U.S. patent application number 09/774561 was filed with the patent office on 2001-08-09 for intersection display method, and map display unit and recording medium for realizing the method.
Invention is credited to Ata, Teruaki, Hamada, Hiroyuki, Sakamoto, Kiyomi, Yamashita, Atsushi.
Application Number | 20010012981 09/774561 |
Document ID | / |
Family ID | 18551335 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010012981 |
Kind Code |
A1 |
Yamashita, Atsushi ; et
al. |
August 9, 2001 |
Intersection display method, and map display unit and recording
medium for realizing the method
Abstract
On receipt of route information, map data in an area near the
route is read S11. One intersection existing on the route is
extracted from the read map data, and intersection-connected links
connected to the intersection are extracted S12. The road widths
from the center line to the right and left sides are specified for
the intersection-connected links based on attribute data such as
the actual road width of the intersection-connected links S13. New
lines are drawn for all the intersection-connected links by
translating the line representing the intersection-connected link
as the center line rightward and leftward by the specified road
widths, to determine right and left side lines of the
intersection-connected link S14. Based on the thus-generated
width-imparted intersection-connected links, an intersection shape
is generated S15. This processing is repeated for all the
intersections concerned S16. This makes it possible to generate and
display intersection shapes based on a road network map having a
degree of scale higher than a town map.
Inventors: |
Yamashita, Atsushi; (Osaka,
JP) ; Sakamoto, Kiyomi; (Ikoma, JP) ; Hamada,
Hiroyuki; (Yawata, JP) ; Ata, Teruaki; (Osaka,
JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
18551335 |
Appl. No.: |
09/774561 |
Filed: |
February 1, 2001 |
Current U.S.
Class: |
701/410 ;
340/995.1 |
Current CPC
Class: |
G01C 21/3626 20130101;
G05D 1/0278 20130101; G05D 1/0272 20130101; G05D 2201/0213
20130101; G05D 1/028 20130101; G05D 1/0274 20130101 |
Class at
Publication: |
701/211 ;
340/995; 701/208 |
International
Class: |
G01C 021/32 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 2, 2000 |
JP |
2000-25480 |
Claims
What is claimed is:
1. An intersection display method for generating and displaying an
intersection shape by use of map data including a road network, the
method comprising the steps of: reading from said map data an
intersection node representing an intersection and
intersection-connected links representing roads connected to the
intersection node, constituting the road network; generating an
intersection shape at the intersection node and width-imparted
intersection-connected links, based on said intersection node and
said intersection-connected links; and displaying said intersection
shape together with other information for guidance
notification.
2. The intersection display method according to claim 1, wherein
said step of generating an intersection shape comprises the steps
of: generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and determining
lines extending orthogonal to said intersection-connected links at
positions outside the cross points with respect to said
intersection node; and determining cross points between said lines
and said side lines, and connecting the cross points in the order
of said sorted intersection-connected links to form a polygon as
the intersection shape.
3. The intersection display method according to claim 1, wherein
said step of generating an intersection shape comprises the steps
of: generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and connecting
the cross points in the order of said sorted intersection-connected
links to form a polygon; and determining new points by shifting
said cross points as the vertexes of said polygon by a
predetermined distance along said side lines crossing at the
respective vertexes outward with respect to said intersection node,
and connecting the new points in the order of said sorted
intersection-connected links to form a new polygon as the
intersection shape.
4. The intersection display method according to claim 1, wherein
said step of generating an intersection shape comprises the steps
of: generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and connecting
the cross points in the order of said sorted intersection-connected
links to form a polygon; and generating a predetermined circle
including said polygon with said intersection node as a center, as
the intersection shape.
5. The intersection display method according to claim 1, wherein
said step of generating an intersection shape comprises the steps
of: generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and connecting
the cross points in the order of said sorted intersection-connected
links to form a polygon; and generating a predetermined circle
including said polygon with said intersection node as a center,
determining cross points between the circle and said side lines,
and connecting the cross points in the order of said sorted
intersection-connected links to form a new polygon as the
intersection shape.
