JP3451699B2 - Navigation system with bird's eye view display function - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation system having a bird's-eye view display function that gives a visual effect of looking down a map in an oblique direction.

[0002]

2. Description of the Related Art A conventional navigation system has, for example, a configuration as shown in FIG. In this navigation system, an external storage device 1501 for storing various map information, a display reference point determination device 1502 for determining a reference point (display reference point) for determining a display area, and display scale information. Display scale input device 1503 for inputting the
1, display reference point determination device 1502, display scale input device 1
An arithmetic processing unit 1504 for inputting information from 503 to execute a predetermined arithmetic processing and an image display unit 1505 for displaying the arithmetic processing result of the arithmetic processing unit 1504.

Further, when the arithmetic processing unit 1504 is decomposed by function, an internal storage unit 1 for holding map information is provided.
504-2, and a data access unit 1504-1 that selects a portion required for the current display from the map information stored in the external storage device 1501 based on the display reference point and the display scale and loads the internal storage unit 1504-2. , Image data output unit 1504-3 which creates image data from the map information according to the scale information given by the display scale input device 1503 and outputs the image data to the image display device 1505.

Next, the operation will be described. In the external storage device 1501, map information is divided and stored for each fixed division area (see FIG. 5). This fixed section is, for example, 10 km divided by a straight line parallel to the longitude or latitude.
It is a square divided area on all sides. Hereinafter, this fixed square divided area will be referred to as a mesh.

The area on the map to be displayed is, for example,
It is limited to a certain range around the current position of the host vehicle.
The point that serves as a reference for determining the display area, such as the vehicle position, will be referred to as a display reference point hereinafter. The data access unit 1504-1 of the arithmetic processing device 1504 selects a mesh required for display from the external storage device 1501 according to the display reference point and the display scale.

FIG. 16 is a flow chart showing the processing operation of the navigation system shown in FIG. 15. First, the data access section 1504-1 sets the display reference point (CX, CY) by the display reference point determination device 1502. Then, the display scale input device 1503 sets the display scale (K) (S1602). Next, the display reference point determination device 1502 and the display scale input device 1
According to the output from 503, the area on the map to be displayed is calculated backward (S1603). Image display device 1505
If the display size is horizontal DX, vertical DY, the display scale is K, and the display reference point (CX, CY) is the center of the screen, the display target area is abscissa x and ordinate y, It is represented by the number 1. Here, the display area is always a rectangular area similar to the screen of the image display device 1505.

[0007]

[Equation 1]

Next, the minimum number of meshes covering the display target area is selected and determined (S1604). If the upper and lower limits of the abscissa and the upper and lower limits of the ordinate of the display target area defined by the above equation 1 are X1, X2, Y1, and Y2, respectively, and the mesh grid points are represented by (Xn, Ym),
In the case of Equation 2 below, the required mesh is a closed region [Xn, X
(n + i) × [Ym, Ym + j], i × j.

[0009]

[Equation 2]

Next, it is judged whether or not the information of each selected mesh has already been taken in (exists) in the internal storage unit 1504-2 (S1605), and the internal storage unit 1504.
-2, when it is determined that the mesh does not exist, only the map information of the mesh that does not exist in the corresponding internal storage unit 1504-2 is fetched (S1606).

On the contrary, when it is judged that the file exists in the internal storage unit 1504-2, or in the above step S1606.
After the end of the processing, the image data output unit 1504-3 performs similarity conversion on each map information on the internal storage unit 1504-2 according to the display scale input from the display scale input device 1503, and the graphic data Is output to the image display device 1505 (1607). After that, it is determined whether or not the series of processing is completed (S1608), and when it is determined that the series of processing is completed, the processing is completed. On the contrary, if it is determined that the processing is not completed, the process returns to step S1601 and the same processing is repeated. Through the above processing operations, this navigation system can output a map image of the ground looking down vertically from directly above the display reference point to the image display device 1505.

[0012]

However, in such a conventional navigation system,
In a wide area display with a high scale (small K), the map figure is compressed, making it difficult to read map information near the display reference point. On the contrary, in a magnified display with a low scale (large K) Since the display area is narrow, it is not possible to see information over a wide area such as recommended routes as a whole.
As a result, the user has to switch between the wide area display and the enlarged display as needed, which causes a problem of poor operability.

At that time, in the conventional navigation system, the display target area on the map, which is always a rectangle similar to the screen, becomes a trapezoidal area in the bird's-eye view display function. If you try to realize the bird's eye view display function with this configuration, a new problem that the selection of the mesh on the external storage device necessary for display becomes complicated and the processing time of the screen update accompanying the movement of the display reference point becomes long Occurs.

