JP3438487B2 - Portable navigation device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable navigation device, and more particularly to a portable navigation device capable of converting map data into a top view or a bird's-eye view and displaying it on a display device.

[0002]

2. Description of the Related Art As a conventional navigation device, for example, an input device is provided, and there is an advantage that it is possible to switch between a two-dimensional map display in which a map is looked down from the top and a bird's-eye view map display according to the application. Those who have are known.

[0003]

However, in the conventional navigation device, in order to switch between the plan view display and the bird's-eye view display, the operator must understand the function of the input device before performing the display method. Since it has to be input and set, it is necessary to always be aware of the function and operation of the input device, and there is a problem that the operability becomes complicated and annoying.

The present invention has been made in view of the above, and an object thereof is to provide a portable navigation device capable of automatically switching the screen display according to the viewpoint of the operator.

[0005]

The invention according to claim 1 is
In order to solve the above problems, a portable navigation device that converts map data into a top view or a bird's-eye view and displays it on a display device, wherein the display device has a tilt angle measuring means for measuring a tilt angle, and a current position. And a position measuring means for measuring an azimuth angle, a viewpoint position calculating means for calculating a virtual viewpoint position representing a position of a virtual viewpoint based on the measured tilt angle, current position and azimuth angle, and the calculated and a map drawing means for outputting to the display device by converting the two-dimensional map data in accordance with the virtual viewpoint position, the viewpoint position calculation
The means determines the virtual viewpoint position according to the tilt angle of the display device.
The point is to change continuously .

[0006]

[0007]

[0008] According to a second aspect of the invention, for solving the above problems, the viewpoint position calculation means is a predetermined virtual viewpoint position is changed in accordance with the tilt angle of the display device as an extension line of sight The main idea is to set the height position.

[0009] The invention of claim 3, wherein, in order to solve the above problems, the viewpoint position calculation means, the virtual viewpoint position is changed in accordance with the tilt angle of the display device as an extension of the line of sight direction in advance from the current position The gist is to set the position at a specified distance.

[0010] The invention of claim 4, wherein, in order to solve the above problems, the viewpoint position calculation means, the virtual viewpoint position is changed in accordance with the tilt angle of the display device as an extension of the line of sight direction in advance from the current position The gist is to set the position at different altitudes at a specified distance.

According to a fifth aspect of the present invention, in order to solve the above-mentioned problems, the viewpoint position calculating means horizontally sets the inclination angle of the display device measured by the inclination angle measuring means on the basis of a threshold having hysteresis. The point is to judge whether or not.

[0012]

According to the present invention, the tilt angle of the display device is measured, and the current position and azimuth angle are measured. Here, the virtual viewpoint position representing the position of the virtual viewpoint is calculated based on the measured tilt angle, the current position and the azimuth angle, and then the map data is two-dimensionally converted according to the calculated virtual viewpoint position. And output to the display device . And
Depending on the tilt angle of the display device when calculating the virtual viewpoint position
The tilt angle by changing the virtual viewpoint position continuously.
As the inclination increases from the horizontal map display when horizontal
The bird's-eye view area where the down-looking angle of the viewpoint conversion is continuously reduced
The figure can be displayed.

[0013]

[0014]

According to the second aspect of the present invention, the virtual view point position that changes according to the tilt angle of the display device is set to a predetermined height position on the extension line of the line-of-sight direction. The area near the current location is enlarged as the distance to is approached, and the facilities and intersections near the current location can be easily recognized.

According to the third aspect of the present invention, the virtual viewpoint position which is changed according to the tilt angle of the display device is set to a position of a predetermined distance from the current position on the extension line of the line-of-sight direction. Since the distance from the current position is constant even if the look-down angle changes, the change in scale is small and the discomfort caused by switching can be reduced.

Further, according to the present invention of claim 4, the virtual viewpoint position which is changed according to the inclination angle of the display device is different from the current position on the extension line in the line-of-sight direction at a predetermined distance from the current position. By doing so, since the distance from the current position is constant even if the look-down angle changes, the change in scale is small and the discomfort caused by switching can be reduced.