6. The intersection display method according to claim 1, further
comprising, after the step of generating an intersection shape, the
steps of: processing the intersection-connected links, including
reading information on accessories of said intersection-connected
links from said map data, and generating shapes of the accessories
and determining the positions of the accessories in said
intersection-connected links with reference to said intersection
shape; and processing the intersection, including reading
information on accessories of said intersection node from said map
data, and generating shapes of the accessories and determining the
positions of the accessories in said intersection shape with
reference to said intersection shape, wherein said step of
processing the intersection-connected links includes deleting
portions of the accessories extending along roads (such as center
lines, lanes, side strips, and sidewalls) that overlap the
intersection shape.
7. The intersection display method according to claim 6, wherein,
when said map data includes information that two of said
intersection-connected links connected to the intersection are
major roads, said step of processing the intersection includes
connecting center lines and lanes belonging to the two major roads
among said deleted center lines and lanes belonging to the
intersection-connected links smoothly, to generate a center line
and lanes in the intersection shape.
8. The intersection display method according to claim 1, wherein
the step of generating an intersection shape relates to generation
of an intersection shape on a route from a departure point to a
destination or a stopover searched based on said map data, and the
step further comprises the steps of: generating a vehicle path
along a predetermined position on said width-imparted
intersection-connected links through which the route runs; and
deleting a portion of the vehicle path that overlaps said
intersection shape and connecting remainders of the vehicle path in
the areas other than the intersection shape separated by the
deletion smoothly, to generate a vehicle path in said intersection
shape.
9. The intersection display method according to claim 1, wherein,
when said map data includes information on a stop line of said
intersection-connected link, said step of displaying the
intersection shape includes generating the distance from the
position of a vehicle to the stop line as the distance from the
position of the vehicle to a coming intersection, in the generation
of notification information for guidance of the vehicle based on
said map data, said intersection shape, and the route from a
departure point to a destination or a stopover searched based on
said map data.
10. A map display unit for displaying a map for guidance,
comprising: a map data storage part for storing map data including
a road network; a route search part for searching a route from a
departure point to a destination or a stopover based on said map
data; a vehicle position detection part for detecting the position
of a vehicle mounting the unit on said map data; an intersection
shape generation part for reading an intersection node representing
an intersection and intersection-connected links representing roads
connected to the intersection node constituting said road network,
and generating width-imparted intersection-connected links and an
intersection shape at the intersection node based on the
intersection node and the intersection-connected links; a guidance
part for generating notification information for guidance of the
vehicle based on said map data, said intersection shape, and said
route searched; and an output part for outputting said notification
information via map display or any other medium.
11. The map display unit according to claim 10, wherein said
intersection shape generation part performs the operation of:
generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of a road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points
between inner ones of said side lines for every two adjacent ones
of said width-imparted intersection-connected links, and
determining lines extending orthogonal to said
intersection-connected links at positions outside the cross points
with respect to said intersection node; and determining cross
points between said lines and said side lines, and connecting the
cross points in the order of said sorted intersection-connected
links to form a polygon as the intersection shape.
12. The map display unit according to claim 10, wherein said
intersection shape generation part performs the operation of:
generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and connecting
the cross points in the order of said sorted intersection-connected
links to form a polygon; and determining new points by shifting
said cross points as the vertexes of said polygon by a
predetermined distance along said side lines crossing at the
respective vertexes outward with respect to said intersection node,
and connecting the new points in the order of said sorted
intersection-connected links to form a new polygon as the
intersection shape.
13. The map display unit according to claim 10, wherein said
intersection shape generation part performs the operation of:
generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and connecting
the cross points in the order of said sorted intersection-connected
links to form a polygon; and generating a predetermined circle
including said polygon with said intersection node as a center, as
the intersection shape.
14. The map display unit according to claim 10, wherein said
intersection shape generation part performs the operation of:
generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and connecting
the cross points in the order of said sorted intersection-connected
links to form a polygon; and generating a predetermined circle
including said polygon with said intersection node as a center,
determining cross points between the circle and said side lines,
and connecting the cross points in the order of said sorted
intersection-connected links to form a new polygon as the
intersection shape.