The present invention has been made in view of the above, and the map information in the vicinity of the display reference point can be enlarged and viewed by the bird's-eye view display function which gives a visual effect of looking down the map from an angle. A first object is to display a distant area so that the entire wide area information can be grasped, reduce the frequency of display switching during driving, and improve operability.

The present invention has been made in view of the above, and it is a first object of the present invention to simplify the mesh selection procedure of the external storage device and shorten the processing time of the screen update accompanying the movement of the display reference point. The purpose is 2.

[0016]

In order to achieve the above object, a navigation system with a bird's-eye view display function according to a first aspect of the present invention is such that an integral multiple of one side length is a circumscribed circle of a display target area.
External storage means for storing map information divided into square divided areas (mesh) set to have the same diameter, display reference point determination means for determining display reference points on the map, and the external storage means And arithmetic processing means for performing arithmetic processing necessary for bird's-eye view display based on information from the display reference point determining means, and image display means for displaying map information which is a calculation result by the arithmetic processing means. .

Further, in the navigation system with a bird's-eye view display function according to claim 2, an integer multiple of one side length is a display target area.
An external storage means for storing map information divided into square divided areas (mesh) in which the diameters of the circumscribed circles of the area are set to be equal, and a display reference point determining means for determining a display reference point on the map , A display parameter input means for inputting a viewing angle and other display parameters and arbitrarily changing the values of the display parameters, and information from the external storage means and the display reference point determining means and the display parameter input means. It is provided with arithmetic processing means for performing arithmetic processing necessary for bird's-eye view display based on the display parameters and image display means for displaying map information which is the arithmetic result by the arithmetic processing means.

In the bird's-eye view display function-equipped navigation system according to claim 3, the arithmetic processing means determines the viewpoint position and the display target area based on the information from the display reference point determining means. Decision means,
Data access means for accessing map information stored in the external storage means, internal storage means having a predetermined storage capacity for storing information accessed by the data access means, and stored in the internal storage means The map information is converted into coordinate information based on the information determined by the viewpoint position / display target area determination means, and the graphic data coordinate conversion means for generating bird's-eye view data and the bird's-eye view data generated by the graphic data coordinate conversion means. And image data output means for outputting to the image display means.

[0019]

In the bird's-eye view display function-equipped navigation system according to a fourth aspect of the present invention, the value of the integral multiple is preset according to the storage capacity of the internal storage means.

Further, in the navigation system with a bird's-eye view display function according to a fifth aspect, when the arithmetic processing means updates the display image of the image display means according to the movement of the display reference point, the viewpoint position / display target is displayed. By determining the mesh of the external storage means corresponding to the display area determined by the area determination means based on the center coordinates of the circumscribed circle, data access to the external storage means is reduced.

Further, in the bird's-eye view display function-equipped navigation system according to the sixth aspect , the arithmetic processing means stepwisely displays the image display means in accordance with the degree of detail and the distance from the viewpoint which are predetermined in each map information. The map is displayed on.

Further, in the navigation system with a bird's-eye view display function according to claim 7, an integer multiple of one side length is a display target area.
An external storage means for storing map information divided into square divided areas (mesh) in which the diameters of the circumscribed circles of the area are set to be equal, and a display reference point determining means for determining a display reference point on the map , An arithmetic processing means for performing arithmetic processing necessary for bird's-eye view display based on information from the external storage means and the display reference point determining means, the arithmetic processing means being on the screen of the image display means. The map information is displayed in a range limited by the pseudo horizon, and information other than the map information is displayed outside the map information display range. Further, in the navigation system with a bird's-eye view display function according to claim 8, the arithmetic processing means comprises:
Pseudo sky as information displayed outside the map information display range,
At least one of the destination direction and the current time is displayed.

[0024]

The navigation system with a bird's-eye view display function according to the present invention (claim 1) is a square divisional area (mesh
The map information that is divided for each image is processed according to the display reference points on the map, and the map information that is the calculation result is displayed. Both detailed information and wide area information can be grasped, and the frequency of display switching is reduced, improving operability. Furthermore, one side of the square division area (mesh)
Make the diameter of the circumscribed circle of the display area equal to an integer multiple of the length
Therefore, it is easy to access the map information in the external storage means.
Becomes

A navigation system with a bird's-eye view display function according to the present invention (claim 2) is a square partition area (mesh).
The map information divided by each is subjected to the calculation processing necessary for the bird's-eye view display based on the display reference point on the map and the display angle and other display parameters, and the map information as the calculation result is displayed. The field of view / viewpoint position can be freely selected according to the user's purpose and preference. In addition, the square compartment
Outside the display target area and an integral multiple of the side length of the area (mesh)
Since the diameters of the tangent circles are the same, map information in the external storage
Will be easier to access.