According to the fifth aspect of the present invention, it is possible to prevent oscillation during screen switching by determining whether or not the tilt angle of the display device is horizontal with reference to a threshold having hysteresis. it can.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a diagram showing a system configuration of a portable navigation device 1 according to a first embodiment of the present invention. As shown in FIG. 1, the portable navigation device 1 includes a display device 11 that has a liquid crystal screen or the like and displays a display screen generated by a perspective conversion road screen generation unit 17, which will be described later, and an inclination angle of the display device 11. A tilt angle sensor 12 for measuring the current position and a GPS (global position) for measuring the current position and azimuth represented by latitude and longitude based on radio waves from a satellite received via an antenna (not shown). Positioning system) Receiver 13 and CD-
A viewpoint position calculation unit 16 that calculates a virtual viewpoint position based on the measurement values output from the CD-ROM device 14 for reading out the map data recorded in the ROM, the tilt angle sensor 12, and the GPS receiver 13. And a perspective conversion road screen generation unit 17 that generates a display screen by performing perspective conversion processing on map data including roads read from the CD-ROM device 14 and displays the display screen on the display device 11.

The viewpoint position calculation unit 16 and the perspective conversion road screen generation unit 17 are composed of a control device including a CPU, a ROM and a RAM. In addition, since the azimuth angle measured by the GPS receiver 13 is obtained based on the relative change in the position change, the azimuth angle is calculated based on the relative change in the position. Is
Since the measurement accuracy decreases, a geomagnetic azimuth sensor or a gyroscope may be built in to correct the azimuth.

FIG. 2 is an external view of the portable navigation device 1 according to the present invention. As shown in the figure, a display device 1 using a liquid crystal screen so that it can be used as a portable type.
1, a CD-ROM device 14, a GPS receiver 13, a tilt angle sensor 12 and a controller 15 are built in. As shown in the figure, the GPS receiver 13 and the tilt angle sensor 12
May be attached to the outside of the device or may be incorporated inside.

Next, referring to FIGS. 3 to 7, the controller 15
The calculation of the virtual viewpoint position and the drawing of the map screen by the perspective transformation of the map data will be described. In FIG. 3, in step S10, the viewpoint position calculation unit 16 determines the current position and azimuth having the latitude and longitude measured by the GPS receiver 13,
The virtual viewpoint position is calculated based on the tilt angle measured by the tilt angle sensor 12.

Here, a method of calculating the virtual viewpoint position will be described. As shown in FIG. 4, the inclination angle sensor 12 measures the inclination angle α ° with reference to the horizontal position of the main body. Assuming that the operator is looking at the display device 11 from the front, the vertical direction AB of the display device 11 is the line-of-sight direction. The virtual viewpoint position is set on the extension line of the line-of-sight direction AB. here,
The relationship between the line-of-sight looking-down angle θ and the inclination angle α ° is θ + α = 90 ° (Equation 1).

When the inclination angle α ° is smaller than the reference value k ° with reference to the horizontal position of the display device 11 based on the measurement value of the inclination angle sensor 12, the virtual viewpoint position is set vertically to the current position. Set on. On the other hand, the inclination angle α ° is the reference value k
If it exceeds 0, the virtual viewpoint position is set to a position that is relatively determined in advance behind the current position. Next, step S
In 20, the perspective conversion road screen generation unit 17 converts the map data read from the CD-ROM device 14 according to the current position into a road image by the perspective conversion processing based on the virtual viewpoint position calculated in step S10. To generate.

Here, a method of calculating perspective transformation will be described.
The map data read from the CD-ROM device 14 is
As in the xy plane shown in FIG. 5, the position is represented by latitude / longitude or a format corresponding to it (hereinafter, referred to as map coordinates). The map data represented by the map coordinates is converted into the display coordinates of the display device 11 based on the perspective conversion to generate the road image.

More specifically, as shown in FIG. 5, the current position G
On the other hand, the virtual viewpoint position P calculated by the viewpoint position calculation unit 16 is set as the projection point O in the map coordinates on the xy plane. y
Two-dimensional conversion of map data of map coordinates, that is, movement conversion and rotation conversion, is performed on a display plane in which the direction perpendicular to the coordinates is the z coordinate. For example, a trapezoidal area composed of the points ABCD on the xy plane represented by the map coordinates corresponds to the display screen represented by the display plane, A'B'C'D ', and the line-of-sight transformation parameter is used as a perspective transformation parameter. The view angle θ is set, the map data included in the trapezoidal area ABCD on the xy plane is converted into the display coordinates on the display plane by perspective conversion, and the road display screen is generated.