15. The map display unit according to claim 10, wherein, said
intersection shape generation part further performs the operation
of: reading information on accessories of said
intersection-connected links from said map data, and generating
shapes of the accessories and determining the positions of the
accessories in said intersection-connected links with reference to
said intersection shape, after the generation of the intersection
shape; reading information on accessories of said intersection node
from said map data, and generating shapes of the accessories and
determining the positions of the accessories in said intersection
shape with reference to said intersection shape, after the
generation of the intersection shape; and deleting portions of the
accessories extending along roads (such as center lines, lanes,
side strips, and sidewalls) that overlap the intersection
shape.
16. The map display unit according to claim 15, wherein, when said
map data includes information that two of said
intersection-connected links connected to the intersection are
major roads, said intersection shape generation part connects
center lines and lanes belonging to the two major roads among said
deleted center lines and lanes belonging to the
intersection-connected links smoothly, to generate a center line
and lanes in the intersection shape.
17. The map display unit according to claim 10, wherein said
intersection shape generation part generates an intersection shape
on a route from a departure point to a destination or a stopover
searched based on said map data, and further performs the operation
of: generating a vehicle path along a predetermined position on
said width-imparted intersection-connected links through which the
route runs; and deleting a portion of the vehicle path that
overlaps said intersection shape and connecting remainders of the
vehicle path in the areas other than the intersection shape
separated by the deletion smoothly, to generate a vehicle path in
said intersection shape.
18. The map display unit according to claim 10, wherein, when said
map data includes information on a stop line of said
intersection-connected link, said guidance part generates the
distance from the position of the vehicle to the stop line as the
distance from the position of the vehicle to a coming
intersection.
19. A recording medium containing an intersection display method
for generating and displaying an intersection shape by use of map
data including a road network recorded as a computer-executable
program, the program at least executing the steps of: reading from
said map data an intersection node representing an intersection and
intersection-connected links representing roads connected to the
intersection node, constituting the road network; generating an
intersection shape at the intersection node and width-imparted
intersection-connected links, based on said intersection node and
said intersection-connected links; and displaying said intersection
shape together with other information for guidance
notification.
20. The recording medium according to claim 19, wherein said step
of generating an intersection shape comprises the steps of:
generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and determining
lines extending orthogonal to said intersection-connected links at
positions outside the cross points with respect to said
intersection node; and determining cross points between said lines
and said side lines, and connecting the cross points in the order
of said sorted intersection-connected links to form a polygon as
the intersection shape.
21. The recording medium according to claim 19, wherein said step
of generating an intersection shape comprises the steps of:
generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and connecting
the cross points in the order of said sorted intersection-connected
links to form a polygon; and determining new points by shifting
said cross points as the vertexes of said polygon by a
predetermined distance along said side lines crossing at the
respective vertexes outward with respect to said intersection node,
and connecting the new points in the order of said sorted
intersection-connected links to form a new polygon as the
intersection shape.
22. The recording medium according to claim 19, wherein said step
of generating an intersection shape comprises the steps of:
generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and connecting
the cross points in the order of said sorted intersection-connected
links to form a polygon; and generating a predetermined circle
including said polygon with said intersection node as a center, as
the intersection shape.
23. The recording medium according to claim 19, wherein said step
of generating an intersection shape comprises the steps of:
generating a width-imparted intersection-connected link by
specifying a road width of each of said intersection-connected
links based on information associated with the
intersection-connected link, and drawing side lines representing
edges of the road on the right and left sides of said
intersection-connected link based on the specified road width;
sorting the positions of said intersection-connected links based on
the bearings at which the intersection-connected links are
connected to said intersection node; determining cross points each
between inner ones of said side lines of every two adjacent ones of
said width-imparted intersection-connected links, and connecting
the cross points in the order of said sorted intersection-connected
links to form a polygon; and generating a predetermined circle
including said polygon with said intersection node as a center,
determining cross points between the circle and said side lines,
and connecting the ross points in the order of said sorted
intersection-connected inks to form a new polygon as the
intersection shape.
