Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Utility Patent
1997-04-15
2001-01-02
Zimmerman, Mark (Department: 2772)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
C345S421000, C345S426000, C345S182000, C345S182000
Utility Patent
active
06169552
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a map display device for displaying a three-dimensional map on a screen of a display device.
2. Description of Related Art
A navigation device has been hitherto known as means of improving the convenience of running of a car. According to this type of navigation device, two-dimensional map vector data which are stored in a storage medium such as a CD-ROM or the like are read out to form a two-dimensional map in which map constituents such as buildings, roads, geographical features, etc. are shown, and the two-dimensional map thus formed is displayed on a display screen of a monitor or the like. Further, a current position (the position of a car), a destination, a route connecting the current position and the destination, etc. are displayed on the display screen while superposed on the two-dimensional map.
According to the above-described prior art, the navigation device is improved so that a user can readily grasp surrounding conditions around the current position by changing the display scale of the two-dimensional map on the display screen or displaying the two-dimensional map in a bird's-eye view mode on the display screen.
SUMMARY OF THE INVENTION
However, the improvement of the processing on the screen display in the conventional navigation device as described above is performed on the basis of the two-dimensional map. Accordingly, when the current position or the destination is located on a multilevel crossing or a sloping road, or on a road along which many buildings stand, it is difficult to grasp the surrounding conditions of the current position or the destination because the surrounding conditions of these multilevel crossing, the sloping road, etc. are displayed two-dimensionally. Therefore, in order to make it easier to grasp the conditions of the circumferences of the current position and the destination, it is desirable to implement a navigation device for performing a three-dimensional map display in which a projection map to be obtained by viewing a three-dimensional map from any view point is displayed on the display screen.
If the navigation device for displaying the three-dimensional map is implemented, there might occur a case where a map constituent to be noted is hidden by another map constituent and thus it is not displayed on the display screen. In this case, there might also occur a problem that information such as a current position, a destination, a route connecting the current position and the destination or the like which a user wishes to know is not displayed on the screen.
Further, there might also occur a problem that visibility of attendant (related) information which is connected with each of map constituents such as buildings, roads, geographical features, etc. is much lower compared with a case where a two-dimensional map is displayed on the screen.
The present invention has been implemented on the basis of the foregoing situation, and a first object of the present invention is to provide a map display device for performing a three-dimensional map display, which can display on a display screen even information which is located at a position where the information would be hidden.
A second object of the present invention is to provide a map display device for performing a three-dimensional map display, which can prevent degradation in visibility of attendant information connected to map constituents.
In order to attain the first object, according to a first aspect of the present invention, a map display device for displaying a map on a display screen comprises: a map storage unit for storing three-dimensional data of plural map constituents which constitute a three-dimensional map; a map constituent specifying unit for specifying a desired map constituent; and a map display unit for projecting each map constituent specified by the three-dimensional data stored in the map storage unit from a desired view point onto a plane to form a three-dimensional bird's-eye view map, and displaying the three-dimensional bird's-eye view map on the display screen, wherein the map display unit includes projection mode changing means for changing a projection mode in which a desired map constituent specified by the map constituent specifying unit or another map constituent which is nearer to the desired view point than the desired map constituent concerned is projected on the plane, when the desired map constituent concerned is hidden by the other map constituent and thus the desired map constituent is not displayed on the three-dimensional bird's-eye view map, whereby the desired map constituent which would be originally hidden by the other map constituent can be displayed on the display screen.
Here, the map display unit may include view-point position changing means for changing the position of the desired view point to another position at which the desired map constituent can be displayed on the three-dimensional bird's-eye view map, when the desired map constituent specified by the map constituent specifying unit is hidden by the other map constituent which is located nearer to the desired view point than the desired map constituent and thus the desired map constituent is not displayed on the three-dimensional bird's-eye view map.
Further, the map display unit may include two-dimensional map display means for forming a two-dimensional map on the basis of two-dimensional data of each map constituent and displaying the two*dimensional map on the display screen in place of the three-dimensional bird's-eye view map when the desired map constituent specified by the map constituent specifying unit is hidden by the other map constituent which is located nearer to the desired view point than the desired map constituent and thus the desired map constituent is not displayed on the three-dimensional bird's-eye view map.
Still further, the map display unit may include two-dimensional map bird's-eye view display means for forming, on the basis of two-dimensional data of each map constituent, a two-dimensional bird's-eye view map which is obtained when a two-dimensional map is viewed from a desired view point, and displaying the two-dimensional bird's-eye view map on the display screen in place of the three-dimensional bird's-eye view map when the desired map constituent specified by the map constituent specifying unit is hidden by the other map constituent which is located nearer to the desired view point than the desired map constituent and thus the desired map constituent is not displayed on the three-dimensional bird's-eye view map.
Still further, the map display unit may include duplicative display means for forming a two-dimensional map on the basis of two-dimensional data of each map constituent and displaying the two-dimensional map on the display screen together with the three-dimensional bird's-eye view map when the desired map constituent specified by the map constituent specifying unit is hidden by the other map constituent which is located nearer to the desired view point than the desired map constituent and thus the desired map constituent is not displayed on the three-dimensional bird's-eye view map.
In addition, the map display unit may include duplicative display means for forming, on the basis of two-dimensional data of each map constituent, a two-dimensional bird's-eye view map which is obtained when a two-dimensional map is viewed from a desired view point, and displaying the two-dimensional bird's-eye view map on the display screen together with the three-dimensional bird's-eye view map when the desired map constituent specified by the map constituent specifying unit is hidden by the other map constituent which is located nearer to the desired view point than the desired map constituent and thus the desired map constituent is not displayed on the three-dimensional bird's-eye view map.
In the first aspect of the present invention, in order to form a three-dimensional bi
Endo Yoshinori
Okude Mariko
Nguyen Kimbinh T.
Pennie & Edmonds LLP
Xanavi Informatics Corporation
Zimmerman Mark
LandOfFree
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