Thus, the portable navigation device 1
The tilt sensor 12 is attached to the display device 11, the tilt angle α ° of the display device 11 is measured, and the current position G and the azimuth angle are measured by the GPS receiving device 13 and the like. Here, the viewpoint position calculation unit 16 provides the virtual viewpoint position P on the vertical line of the display screen from the inclination angle α ° of the display device 11, and then the perspective conversion road screen generation unit 17 records it in the CD-ROM device 14 or the like. The map data corresponding to the current position G that has been displayed is read out, and perspective transformation is performed with the virtual viewpoint position P having this height h as the viewpoint. As a result, when the display device 11 is held horizontally, as shown in FIG. 6, since the virtual viewpoint position is on the vertical line of the ground surface, the display device 11 displays a top view of the road map.

On the other hand, when the display device 11 is tilted, as shown in FIG. 7, by automatically switching to the bird's-eye view display according to the tilt angle, the operator is conscious of switching the display. Without doing so, a display format suitable for the purpose of the operator is selected. In addition, when the operator tilts the display device 11, an easy-to-see road image can be displayed according to the operation, so that the screen display can be automatically switched according to the operator's viewpoint. Further, in the first embodiment, the operator can switch between the top view and the bird's-eye view displayed on the display device 11 by an intuitive and simple operation without being aware of the operation as in the conventional case.

(Second Embodiment) A portable navigation device 1 according to a second embodiment of the present invention can be applied to the system configuration shown in FIG. In the second embodiment, as shown in FIG. 5A, the viewpoint position calculation unit 16 sets the virtual viewpoint position P on the extension line of the downward looking angle θ behind the current position G and the direction H. Set. The altitude h of the virtual viewpoint position P is set to a fixed position, for example, 360 m on the extension line of the line-of-sight direction. As a result, FIG.
As shown in (a), (b) and FIGS. 10 (a), (b),
The horizontal distance that can be displayed changes according to the change of the virtual viewpoint position P. In this way, with the automatic switching of the look-down angle θ, the vicinity of the current position is enlarged as it approaches the top view, and as shown in FIG. 10B, it is possible to easily recognize the facility or the intersection near the current position. it can.

(Third Embodiment) A portable navigation device 1 according to a third embodiment of the present invention can be applied to the system configuration shown in FIG. In the third embodiment, as shown in FIG. 8B, the viewpoint position calculation unit 16 sets the virtual viewpoint position P on the extension line of the downward looking angle θ behind the current position G and the direction H. Set. As for the virtual viewpoint position P, the distance L from the current position G is set to be constant and set to, for example, 1 km. As a result, as shown in FIGS.
As shown in FIGS. 12A and 12B, the horizontal distance and the altitude change according to the change of the virtual viewpoint position P. In this way, since the distance L to the current position is constant even if the look-down angle θ changes, the change in the scale is small, and it is possible to reduce the discomfort of the display screen due to the switching of the look-down angle θ.

(Fourth Embodiment) A portable navigation device 1 according to a fourth embodiment of the present invention can be applied to the system configuration shown in FIG. In the fourth embodiment, the viewpoint position calculation unit 16 sets the virtual viewpoint position P on the extension line of the downward looking angle θ behind the current position G and the direction H, as shown in FIG. 13. The virtual viewpoint position P has a constant horizontal distance from the current position G, for example, 750.
Set to m. As a result, FIG. 14 (a), (b), FIG.
As shown in 5 (a) and 5 (b), the altitude h changes according to the change of the virtual viewpoint position P.

In this way, even if the look-down angle θ changes, the change in the display range is small, and it is possible to obtain a map display in which the distant view is good as a whole. In the first to fourth embodiments, the tilt angle α ° measured by the tilt angle sensor 12 is measured.
The reference value k ° is compared with the reference value k °, and the case where the plan view and the bird's-eye view are switched and displayed based on the magnitude relationship obtained as a result has been described. The present invention is not limited to such comparison with the reference value k °. Without being limited, for example, by providing a hysteresis region in the reference value k °, the reference value k ° of the inclination angle α °
It is possible to prevent the display screen from oscillating due to the vibration in the vicinity. That is, the inclination angle α ° increases and the first reference value k
When it exceeds + 1 °, the display screen is switched to the bird's-eye view display, while the tilt angle α ° decreases and the second reference value k−1 °.
When the display screen is below the range, the display screen is switched to the plan view display, whereby the above-described oscillation of the display screen can be prevented.