24. The recording medium according to claim 19, wherein the program
further executes, after the step of generating an intersection
shape, the steps of: processing the intersection-connected links,
including reading information on accessories of said
intersection-connected links from said map data, and generating
shapes of the accessories and determining the positions of the
accessories in said intersection-connected links with reference to
said intersection shape; and processing the intersection, including
reading information on accessories of said intersection node from
said map data, and generating shapes of the accessories and
determining the positions of the accessories in said intersection
shape with reference to said intersection shape, wherein said step
of processing the intersection-connected links includes deleting
portions of the accessories extending along roads (such as center
lines, lanes, side strips, and sidewalls) that overlap the
intersection shape.
25. The recording medium according to claim 24, wherein, when said
map data includes information that two of said
intersection-connected links connected to the intersection are
major roads, said step of processing the intersection includes
connecting center lines and lanes belonging to the two major roads
among said deleted center lines and lanes belonging to the
intersection-connected links smoothly, to generate a center line
and lanes in the intersection shape.
26. The recording medium according to claim 19, wherein the step of
generating an intersection shape relates to generation of an
intersection shape on a route from a departure point to a
destination or a stopover searched based on said map data, and the
step further comprises the steps of: generating a vehicle path
along a predetermined position on said width-imparted
intersection-connected links through which the route runs; and
deleting a portion of the vehicle path that overlaps said
intersection shape and connecting remainders of the vehicle path in
the areas other than the intersection shape separated by the
deletion smoothly, to generate a vehicle path in said intersection
shape.
27. The recording medium according to claim 19, wherein, when said
map data includes information on a stop line of said
intersection-connected link, said step of displaying the
intersection shape includes generating the distance from the
position of a vehicle to the stop line as the distance from the
position of the vehicle to a coming intersection, in the generation
of notification information for guidance of the vehicle based on
said map data, said intersection shape, and the route from a
departure point to a destination or a stopover searched based on
said map data.
28. A data recording medium containing recorded computer-readable
data, the data comprising: data on an intersection node
representing an intersection constituting a road network; data on
intersection-connected links representing roads connected to said
intersection node constituting the road network; and data on an
intersection shape corresponding to said intersection node,
generated based on said intersection node and said
intersection-connected links.
29. The data recording medium according to claim 28, wherein said
intersection shapes is a polygon formed by: generating a
width-imparted intersection-connected link by specifying a road
width of each of said intersection-connected links based on
information associated with the intersection-connected link, and
drawing side lines representing edges of the road on the right and
left sides of said intersection-connected link based on the
specified road width; sorting the positions of said
intersection-connected links based on the bearings at which the
intersection-connected links are connected to said intersection
node; determining cross points between inner ones of said side
lines for every two adjacent ones of said width-imparted
intersection-connected links, and determining lines extending
orthogonal to said intersection-connected links at positions
outside the cross points with respect to said intersection node;
and determining cross points between said lines and said side
lines, and connecting the cross points in the order of said sorted
intersection-connected links.
30. The data recording medium according to claim 28, wherein said
intersection shape is a polygon formed by: generating a
width-imparted intersection-connected link by specifying a road
width of each of said intersection-connected links based on
information associated with the intersection-connected link, and
drawing side lines representing edges of the road on the right and
left sides of said intersection-connected link based on the
specified road width; sorting the positions of said
intersection-connected links based on the bearings at which the
intersection-connected links are connected to said intersection
node; determining cross points each between inner ones of said side
lines of every two adjacent ones of said width-imparted
intersection-connected links, and connecting the cross points in
the order of said sorted intersection-connected links to form a
provisional polygon; and determining new points by shifting said
cross points as the vertexes of the provisional polygon by a
predetermined distance along said side lines crossing at the
respective vertexes outward with respect to said intersection node,
and connecting the new points in the order of said sorted
intersection-connected links.