The navigation system with a bird's-eye view display function according to the present invention (claim 3) determines the viewpoint position and the display target area for the arithmetic processing by the arithmetic processing means, and accesses the map information stored in the external storage means. Then, the accessed information is stored, the stored map information is subjected to coordinate conversion based on the determined viewpoint position and display target area, bird's-eye view data is generated, and the generated bird's-eye view data is displayed on the image display means. Since it is output, the values of the parameters required for mesh selection on the external storage means can be easily obtained.

[0027]

In the navigation system with a bird's-eye view display function according to the present invention (claim 4) , since an integer multiple value is set in advance according to the storage capacity of the internal storage means, the hardware on a given hardware For constraints, this can be used as effectively as possible, and processing time is shortened.

A navigation system with a bird's-eye view display function according to the present invention (claim 5) , when updating a display image according to the movement of a display reference point, displays the display area determined by the viewpoint position / display target area determining means. By determining the mesh of the external storage means based on the center coordinates of the circumscribing circle, data access to the external storage means is reduced, so that the processing time can be shortened.

The navigation system with a bird's-eye view display function according to the present invention (claim 6) displays the map stepwise according to the degree of detail and the distance from the viewpoint, which is set in advance in each map information, so that the information readability is improved. Improve.

In the navigation system with a bird's-eye view display function according to the present invention (claims 7 and 8), the pseudo horizon is described on the screen of the image display means, the map information is displayed in a range limited by the pseudo horizon, and the map is displayed. Information other than map information, such as pseudo sky, destination direction, and current time, is displayed outside the information display range, so that the visual effect as a bird's-eye view is emphasized and more information is supplied to the user. be able to. In addition, one side length of the square division area (mesh)
To make the diameter of the circumscribed circle of the display area equal to an integer multiple
Makes it easy to access map information in external storage.
Become.

[0032]

【Example】

[First Embodiment] An embodiment of a navigation system with a bird's-eye view display function according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a navigation system with a bird's-eye view display function according to the present invention. In the figure, an external storage device 101 (external storage means in claims) for storing map information and a map Display reference point determination device 102 (display reference point determination means in the claims) for determining the display reference point, and various calculation processes based on information input from the external storage device 101 and the display reference point determination device 102. It comprises an arithmetic processing unit 103 (an arithmetic processing unit in the scope of claims) to be executed, and an image display unit 104 (an image display unit in the scope of claims) for displaying map information which is an arithmetic processing result by the arithmetic processing unit 103. Has been done.

Further, the arithmetic processing unit 103 includes a viewpoint position / display target area determining unit 103-1 (viewpoint position / display target area determining means) for determining a viewpoint position and a display target area, and the external unit. A data access unit 103-2 (data access unit in claims) for performing data access with the storage device 101, and an internal storage unit 103-3 for storing information input via the data access unit 103-2 (claim) (Internal storage unit in the range), the viewpoint position / display target area determination unit 103-1 and the graphic data coordinate conversion unit 103-4 that performs coordinate conversion of graphic data based on information from the internal storage unit 103-3. (Graphic data coordinate conversion means), and the graphic data coordinate-converted by the graphic data coordinate conversion unit 103-4 is displayed on the image display device. And an image data output section 103-5 that outputs (image data output unit in the claims) relative to 104.

Next, the operation will be described. 2 is a flowchart showing the processing operation of the navigation system shown in FIG. 1. First, the viewpoint position / display target area determination unit 103-1 determines the line-of-sight depression angle and the viewpoint height from the given display parameters ( S201). These numerical values must satisfy the conditions necessary for simplifying the mesh selection procedure stored in the external storage device 101.
This necessary condition and the calculation method based on it will be described below.

In FIG. 6, the viewpoint is at a point (0,0, h) in the three-dimensional Cartesian coordinate system (x, y, z), and the azimuth + y
It is assumed that the user is looking down on the ground with a direction and a depression angle θ. When θ is larger than the half-viewing angle in the vertical direction (β shown in FIG. 6), the display target area is inside the isosceles trapezoid ABCD. Here, consider a circular region circumscribing the trapezoid ABCD. If the radius of the circumscribed circle is R and the diameter 2R is equal to the length of one side of one mesh, it is necessary to cover the circular area no matter how it moves on the map as shown in FIG. The maximum number of meshes is four, and the display target trapezoidal region inscribed in this circular region is sufficiently covered with the same mesh.

