JPH01263688A - Map display device for navigation - Google Patents

Abstract

PURPOSE:To display the relations between not only an adjacent area, but also a distant area and a target body at the same time by generating hierachic map data and selecting and displaying them according to the distance. CONSTITUTION:Data in a rough map (1st layer map) field 11, an intermediate- accuracy map (2nd layer map) field 12, and a precise-map (3rd layer map) field 13 are stored in a CD-ROM 20 as the map data to be utilized. Data are read out of the CD-ROM 22 through a CD-ROM driver 22 with an address signal and a read signal from a controller 21, processed properly according to a perspective system such as compression, expansion, and connection, and displayed on a CRT display 23 to give a prescribed display to the driver on a vehicle. The driver controls the display through an operation part 24. The direction of the vehicle from the external target is inputted periodically from an azimuth sensor 25 and a CPU corrects the direction according to the turning direction of the vehicle to store the current position on a RAM.

Description

DETAILED DESCRIPTION OF THE INVENTION In the present invention, map information is not stored as an image, but is stored in advance as digital information in a map database (for example, a compact disk fixed memory CD-ROM).
Store it in ROM). In other words, the map data is 2
If only dimensional information is displayed, the address is the coordinates (X, Z) of the distance vector R from the reference point (0, 0) such as the vehicle's current position or a specific position, and these are connected to form a line. Or express a surface and also display a road.

This display content (or further information such as the thickness or color of the display line depending on the road grade) may be combined as map data. It is also possible to store the map in a hierarchical structure, but in this case, the data that covers a wider area may be used as a combination address using coarser sampling points.

The above-mentioned fixedly stored map data is selectively read out on the principle of perspective drawing and displayed at points on the display screen. Several examples of this method are possible.

For perspective drawings, it is thought that perspective display, as if looking at the foreground through a window frame, best suits people's normal perceptual style, but any method that can provide fine and coarse display is considered to be suitable. However, since continuously displaying finer and coarser images as the distance increases may exceed the processing capacity of the microcomputer installed in the vehicle, in the preferred embodiment of the present invention, the display is performed by matching maps made into three-level data. think.

Another example is to approximate an arbitrary continuous function based on distance using a broken line. This greatly simplifies the process.

There are various types of perspective, but the one that is closest to actual vision is the planar perspective. However, in this method, the accuracy of the proximity position decreases rapidly with distance, so the spherical perspective method is better for displaying a regular planar map in the vicinity. Furthermore, in order to increase information on the traveling direction and information on the vicinity, a cylindrical-plane composite perspective system, which is an improved version of the spherical perspective system, is best, and this system is probably the closest to actual spatial recognition.

Upper side] U old [Elevated type Figure 1 shows the principle of the planar perspective method. In the figure, 1 is a perspective screen, and 2 is a planar projection map. Point P on map 2 from the current height yo from the map plane and f from the center of the screen
Point Q (x, z) where the line of sight intersects screen 1 when looking at
, , yo) are perspective points. Obviously x * =
x f /(f + z), and y.

It is expressed as = yoz/ (f + z), and the distance x and z from the vehicle position are determined by navigation signs (radio waves emitted from three places such as artificial satellites, or information from position notification devices left at major points on the road, etc.) As soon as we know from the difference between the map data (radio waves, etc.) and the map data, we can immediately find X,, y, and so on. The embodiment is a simplified method, and will be explained in detail later.

This method uses a spherical projection screen as the projection screen, and calculates the perspective point to the spherical screen when looking at a point P (x, z) on a planar map placed outside the spherical surface and in contact with the spherical surface from the center. It is represented by Q(θ, φ). However, θ is the angle measured from the Z axis to point P, and φ is the angle measured from the horizontal plane to point P. Between the coordinates of points P and Q, x = Rcot φeSin θ, z = Rc
There is a relationship of ot φ' cos θ (R is the radius of the sphere).

Figure 2 is a spherical perspective view of the regular lattice surface on the map, where φ=9
0", near θ=0 (that is, directly below and near the current position) is almost close to the actual map, and distant areas are compressed.

This method projects the points of the planar map 2 toward the center of the cylinder onto a screen l that combines a cylindrical surface with radius R and a plane, as shown in Figure 3. The screen obtained is as shown in FIG. 4, where a normal map is obtained as is in the vicinity of θ=0, and a plane perspective view is obtained in the distance. This display method is ideal.

(Description of Examples) Consider displaying the plane perspective view shown in FIG. 1 on a screen in a simplified manner. Other methods can be easily implemented in accordance with this method.

First, the map data that should be used is precise map data,
Prepare 3-layer data of intermediate precision map data and rough map data and record it on a CD-ROM.The reason for using such a layer is to avoid unnecessary high-precision information processing and to save money quickly and cheaply. This is to display the map on the display. This relationship is shown in FIG. In the figure, numeral 11 indicates one field of the first floor essential map, and for example, the whole country is divided into one field of 50 km square. The data is stored in one field of the ROM as rough ground data. 12 is the second
It shows one field of a key location, for example, one field is 5 km square, and is stored in one field of the ROM as intermediate precision map data. 13 indicates one field of the third Sui layer, for example, one field is 0.5 km square, and is stored in one field of the ROM as precise map data.