31. The data recording medium according to claim 28, wherein said
intersection shape is a predetermined circle formed by: generating
a width-imparted intersection-connected link by specifying a road
width of each of said intersection-connected links based on
information associated with the intersection-connected link, and
drawing side lines representing edges of the road on the right and
left sides of said intersection-connected link based on the
specified road width; sorting the positions of said
intersection-connected links based on the bearings at which the
intersection-connected links are connected to said intersection
node; determining cross points each between inner ones of said side
lines of every two adjacent ones of said width-imparted
intersection-connected links, and connecting the cross points in
the order of said sorted intersection-connected links; and
generating the predetermined circle including said polygon with
said intersection node as a center.
32. The data recording medium according to claim 28, wherein said
intersection shape is a polygon formed by: generating a
width-imparted intersection-connected link by specifying a road
width of each of said intersection-connected links based on
information associated with the intersection-connected link, and
drawing side lines representing edges of the road on the right and
left sides of said intersection-connected link based on the
specified road width; sorting the positions of said
intersection-connected links based on the bearings at which the
intersection-connected links are connected to said intersection
node; determining cross points each between inner ones of said side
lines of every two adjacent ones of said width-imparted
intersection-connected links, and connecting the cross points in
the order of said sorted intersection-connected links to form a
provisional polygon; and generating a predetermined circle
including said provisional polygon with said intersection node as a
center, determining cross points between the circle and said side
lines, and connecting the cross points in the order of said sorted
intersection-connected links.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an intersection display
method, and a map display unit and a recording medium for realizing
this method. More particularly, the present invention relates to a
method for displaying an intersection shape employed in map display
units represented by vehicle-mounted navigation systems and
portable navigation systems, a map display unit employing this
method, and a recording medium containing a computer program or
data for executing this method.
[0003] 2. Description of the Background Art
[0004] Initially, in map display units such as navigation systems,
a road network map using nodes and links to represent intersections
and roads respectively was generally displayed on a screen upon
request of the user.
[0005] In such a road network map, roads (links) were not provided
with their widths. Therefore, the user found difficulty in
intuitively understanding a node on the map as an intersection.
Moreover, this type of map failed to display detailed road
information, such as the number of lanes and lane regulations,
relating to actual intersections and junctions (hereinafter, these
are collectively called "intersections").
[0006] In recent years, in order to overcome the above problems,
there have been developed various navigation systems employing a
method for displaying a map provided with road widths. That is,
road links are displayed in the shape having widths corresponding
to the actual road widths, so as to present a map including roads
closer to the actual roads in shape. According to the conventional
method for displaying a map provided with road widths, road shapes
having widths corresponding to the actual road widths are generated
based on road links, and placed overlapping each other. In this
method, the overlap portion of all the width-imparted roads
connected to one node is considered as an intersection for
convenience.
[0007] As a conventional map capable of providing intersections for
convenience, usable is a town map constructed of geometries of
buildings and blocks. In such a town map, portions other than
buildings and blocks can be recognized as roads. Therefore, by
using a town map, an intersection can be displayed in a shape
considerably close to the actual shape.
[0008] The conventional method for displaying a map provided with
road widths described above has the following problems. This method
simply considers the overlap portion of width-imparted road links
as an intersection shape for convenience. That is, this method does
not generate an actual intersection shape. Therefore, the
intersection shape for convenience greatly differs from the actual
intersection shape in many cases.
[0009] In addition, in the conventional method for displaying a map
provided with road widths, since the actual intersection shape is
not recognized, it is very difficult to specify the positions at
which accessories in and around an intersection (crosswalks, stop
lines, an island in the center of a rotary, and the like) are to be
placed.
[0010] Moreover, in the conventional method for displaying a map
provided with road widths, a problem arises when a driving path is
to be displayed in an intersection along a route searched based on
the road network. That is, since the actual intersection shape is
not determined, a driving path can only be drawn as a path passing
through the node (intersection) of the original road network.
Therefore, a smooth driving path cannot be drawn for a right or
left turn at the intersection.