More generally, if the circumscribed circle diameter 2R is equal to N times the side length of one mesh (N is a natural number), the number of meshes required to cover this circular region is (N + 1) ² at most.
It is a sheet. Therefore, the necessary condition for simplifying the mesh selection procedure is to make the circumscribed diameter of the trapezoid, which is the display target area, equal to an integral multiple of the side length of the mesh. The multiple N is
It may be determined in advance according to the storage capacity of the internal storage unit 103-3. In FIG. 6, the half viewing angle in the horizontal direction is α, and the aspect ratio of the screen of the image display device is S. The half-viewing angle β in the vertical direction and the horizontal one-side projected angle γ at the upper and lower ends of the screen are calculated by the following formula 3.

[0037]

[Equation 3]

As a result, the coordinates of the four points A, B, C, D are (-W1, D1), (W1, D1), (W2, D2),
When (-W2, D2) is set, the following Expression 4 is obtained. Therefore, the y coordinate y0 of the center of the circumscribing circle and the radius R are expressed by the following equations 5 and 6. In addition, in order to simplify the notation in Equations 5, 6 and subsequent equations,
It is replaced with tan α≡A and tan θ≡t.

[0039]

[Equation 4]

[0040]

[Equation 5]

[0041]

[Equation 6]

If the circumscribed circle radius R, the horizontal viewing angle 2α, and the screen aspect ratio S are given as the display parameters, the relationship between the two unknown variables h and t is determined as shown in the above equation 6, but only this Since the value of the variable is not determined in, it is necessary to introduce more display parameters. As an example, in this embodiment, the actual size of the lower side of the display screen (the length of the line segment AB, that is, 2W1) is adopted. This is an index indicating the approximate display scale of the area closest to the viewpoint. When the calculation formula of W1 is described using the above-mentioned simple notation, the following formula 7 is obtained.

[0043]

[Equation 7]

Therefore, by substituting the display parameters R, A, S, and W1 into the following equation 8 from the above equations 6 and 7,
The real root of t such that t> SA (that is, θ> β) is obtained, and
Alternatively, the value of h is obtained by substituting it into equation 7.

[0045]

[Equation 8]

Here, an approximate solution method such as the Newton method may be used to obtain t, or an exact solution may be obtained. The real root of t> SA in the above formula 8 is the following formula 9
Then, the following expression 10 is obtained, and this is substituted into the above expression 7 to obtain h.

[0047]

[Equation 9]

[0048]

[Equation 10]

For example, one side length of the mesh is 10 km (assuming that the circumscribed circle diameter is equal to one side length, R = 5000).
m), the actual size of the lower side of the screen is 500 m (W1 = 250), the horizontal viewing angle is 40 ° (A = tan 20 °), and the screen length /
When the aspect ratio is 3/4 (S = 0.75), the above equations 9 and 1
When t is calculated from 0, t = 0.317896 (θ = 1
7.6 °), and substituting this into Equation 7 above, h = 38
Get 6.78m.

Returning to the flowchart shown in FIG. 2, the display reference points (CX, C) are displayed via the display reference point determining device 102.
Y) and the direction in which the line of sight (φ) are set (S20
2) Next, the viewpoint position / display target area determination unit 103-1
Determines the viewpoint position according to the display reference point output from the display reference point determination device 102 (S203). Examples of the display reference point determining device 102 include a vehicle position measuring device that measures the current position of the own vehicle by a GPS sensor or the like and outputs this as a display reference point, or a user input from a pre-registered registration point list. A registration point calling device that selects one and outputs it as a display reference point, a scroll displacement input device that adds a displacement determined by a user input to the previous display reference point and outputs it as a new display reference point, and the like can be considered.

In FIG. 8, the display reference points are points (CX, C
Y). The calculation method of the viewpoint position differs depending on where it is displayed on the screen, but here, as an example, it is assumed that it is displayed at a distance of the actual size DC from the lower side along the vertical center line of the screen. There are various possible ways to determine the direction in which the viewpoint is directed. Here, the output of the display reference point determination device 102 is + x together with the coordinates of the display reference point.
It shall be given by the angle φ from the direction. If the viewpoint position is (VX, VY, VZ), VX = CX− (DC + D1) cosφ and VY = CY− (DC + D1) sinφ are obtained from these parameters. Also, as already mentioned, regarding VZ,
VZ = h.

