known points of land, often with the aid of a compass, the navigator can triangulate the ship's position relative to its intended course. By monitoring other vessels, the navigator calculates whether a course change will be required to avoid a collision. And, by monitoring the ship's position relative to buoys, lights, and other visual aids to navigation, the mariner can also avoid some of the unseen hazards to navigation.
This same information is commonly augmented by radar which also displays the ship's position relative to visible hazards such as land masses and other vessels. In addition, the radar, with input from the ship's gyro or magnetic compass, can more accurately calculate range and bearing and perform collision avoidance calculations.
To best avoid unseen navigation hazards such as submerged rocks, the navigator needs to continuously calculate the absolute geographic position of the vessel and plot that position against a nautical chart on which the hidden hazards to navigation are indicated. This process is greatly facilitated by use of a Global Positioning Systems (GPS) receiver and an Electronic Chart System (ECS). The ECS displays a digital representation of a conventional paper nautical chart. On this chart, the ECS overlays the position of the ship based on input from the GPS. The ECS usually consists of a navigation computer containing an electronic nautical chart (ENC) database, interfaces to navigation sensors such as those identified below, and a fairly high resolution computer display screen.
While the ECS represents a vast improvement over manually plotting the ship's position against a paper chart, it has a number of drawbacks and limitations. The first is that it is often difficult to relate: (a) the information in the electronic chart display (usually oriented course-up) with (b) the real world as seen from the navigator's field of view (often a completely different direction). A second significant limitation is that the ECS requires a color, fairly high resolution (therefore fairly large size) display to be most effective. Many mariners, however, navigate from an open cockpit or a flying bridge conning station. There, the lack of space, glare from direct sunlight, and exposure to the elements limit the utility of an ECS display.
Others have attempted to improve marine navigation by augmenting marine binoculars with information pertinent to navigation. Heretofore, these attempts have been limited to adding only bearing and, in a few cases, distance information. This information is at best of limited utility in identifying hidden obstacles and other unseen hazards to navigation. Furthermore, these products usually split the field of view between the real world image and an image of a compass, using mirrors and normal lens optics. This is awkward and can actually distract from instead of enhance the real world image available to the mariner.
From the foregoing, it will be apparent to the reader that there is a present and continuing need for better aids to marine navigation.
SUMMARY OF THE INVENTION
The need for improved navigation aids has now to a significant extent been satisfied by instruments which embody the principles of the present invention and are referred to hereinafter as “nav glasses.”
Nav glasses are, generally speaking, marine binoculars augmented with a see-through, computer-generated overlay or display of navigation information. The computer-generated display is superimposed on the real world image available to the user.
Nav glasses also have the components needed to link them to the navigation computer which is utilized to generate the see-through display of navigation information. Also, they typically are equipped with instruments such as a fluxgate compass and an inclinometer for acquiring azimuth and inclination information needed by the navigation computer. In appropriately configured navigation systems, the nav glasses can be employed to lock onto a moving target, which can then be tracked by onboard radar.
The navigation systems in which the nav glasses are incorporated also accept inputs from other sources such as a compass, a GPS, and other navigation aids; a route planning system; and onboard radar. The field of view of the nav glasses is calculated from information obtained from the nav glasses and navigation sensors, and a display manager generates a pre-fetch display of navigation information from the route planning and radar inputs. This pre-fetch display or image extends well beyond the nav glass field of view. Consequently, as the glasses are shifted from side-to-side or up or down, all that is required to match the virtual display to the real world image is to align a different segment of the pre-fetch image with the actual field of view. This is an important feature of the present invention inasmuch as the just-described approach is much faster then generating a new virtual image each time the nav glasses are shifted. If the field of view lies beyond the boundaries of the current pre-fetch image or overlay, a flag is raised; and a new pre-fetch overlay is generated and aligned with the current field of view.
Once the alignment of the virtual display of navigation information and actual field of view is completed, the virtual overlay is transmitted in digital form to a video output component of the navigation computer and forwarded to the nav glasses where the virtual display is constructed and superimposed on the real world field of view. Also important is a navigation system feature which allows additional, textual information to be added to the virtual display at the option of the user of the nav glasses. The user also has the option of canceling the display of the additional information at any time.
The advantages, features, and objects of the present invention will be apparent to the reader from the foregoing and the appended claims and as the detailed description and discussion of the invention proceeds in conjunction with the accompanying drawings.
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Anderson Ronald M.
Lewis David L.
Shalwala Bipin
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