[0011] The conventional method using a town map for recognizing an
intersection shape has the following problem. It takes a huge
amount of time to collect nationwide detailed town map data. In
reality, therefore, town maps of only limited areas are collected.
If nationwide town map data is successfully collected, the
resultant data amount will be enormous. It is difficult to store
such nationwide town map data in a map display unit having a small
memory capacity, a map display unit that receives map data via
communications, and the like.
SUMMARY OF THE INVENTION
[0012] Therefore, an object of the present invention is to provide
an intersection display method for generating and displaying an
intersection shape by use of a road network map having a degree of
scale higher than a town map, and a map display unit and a
recording medium for realizing this method.
[0013] The present invention has the following features to attain
the object above.
[0014] A first aspect of the present invention is directed to an
intersection display method for generating and displaying an
intersection shape by use of map data including a road network. The
method includes the steps of:
[0015] reading from the map data an intersection node representing
an intersection and intersection-connected links representing roads
connected to the intersection node, constituting the road
network;
[0016] generating an intersection shape at the intersection node
and width-imparted intersection-connected links, based on the
intersection node and the intersection-connected links; and
[0017] displaying the intersection shape together with other
information for guidance notification.
[0018] As described above, in the first aspect, an intersection
shape is generated with reference to a road network included in map
data. This allows for display of an intersection shape closer to
the actual shape. In addition, the amount of map data required can
be smaller compared with the case of generating an intersection
shape using a town map.
[0019] Preferably, the step of generating an intersection shape
includes:
[0020] generating a width-imparted intersection-connected link by
specifying a road width of each of the intersection-connected links
based on information associated with the intersection-connected
link, and drawing side lines representing edges of the road on the
right and left sides of the intersection-connected link based on
the specified road width; and
[0021] sorting the positions of the intersection-connected links
based on the bearings at which the intersection-connected links are
connected to the intersection node.
[0022] Thereafter, the following technique may be adopted.
[0023] The technique includes: determining cross points each
between inner side lines of every two adjacent width-imparted
intersection-connected links, and determining lines extending
orthogonal to the intersection-connected links at positions outside
the cross points with respect to the intersection node; and
[0024] determining cross points between the lines and the side
lines, and connecting the cross points in the order of the sorted
intersection-connected links to form a polygon as the intersection
shape.
[0025] By the above technique, the width-imparted road links and
the lines defining the intersection shape cross at right angles.
Therefore, the vehicle stop position at the intersection is
explicitly determined, and the resultant intersection shape is
closer to the actual shape.
[0026] Alternatively, the technique may include: determining cross
points each between inner side lines of every two adjacent
width-imparted intersection-connected links, and connecting the
cross points in the order of the sorted intersection-connected
links to form a polygon; and
[0027] determining new points by shifting the cross points as the
vertexes of the polygon by a predetermined distance along the side
lines crossing at the respective vertexes outward with respect to
the intersection node, and connecting the new points in the order
of the sorted intersection-connected links to form a new polygon as
the intersection shape.
[0028] The overlap portion of the width-imparted road links itself
is not used as the intersection shape, but is expanded by shifting
the vertexes of the portion outward with respect to the
intersection node, to increase the number of corners of the
intersection shape. The resultant intersection shape is closer to
the actual shape.
[0029] Alternatively, the technique may include: determining cross
points each between inner side lines of every two adjacent
width-imparted intersection-connected links, and connecting the
cross points in the order of the sorted intersection-connected
links to form a polygon; and
[0030] generating a predetermined circle including the polygon with
the intersection node as a center, as the intersection shape.
[0031] This allows for display of a circular intersection such as a
rotary.
[0032] Alternatively, the technique may include: determining cross
points each between inner side lines of every two adjacent
width-imparted intersection-connected links, and connecting the
cross points in the order of the sorted intersection-connected
links to form a polygon; and
[0033] generating a predetermined circle including the polygon with
the intersection node as a center, determining cross points between
the circle and the side lines, and connecting the cross points in
the order of the sorted intersection-connected links to form a new
polygon as the intersection shape.