In the flowchart shown in FIG. 2, next, the data access unit 103-2 finds the center coordinates of the circumscribed circle (S204), and selects (N + 1) ² meshes required for screen display (S205). . Assuming that the center of the circumscribed circle of the display target area is (RX, RY), as shown in FIG. 8, RX = VX + y0cosφ and RY = VY + y0sinφ. Therefore, according to FIG. [X _n , X _{n + N + 1} ] × [Y _m ,
Y _{n + N + 1} ], which is (N + 1) ² .

[0053]

[Equation 11]

Next, the data access unit 103-2 determines that the information of each selected mesh has already been stored in the internal storage unit 103-3.
It is determined whether or not it has been taken into (existing in) (S2
06), if it is determined that the mesh information has not been imported, the corresponding mesh information is imported (S207). That is,
Map information is fetched only for meshes that are not in the internal storage unit 103-3. Thus, the internal storage unit 10 of the arithmetic processing unit 103
The map information of up to ² meshes (N + 1) is always held in 3-3.

When the map information in the internal storage unit 103-3 is decided, the graphic data coordinate conversion unit 103-4 executes coordinate conversion for each map information, and the image data output unit 103-5.
The converted data is output to (S208). The map information is, for example, a set of points in a three-dimensional space {(MXi, MYi, MZ
i) | i = 1, 2, ...} as internal storage unit 103-
3, and the figure data coordinate conversion unit 103-4
The image display device 10 by the procedure described below.
Two-dimensional coordinate value fixed to the screen of No. 4 {(SXi, SY
i) | i = 1, 2, ...

As shown in FIGS. 10A to 10D, first, the points (MXi, MYi, MZi) described by the map space coordinate system (x, y, z) form the two-dimensional screen coordinate system. Three
It is transformed into a point (EXi, EYi, EZi) in the spatial coordinate system (xe, ye, ze) enlarged in dimension. (Xe, y
e, ze) is a right-handed coordinate system in which the viewpoint is the origin, the right direction of the screen of the image display device 104 is + xe, and the upward direction is + ye. The relationship between the two points in both coordinate systems is given by Equation 12 below.

[0057]

[Equation 12]

The points thus obtained (EXi, EYi, E
Zi) is a perspective projection of this on the screen (SX
i, SYi) is obtained by similarity transformation. The distance DS from the viewpoint (origin) to the screen is given by DS = DX / (2tanα), where DX is the horizontal width of the screen and α is the horizontal half-viewing angle, and this is used as a point (SXi, SYi) Is
It is calculated by the following equation 13.

[0059]

[Equation 13]

Returning again to the flowchart shown in FIG. 2, finally, the image data output unit 103-5 executes processing such as clipping on the obtained screen coordinates (SXi, SYi), The image data is output to the image display device 104 (S209). After that, for each map information on the internal storage unit 103-3, the above step S20 is performed.
After repeating steps 8 and S209, it is determined whether or not the processing is completed (S210). When it is determined that the processing is not completed, the viewpoint position / display target area determination unit 103 in step S202 is performed. Returning to the process of -1, the viewpoint position is updated based on the new display reference point, and thereafter, mesh selection, updating of the internal storage unit 103-3 (if necessary), coordinate conversion and drawing are repeated.

[Second Embodiment] Next, a second embodiment will be described. The bird's-eye view display function-equipped navigation system according to the second embodiment has a display parameter input device 300 (display parameter input means in claims) for inputting various display parameters in the configuration of the first embodiment shown in FIG. Is a configuration in which is added. FIG. 4 is a flowchart showing the processing operation of the navigation system with a bird's eye view display function shown in FIG.
In the first embodiment, among the display parameters given as constants, the user can appropriately input the horizontal viewing angle 2α and the screen lower side actual size 2W1 via the display parameter input device 300 (S401). It is determined whether or not the value of the display parameter of has changed (S
402). As a result, when it is determined that the display parameter value has changed, the viewpoint position / display target area determination unit 103-1 recalculates the depression angle (θ) and the viewpoint height (h) (S403). At this time, in the second embodiment, the screen aspect ratio S is set to S = G · DY / DX (0 <G <1) with respect to the screen size length DY and width DX, and the map display range on the screen is Limit as shown in Fig. 11, put a pseudo horizon as the boundary line, and above it
Information such as the current time is to be displayed in the pseudo empty portion of.

