Map displaying system and map displaying method

Details Map displaying system and map displaying method Map displaying system and map displaying method

2000-12-05

2003-04-01

Jankus, Almis R. (Department: 2671)

Computer graphics processing and selective visual display system

Display driving control circuitry

Controlling the condition of display elements

C345S440000, C345S215000, C345S215000

Reexamination Certificate

active

06542174

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a map displaying system for displaying map-data on a monitor, like a navigation system and so on.
BACKGROUND OF THE INVENITON
The navigation system is a system for detecting a user's standing position by GPS (Global Positioning System) or Self-supporting System, and displaying the standing position together with the surrounding map data on a monitor.
In the navigation system, the displaying method of map data has been improved variously because there is a necessity of comprehending instinctively the situation far way from the standing position. For instance, in the navigation system disclosed in Japanese Patent Laid-open Publication No. 7-220055, as a user is going away from the standing position, the map data is displayed scaling down, and a bird-eye view (a map described looking down on a landscape from the heights) is applied to such displayed map data, said bird-eye view prepared by the conversion processing of perspective projection described later.
The above navigation system, however, adopts 2-dimensional map data, so that the displayed map could be always a 2-dimensional bird-eye view. Accordingly, there was a problem that the user is hard to comprehend the standing position, as the displayed map does not agree with the actual landscape in case of undulating land.
Therefore, in the navigation system disclosed in Japanese Patent Laid-open Publication No. 10-207356, by making a use of 3-dimensional map data the distant place is displayed on a monitor as a 3-dimensional bird-eye view. The configuration will be described below according to FIG.
13
.
The 2-dimensional map data storage means
1
stores map data comprising position information and attribute information regarding roads, facilities, town blocks, landmark, and location name. The position information is represented by 2-dimensional coordinates corresponding to the latitude and the longitude.
The landform data storage means
2
stores altitude data of crossing points of the latitude and the longitude per specific degree (distance). That is to say, as shown in
FIG. 14
, each point represented by a white circle is equivalent to a crossing point of the latitude and the longitude located at a specific distance (degree). The black circles acquired by adding an altitude value to the crossing points are connected with each other, thereby a polyhedron (which is called “mesh-landform” hereinafter) is formed. The polyhedron is represented as the undulating conditions of the actual ground surface, that is, the landform (which will be described later).
When the standing position detecting means (the GPS, and so on) that is not shown in the drawings detects a user's standing position, the 2-dimensional bird-eye view preparing means
3
and the 3-dimensional bird-eye view preparing means
4
are activated and perform the conversion processing of the perspective projection shown in FIG.
15
.
In other words, the 2-dimensional bird-eye view preparing means
3
specifies the area (which is called “plane area” hereunder) to be displayed on the monitor as the 2-dimensional bird-eye view at first (in this step, the area to be displayed at the lower side of the monitor is specified), and fetches the map data corresponding to the plane area from the 2-dimensional map data storage means
1
. The map data thus fetched out is processed by the converting of the perspective projection, thereby the 2-dimensional bird-eye view data can be prepared.
On the other hand, the 3-dimensional map data preparing means
23
specifies the area (which is called “solid area” hereunder) to be displayed on the monitor as the 3-dimensional bird-eye view at first (in this step, the area to be displayed at the upper side of the monitor is specified), and fetches the map data corresponding to the solid area from the 2-dimensional map data storage means
1
while fetching the altitude data in the solid area from the landform data storage means
2
. After preparing the 3-dimensional map data as shown in
FIG. 16
in accordance with the map data and the altitude data fetched out as above, the 3-dimensional bird-eye view preparing means
4
prepares the 3-dimensional bird-eye view data by the conversion processing of the perspective projection on the display coordinate system.
After the 2-dimensional bird-eye view data and the 3-dimensional bird-eye view data are prepared as above, the display means
5
displays the 2-dimensional bird-eye view data at the lower side of the monitor and the 3-dimensional bird-eye view data at the upper side of the monitor (see FIG.
17
).
In the above description, the 2-dimensional map data is handled as one data including roads, facilities and etc., but when the road data should be main like a car-navigator, it is configured that road information are displayed being overlapped on the map information displayed as above.
Specifically, the 2-dimensional road data storage means
21
(which may be included in the 2-dimensional map data storage means) stores various information regarding roads as the 2-dimensional road data. The 2-dimensional road data comprises “point number information” for specifying each point composing a road (which is called “road component point” hereafter), “latitude and longitude information” for expressing the latitude and the longitude at which the road component point is located by the corresponding 2-dimensional coordinates (x-coordinate, y-coordinate), “road type information” for indicating the type of the road such as ROUTE X, “connection information” for expressing the road component points to be connected by the above-mentioned point number, and so on. And as shown in FIG.
18
(
a
), a Point
2
(x, y)=(
100
, −
100
), said point composing ROUTE
16
by being connected with a Point
3
, may be represented by the 2-dimensional road data, such as (
2
,
100
, −
100
, ROUTE
16
,
3
) [point number information, x-coordinate, y-coordinate, road number, point number information of the next connected point].
Here, providing that the map information should be converted to the 3-dimensional bird-eye view as described above, the problem is how to overlap the landform data with the road information.
As shown in
FIG. 13
, the 3-dimensional road data preparing means
22
first specifies an area to be displayed based on the standing position, and the 2-dimensional road data corresponding to the displayed area is fetched out from the 2-dimensional road data storage means
21
while the landform data corresponding to the displayed area is fetched out from the landform data storage means
2
. Moreover the 3-dimensional road data is prepared based on the 2-dimensional road data and the altitude data fetched out as above. The converting of the perspective projection is performed on the 3-dimensional road data.
Thereby, the ground surface image data and the 3-dimensional road image data are prepared. Such data are combined to the bird-eye view by the 3-dimensional bird-eye view preparing means
4
, and then handed to the display means
5
.
As a result, the monitor can display the image combining the ground surface image data and the 3-dimensional road image data even the solid data.
The navigation system disclosed in Japanese Patent Laid-open Publication No. 10-207356, however, is configured to prepare the 2-dimensional bird-eye view data based on only the 2-dimensional map data (which is not based on the altitude data). That is to say, although the actual altitude value is adopted as an altitude value of the solid area B, since 0 is used as the altitude value of the plane area, accordingly it causes a problem; the sudden altitude difference appears in the boundary between the 2-dimensional bird-eye view and the 3-dimensional bird-eye view, as shown in FIG.
17
.
And in the conventional navigation system, it is configured that the 3-dimensional road data is prepared only by connecting the road component points one after another with a straight line. Therefore, when there are the road component points dispersed from one mesh to another

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