[0034] A polygon inscribed in a circle is a convex polygon without
fail. Therefore, this technique is useful in the case where display
of a concave polygon is difficult.
[0035] Preferably, after the step of generating an intersection
shape, the method further includes the steps of:
[0036] processing the intersection-connected links, including
reading information on accessories of the intersection-connected
links from the map data, and generating shapes of the accessories
and determining the positions of the accessories in the
intersection-connected links with reference to the intersection
shape; and
[0037] processing the intersection, including reading information
on accessories of the intersection node from the map data, and
generating shapes of the accessories and determining the positions
of the accessories in the intersection shape with reference to the
intersection shape,
[0038] wherein the step of processing the intersection-connected
links includes deleting portions of the accessories extending along
roads (such as center lines, lanes, side strips, and sidewalls)
that overlap the intersection shape.
[0039] Thus, as for accessories among those belonging to the
intersection-connected links that extend along the links, such as
center lines, lanes, side strips, and sidewalls, portions of these
accessories that overlap the generated intersection shape are
deleted. This prevents these accessories from protruding into the
area of the intersection, and thus the resultant intersection shape
is closer to the actual shape.
[0040] When the map data includes information that two of the
intersection-connected links connected to the intersection are
major roads, the step of processing the intersection preferably
includes connecting center lines and lanes belonging to the two
major roads among the deleted center lines and lanes belonging to
the intersection-connected links smoothly, to generate a center
line and lanes in the intersection shape.
[0041] By the above processing, if there is information that two of
the intersection-connected links are major roads, lanes and center
lines belonging to the two major roads are connected smoothly even
when lanes and center lines are deleted in the intersection as
described above. The resultant intersection shape has a marking
close to the actual marking for a major road.
[0042] Preferably, the step of generating an intersection shape
relates to generation of an intersection shape on a route from a
departure point to a destination or a stopover searched based on
the map data, and the step includes:
[0043] generating a vehicle path along a predetermined position on
the width-imparted intersection-connected links through which the
route runs; and
[0044] deleting a portion of the vehicle path that overlaps the
intersection shape and then connecting remainders of the vehicle
path in the areas other than the intersection shape separated by
the deletion smoothly, to generate a vehicle path in the
intersection shape.
[0045] Thus, when a route searched based on a road network and
information on the departure point and the destination is to be
displayed on the generated intersection shape, the following
processing is performed. That is, as for a vehicle path extending
along intersection-connected links through which the route runs, a
portion of the vehicle path that overlaps the intersection shape is
deleted, and then remainders of the vehicle path separated by the
deletion is connected smoothly in the intersection. In this way,
the vehicle path can be displayed in a form closer to the actual
path.
[0046] Further, preferably, when the map data includes information
on a stop line of the intersection-connected link, the step of
displaying the generated intersection shape includes generating the
distance from the position of a vehicle to the stop line as the
distance from the position of the vehicle to a coming intersection,
in the generation of notification information for guidance of the
vehicle based on the map data, the intersection shape, and the
route from a departure point to a destination or a stopover
searched based on the map data.
[0047] By adopting the above processing, the distance from the
position of the vehicle to the stop line, not to the intersection
node as the center of the intersection, is used for notification of
the distance between the vehicle and the coming intersection, such
as "300 m to next intersection", for example. This makes it
possible to provide guidance in a manner more agreeable to the
driver.
[0048] A second aspect is directed to a map display unit for
displaying a map for guidance. The unit includes:
[0049] a map data storage part for storing map data including a
road network;
[0050] a route search part for searching a route from a departure
point to a destination or a stopover based on the map data;
[0051] a vehicle position detection part for detecting the position
of a vehicle mounting the unit on the map data;
[0052] an intersection shape generation part for reading an
intersection node representing an intersection and
intersection-connected links representing roads connected to the
intersection node constituting the road network, and generating
width-imparted intersection-connected links and an intersection
shape at the intersection node based on the intersection node and
the intersection-connected links;
[0053] a guidance part for generating notification information for
guidance of the vehicle based on the map data, the intersection
shape, and the route searched; and
[0054] an output part for outputting the notification information
via map display or any other medium.