Further, according to the second embodiment, the map display range of the display screen is divided into a plurality of areas, and step display processing is performed in which the degree of detail of the displayed map information is changed according to the distance from the viewpoint. For example, as shown in FIG. 11, the display range is divided into two, the upper part (distant view) is the schematic map display range, and the lower part (near view) is the detailed map display range. It is assumed that the individual map information stored in the external storage device 101 is given a level of detail in advance. For example, the degree of detail is 1 for major roads such as expressways and national roads, and the degree of detail is 2 for local roads and other small roads.
Only the roads with the level of detail 1 are displayed in the schematic map display range, and all roads are displayed in the detailed map display range regardless of the level of detail.

These pieces of map information may be stored and managed for each common mesh as in the previous embodiment, or may be stored in units of meshes having different sizes for each detail level ( Generally, the more detailed the data, the larger the amount, so set the mesh finely).
Here, in the latter case, it is assumed that a main road is stored for each mesh having a side length L1 and a detailed road is stored for each mesh having a side length L2 (where L1> L2, for example, L1). = 10 km, L2 = 2 km).

Again, in the flow chart shown in FIG. 4, after the depression angle / height is calculated, the display reference point determination device 102 sets the display reference point and the like (S404) and the viewpoint position is calculated (S405) in the above embodiment. It is executed in the same manner as 1. Here, the diameter 2R of the circumscribed circle is the length L1 of one side of the main road mesh.
Is a value predetermined so as to be equal to an integer N times. That is, R = N · L1 / 2 (for example, N = 1, l
If 1 = 10 km, then R = 5000 m).

Next, the data access unit 103-2 uses the circumscribed circle center (RX, RY) required for selecting the main road mesh.
At the same time, the center coordinates (rx, ry) of the small circle necessary for selecting the detailed road mesh are obtained (S406). Here, the diameter 2r of the small circle is a value predetermined so as to be equal to an integer M times the length L2 of one side of the detailed road mesh. That is, r = M · L2 / 2 (for example, M = 1, L2 = 2 km
Then, r = 1000 m).

In FIG. 12, considering a small circle having a center on the y-axis and passing through two points A and B and having a radius r, y of the center point is considered.
The coordinate y1 is represented by the following Expression 14.

[0067]

[Equation 14]

At this time, if the two points where the small circle intersects with the outline of the display target area are C'and D ', the trapezoid ABC'D' is
As long as the condition of 2r = M · L2 (M is a natural number) is satisfied, it is always sufficiently covered with (M + 1) ² detailed road meshes. If y1 is given by the above formula 14, the center coordinates of the small circle can be obtained by rx = VX + y1cosφ and ry = VY + y1sinφ.

In the flowchart shown in FIG. 4, next, the data access unit 103-2 indicates the external storage device 101.
Selection of the upper mesh is executed (S407). For the main road mesh, [X
_n , X _{n + N + 1} ] × [Y _m , Y _{n + N + 1} ] (N +
1) Select ² sheets. Similarly, for the detailed road mesh, [X _P , X _{p + M + 1} ] ×
(M + 1) ² meshes corresponding to [Y _q , Y _{q + M + 1} ] are selected.

[0070]

[Equation 15]

Further, the selected mesh and the internal storage unit 103-
The comparison with S3 (S408) and the import into the internal storage unit 103-3 (S409) are executed in the same manner as in the first embodiment. The internal storage unit 103-3 always stores (N + 1) ²
The schematic map information for one sheet and the detailed map information for (M + 1) ² sheets are held.

Next, when the map information on the internal storage unit 103-3 is decided, the graphic data coordinate conversion unit 103-4 responds to each map information (MXi, MYi, MZi) by the above-mentioned mathematical expression 1
2, DS = DX / (2 tan α), coordinate conversion is executed according to Equation 13, and the two-dimensional screen coordinates (S
Xi, SYi) is obtained (S410). Finally, the image data output unit 103-5 outputs this as image data to the image display device 104. At this time, the image data output unit 1
03-5 performs different clipping processing according to the degree of detail attached to each map information (S411). For example, for main road data with a detail level of 1,
Accordingly, only the data whose screen coordinates (SXi, SYi) satisfy the following expression 16 are targeted for display, and the data in the other areas are clipped.

[0073]

[Equation 16]

On the other hand, in the detailed road data having the degree of detail 2, the following expression 17 is set as the display target range. In Expression 17 below, F represents the y value (ordinate value) of the boundary line between the schematic map display range and the detailed map display range in FIG. 11 as a ratio to the y value of the pseudo horizon.

[0075]

[Equation 17]

In FIG. 12, the coordinates of the point C'are (W3,
D3), where M is the slope of the straight line BC ', the following equation 1
8 and the number 19 are obtained.

[0077]

[Equation 18]

[0078]

[Formula 19]

By solving this, the following formula 20 is obtained.