These data are retrieved by a device schematically shown in FIG. 6 and displayed on a CRT display. 20 converts, for example, nationwide hierarchical map fields 11, 12, and 13 into data 1. There is a data CD-ROM, and the information is transferred to the CD-ROM by the address signal, read signal, etc. from the control device 21.
The data is read out by the D-ROM driver 22, processed appropriately such as compression, expansion, and joining in accordance with the perspective drawing method shown in FIGS. give. The operation unit 24 is used by the driver to turn on and off the control device, and to display hierarchical maps 11, 12.
These are operation switches for displaying any one of the 13 images or for providing a transparent screen according to the present invention. The orientation sensor 25 periodically inputs the orientation of the vehicle from an external sign, and based on this input, the CPU makes corrections according to the direction change of the vehicle, and always records the current orientation in the RAM. Corrects the reading direction of the map data. A distance sensor 26 is also obtained periodically from an external landmark;
Using this as a reference, the CPU records the self-position in the RAM together with the azimuth signal, and the CPU automatically selects the map field to be read. Note that Ilo is input/output switching means, which switches input/output periodically at a high frequency using, for example, a clock pulse. Note that the display controller 27 performs calculations such as switching the display type and determining display coordinate points using the operation unit.

An example of a method of configuring a display screen using the planar perspective view method shown in FIG. 1 using hierarchical data is shown below.

When performing plane perspective as shown in Fig. 7, perspective screen 1 is 1
Precise map data is required for the 6th part, and becomes less necessary as the distance increases to 15.14.

If the information on the third floor essential map 13 of the map data is to be processed and displayed on the entire screen, it will be necessary to process a large amount of information. Therefore, in this embodiment, the screen is divided into three horizontal areas 14.
Divided into 15.16 and each map data 11.12
．． It consists of 13.

Referring to Figure 7, each map data of three layers is expressed by the relational expression of plane perspective x * = x f / (f + z)
, y, = yoz/ (f+z) (where, x and z are the values obtained by converting the coordinates of the difference between the vehicle's current position and the position on the hierarchical map data according to the vehicle's current orientation).1. As a result, each hierarchical map 11, 12, 13 becomes a trapezoid 1 on the display 14, 15, 16.
It will be displayed as part of 7.18.19.

Note that areas near the vanishing point that require a large amount of data are cut to reduce data. This correction calculation is performed by the display controller 27 in FIG. The trapezoid 18 obtained by calculation, for example, is as shown in FIG.

Here, X and Z are the original coordinate values. Note that if each hierarchical map data is displayed with actual coordinate values, areas 14, 15.
The alignment of the 16 seams occurs naturally. In addition, data calculations are based on seam spacing 2 = 0~Zl, Z1~Zz, Z2~Z
You only need to do this in 3.

According to this embodiment, the correction calculations for the horizontal areas 14, 15, 16 can be performed using a relatively small number of data, so that the entire calculation can be performed in a very short time. For example, place a vanishing point (Z =
If the OO) side is cut, correction calculations for each hierarchical map data are limited to within one field.

It will be obvious that other perspective drawing methods can be easily implemented using hierarchical map data.

(Function and Effect) According to this embodiment, map data is layered, selected according to distance, and displayed on the display screen, so information necessary for vehicle drivers is displayed close to real space recognition. This can be easily done with relatively little data processing.

4. N No. 3 □ Theory 0 Figure 1 is an explanatory diagram of the plane perspective diagram method, Figure 2 is an explanatory diagram of the spherical perspective diagram method, Figure 3 is an explanatory diagram of the cylindrical surface one-plane composite perspective diagram method, FIG. 4 is a diagram showing a display screen of the method shown in FIG. 3, FIG. 5 is a perspective view showing a hierarchical map used in the present invention, and FIG. FIG. 7 is a block diagram showing the map data display device, FIG. 7 is a diagram showing the operating principle of the device of the present invention, and FIG. 8 is a diagram showing the coordinates of the corners of the specific trapezoid in FIG. FIG.

Name of one agent: Motohiro Kurauchi 1.1-Hiroshi Kazama'') 5. Figure 1 Figure 2 e'=.

Figure 3 Figure 4 'e-.

Figure 8 Procedural amendment July 12, 1989 Commissioner of the Japan Patent Office Yoshi 1) Indication of the case of Takeshi Moon 1988 Patent Application No. 91621, title of invention Relationship with the case of person who amends a navigation map display device Patent Applicant name: Toshio Yamazaki

Claims (1)

[Claims] 1. Information is read from a map database converted into digital coordinates, and the accuracy of the map is reduced relative to the distance from the current position or specified position of the vehicle such as a car, and the information is continuously compressed on the display device. A navigation map display device configured to display a map. 2. A plurality of sets of map data means hierarchized from fine to coarse; a display means; 2. The map display device according to claim 1, wherein the farther the map data is, the coarser and wider the map data is displayed, and the boundary portions between the display areas of the map data of the different layers are displayed in alignment.