Further, in the above-mentioned first to fourth embodiments,
Although the case where the tilt angle, the current position, and the azimuth angle are used as the parameters input to the viewpoint position calculation unit 16 has been described, the present invention is not limited to such parameters, and for example, a timer may be provided at regular intervals. Similarly, when the change amount of the current position of is used as the moving speed, the virtual viewpoint position can be configured to be a higher position on the extension line of the line-of-sight direction according to the moving speed.
As the moving speed increases, it is possible to visually recognize the object farther.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration of a portable navigation device according to first to fourth embodiments of the present invention.

FIG. 2 is an external view of a portable navigation device according to the present invention.

FIG. 3 is a flowchart for explaining calculation of a virtual viewpoint position and drawing of a map screen by perspective transformation of map data in a control device.

FIG. 4 is a diagram for explaining a relationship between a line-of-sight looking-down angle θ ° and an inclination angle α °.

FIG. 5 is a diagram showing the principle of bird's-eye view display.

FIG. 6 is a diagram showing an example of a road image when the inclination angle is small and the virtual viewpoint is on the current vertical line.

FIG. 7 is a diagram showing an example of a road image when the display device is tilted.

8A is a diagram showing that the altitude is set to be constant on an extension of the line of sight, and FIG. 8B is a diagram showing that the distance between the virtual viewpoint position and the current position is set to be constant.

FIG. 9 is a diagram showing how the horizontal distance that can be displayed changes as the altitude of the virtual viewpoint position changes.

FIG. 10 is a diagram showing how the horizontal distance that can be displayed changes as the altitude of the virtual viewpoint position changes.

FIG. 11 is a diagram showing how the horizontal viewpoint and altitude change as the virtual viewpoint position changes.

FIG. 12 is a diagram showing how the horizontal viewpoint and altitude change as the virtual viewpoint position changes.

FIG. 13 is a diagram showing that the virtual viewpoint position is set with a constant horizontal distance from the current position.

FIG. 14 is a diagram showing how the virtual viewpoint position changes and the altitude changes.

FIG. 15 is a diagram showing how the virtual viewpoint position changes and the altitude changes.

[Explanation of symbols]

1 Portable navigation device 11 Display 12 Tilt sensor 15 Control device 13 GPS receiver 14 CD-ROM device 16 Viewpoint position calculator 17 Perspective conversion road screen generation unit

Claims (5)

(57) [Claims] 1. A portable navigation device for converting map data into a top view or a bird's-eye view and displaying it on a display device, the device comprising: a tilt angle measuring means for measuring a tilt angle of the display device; and a current position and direction. A position measuring means for measuring an angle; a viewpoint position calculating means for calculating a virtual viewpoint position representing a position of a virtual viewpoint based on the measured tilt angle, current position and azimuth angle; and the calculated virtual viewpoint. Map drawing means for two-dimensionally converting map data according to the position and outputting the map data to the display device , wherein the viewpoint position calculating means continuously calculates the virtual viewpoint position according to the tilt angle of the display device.
A portable navigation device characterized by changing . Wherein said viewpoint position calculation means, according to claim 1, characterized in that the predetermined height of the virtual viewpoint position is changed on the extension line of sight direction corresponding to the inclination angle of the display device The portable navigation device described. 3. The viewpoint position calculating means sets the virtual viewpoint position, which is changed according to the tilt angle of the display device, at a position of a predetermined distance from the current position on the extension line of the line-of-sight direction. The portable navigation device according to claim 1 . 4. The viewpoint position calculation means sets the virtual viewpoint position, which is changed according to the tilt angle of the display device, at a position on the extension line of the line-of-sight direction that is different in altitude at a predetermined distance from the current position. claim wherein 1
The portable navigation device described. Wherein said viewpoint position calculation means, claims, characterized in that to determine horizontal or not based on the threshold value with hysteresis inclination angle of the measured by the inclination angle measuring means said display device 1 to claim 4
The portable navigation device according to item 1 .