[0080]

[Equation 20]

Further, according to FIG. 13, the above-mentioned F can be obtained by the following equation 21.

[0082]

[Equation 21]

Using the above numerical example, and further assuming that the small circle is covered with four detailed road meshes of 2 km on each side, r =
If it is set to 1000, F = 0.4846, therefore, when displaying the detailed road, clipping may be performed at 48.5% from the center to the upper side of the map display range.

If the output of all the image data has been completed and the map display processing is to be continued, the processing (step S401) is returned to the viewpoint position / display target area determination unit 103 (S412) to update the display parameters. Repeat the process from the check.

In the second embodiment, the degree of detail of the road information and the division of the display range associated therewith have been described as two stages, but the same can be done in the case of an arbitrary number of stages. Further, FIG. 14 shows an example of the bird's-eye view display screen obtained in the second embodiment.
A detailed road is displayed in the detailed map display range, but is clipped out in the schematic map display range. Also ,
A triangular mark indicating the direction of the destination is displayed in the pseudo sky part above the pseudo horizon as a boundary line .

[0086]

As described above, according to the navigation system with a bird's-eye view display function (Claim 1) according to the present invention, the map information divided for each square section area (mesh) is displayed on the map. Since the calculation processing necessary for the bird's-eye view display is performed based on the reference point and the map information which is the calculation result is displayed, it is possible to grasp both the detailed information near the display reference point and the entire wide area information by the bird's-eye view display, and The display switching frequency can be reduced and operability can be improved. In addition, the square section area (mesh)
Make the diameter of the circumscribed circle of the display target area equal to an integer multiple of one side length
Therefore, access to the map information in the external storage means
It will be easy.

[0087] Further, according to the bird's-eye view display function with a navigation system according to the present invention (Claim 2), square-gu
The map information divided for each image area (mesh) is processed based on the display reference point on the map, the viewing angle, and other display parameters, and the necessary map processing is performed to display the bird's-eye view. Therefore, the visual field / viewpoint position can be freely selected according to the user's use and preference. In addition, one side length adjustment of the square division area (mesh)
To make the diameter of the circumscribed circle of the display area equal to several times,
Easy access to map information in external storage
It

Further, according to the navigation system with a bird's-eye view display function according to the present invention (claim 3), the viewpoint position and the display target area are determined for the arithmetic processing by the arithmetic processing means and are stored in the external storage means. The map information is accessed, the accessed information is stored, the stored map information is subjected to coordinate conversion based on the determined viewpoint position and display target area, bird's-eye view data is generated, and the generated bird's-eye view data is generated. Since the data is output to the image display means, the values of the parameters required for mesh selection on the external storage means can be easily obtained.

[0089]

Further, according to the navigation system with a bird's-eye view display function according to the present invention (claim 4) , since an integer multiple value is set in advance according to the storage capacity of the internal storage means, it is possible to use a given hardware. For the constraints on the wear,
This can be used as effectively as possible.

Further, according to the navigation system with a bird's-eye view display function according to the present invention (claim 5) , when the display image is updated according to the movement of the display reference point, the external storage means for covering the display area on the map is displayed. By determining the mesh No. based on the center coordinates of the circumscribing circle, the data access to the external storage means is reduced, so that the processing time can be shortened.

Further, according to the navigation system with a bird's-eye view display function according to the present invention (claim 6) , the map is displayed step by step in accordance with the degree of detail and the distance from the viewpoint which are set in advance in the individual map information. Therefore, information readability can be improved.

Further, according to the navigation system with a bird's-eye view display function according to the present invention (claims 7 and 8), the pseudo horizon is described on the screen of the image display means, and the map information is displayed in the range limited by the pseudo horizon. Display and display information other than map information outside the map information display range, such as sky, current time,
Since the mark indicating the destination direction is displayed, the visual effect as a bird's-eye view can be emphasized and more information can be supplied to the user. In addition, the square section area (me
) And the diameter of the circumscribed circle of the display area
Are equal to each other.
Access is easy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a first embodiment according to the present invention.

FIG. 2 is a flowchart showing a processing operation of the navigation system shown in FIG.

FIG. 3 is a block diagram showing a schematic configuration of a second embodiment according to the present invention.

FIG. 4 is a flowchart showing a processing operation of the navigation system shown in FIG.

FIG. 5 is an explanatory diagram showing a storage form of map information in an external storage device.

FIG. 6 is an explanatory diagram showing a relationship between a viewpoint position, a display screen, and a display target area.

FIG. 7 is an explanatory diagram showing a state in which the display target area and the circumscribing circle move on the map.

FIG. 8 is an explanatory diagram showing a positional relationship between a viewpoint, a display reference point, and a center of a circumscribed circle.

FIG. 9 is an explanatory diagram showing a method of selecting a required mesh from the center of a circumscribed circle.

FIG. 10 is an explanatory diagram showing a coordinate conversion method of map information.

FIG. 11 is an explanatory diagram showing limitation / division of a map display range and a pseudo horizon.

FIG. 12 is an explanatory diagram showing a relationship between a display target area, a circumscribed circle, and a small circle.

FIG. 13 is an explanatory diagram showing positions of division boundaries of the map display range.

FIG. 14 is an explanatory diagram showing an example of a bird's-eye view display screen according to the present invention.

FIG. 15 is a block diagram showing a schematic configuration of a conventional navigation system.

16 is a flowchart showing a processing operation of the navigation system shown in FIG.

[Explanation of symbols]

101 external storage device 102 display reference point determination device 103 arithmetic processing unit 103-1 Viewpoint position / display target area determination unit 103-2 Data access unit 103-3 Internal storage unit 103-4 graphic data coordinate conversion unit 103-5 Image data output section 104 image display device 300 Display parameter input device

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-2-244188 (JP, A) JP-A-1-263688 (JP, A) JP-A-4-319985 (JP, A) JP-A-6- 301897 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G06T 11/60 G06T 17/50 G01C 21/00 G08G 1/0969 G09B 29/00-29/10

Claims (8)

(57) [Claims] 1. An external storage means for storing map information divided for each square section area (mesh) in which an integral multiple of one side length is set so that the circumscribed circles of the display target area have the same diameter, and a map. The display reference point determining means for determining the display reference point above, the arithmetic processing means for performing arithmetic processing necessary for bird's-eye view display based on the information from the external storage means and the display reference point determining means, and the arithmetic processing means. A navigation system with a bird's-eye view display function, comprising: an image display means for displaying map information as a calculation result. 2. An external storage means for storing map information divided for each square section area (mesh) in which an integral multiple of one side length is set so that the circumscribed circles of the display target area have the same diameter, and a map. Display reference point determining means for determining the above display reference point, display parameter inputting means for inputting a viewing angle and other display parameters to arbitrarily change the value of the display parameter, the external storage means and the display reference Arithmetic processing means for performing arithmetic processing necessary for bird's-eye view display based on information from the point determination means and display parameters input by the display parameter input means, and image display for displaying map information which is the calculation result by the arithmetic processing means. A navigation system with a bird's-eye view display function, comprising: 3. The calculation processing means is stored in the external storage means, and the viewpoint position / display target area determining means for determining the viewpoint position and the display target area based on the information from the display reference point determining means. Data access means for accessing map information, internal storage means having a predetermined storage capacity for storing information accessed by the data access means, and map information stored in the internal storage means for the viewpoint position / display Graphic data coordinate conversion means for performing coordinate conversion based on the information determined by the target area determination means to generate bird's-eye view data, and image data for outputting the bird's-eye view data generated by the graphic data coordinate conversion means to the image display means. The navigation system with a bird's-eye view display function according to claim 1 or 2, wherein the navigation system comprises an output means. 4. The navigation system with a bird's-eye view display function according to claim 1, wherein the value of the integral multiple is preset according to the storage capacity of the internal storage means. 5. The arithmetic processing means, when updating the display image of the image display means according to the movement of the display reference point, corresponds to the display area determined by the viewpoint position / display target area determination means. By determining the mesh of the external storage means based on the center coordinates of the circumscribed circle,
The navigation system with a bird's-eye view display function according to claim 1 or 2, wherein data access to the external storage means is reduced. 6. The arithmetic processing means displays the map on the image display means step by step according to the degree of detail and the distance from the viewpoint which are set in advance in each piece of map information. Or the navigation system with the bird's eye view display function described in 2. 7. An integral multiple of one side length is a circumscribed circle of a display target area.
External storage means for storing map information divided into square divided areas (mesh) set to have the same diameter, display reference point determination means for determining display reference points on the map, and the external storage Means and a calculation processing means for performing calculation processing necessary for bird's-eye view display based on information from the display reference point determination means, wherein the calculation processing means describes a pseudo horizon on the screen of the image display means, A navigation system with a bird's eye view display function, wherein map information is displayed in a range limited by the pseudo horizon and information other than map information is displayed outside the map information display range. 8. The arithmetic processing means displays at least one of a pseudo sky, a destination direction, and a current time as the information to be displayed outside the map information display range. Navigation system with bird's eye view display function.