[0055] Preferably, the intersection shape generation part performs
the operation of:
[0056] generating a width-imparted intersection-connected link by
specifying a road width of each of the intersection-connected links
based on information associated with the intersection-connected
link, and drawing side lines representing edges of a road on the
right and left sides of the intersection-connected link based on
the specified road width; and
[0057] sorting the positions of the intersection-connected links
based on the bearings at which the intersection-connected links are
connected to the intersection node,
[0058] Thereafter, the following technique may be adopted.
[0059] The technique includes: determining cross points each
between inner side lines of every two adjacent width-imparted
intersection-connected links, and determining lines extending
orthogonal to the intersection-connected links at positions outside
the cross points with respect to the intersection node; and
[0060] determining cross points between the lines and the side
lines, and connecting the cross points in the order of the sorted
intersection-connected links to form a polygon as the intersection
shape.
[0061] Alternatively, the technique may include: determining cross
points each between inner side lines of every two adjacent
width-imparted intersection-connected links, and connecting the
cross points in the order of the sorted intersection-connected
links to form a polygon; and
[0062] determining new points by shifting the cross points as the
vertexes of the polygon by a predetermined distance along the side
lines crossing at the respective vertexes outward with respect to
the intersection node, and connecting the new points in the order
of the sorted intersection-connected links to form a new polygon as
the intersection shape.
[0063] Alternatively, the technique may include: determining cross
points each between inner side lines of every two adjacent
width-imparted intersection-connected links, and connecting the
cross points in the order of the sorted intersection-connected
links to form a polygon; and
[0064] generating a predetermined circle including the polygon with
the intersection node as a center, as the intersection shape.
[0065] Alternatively, the technique may include: determining cross
points each between inner side lines of every two adjacent
width-imparted intersection-connected links, and connecting the
cross points in the order of the sorted intersection-connected
links to form a polygon; and
[0066] generating a predetermined circle including the polygon with
the intersection node as a center, determining cross points between
the circle and the side lines, and connecting the cross points in
the order of the sorted intersection-connected links to form a new
polygon as the intersection shape.
[0067] Also, preferably, the intersection shape generation part
further performs the operation of:
[0068] reading information on accessories of the
intersection-connected links from the map data, and generating
shapes of the accessories and determining the positions of the
accessories in the intersection-connected links with reference to
the intersection shape, after the generation of the intersection
shape;
[0069] reading information on accessories of the intersection node
from the map data, and generating shapes of the accessories and
determining the positions of the accessories in the intersection
shape with reference to the intersection shape, after the
generation of the intersection shape; and
[0070] deleting portions of the accessories extending along roads
(such as center lines, lanes, side strips, and sidewalls) that
overlap the intersection shape.
[0071] When the map data includes information that two of the
intersection-connected links connected to the intersection are
major roads, the intersection shape generation part preferably
connects center lines and lanes belonging to the two major roads
among the deleted center lines and lanes belonging to the
intersection-connected links smoothly, to generate a center line
and lanes in the intersection shape.
[0072] Preferably, the intersection shape generation part generates
an intersection shape on a route from a departure point to a
destination or a stopover searched based on the map data, and
further performs the operation of:
[0073] generating a vehicle path along a predetermined position on
the width-imparted intersection-connected links through which the
route runs; and
[0074] deleting a portion of the vehicle path that overlaps the
intersection shape and then connecting remainders of the vehicle
path in the areas other than the intersection shape separated by
the deletion smoothly, to generate a vehicle path in the
intersection shape.
[0075] Further, preferably, when the map data includes information
on a stop line of the intersection-connected link, the guidance
part generates the distance from the position of the vehicle to the
stop line as the distance from the position of the vehicle to a
coming intersection.
[0076] As described above, the second aspect is directed to a map
display unit employing the intersection display method in the first
aspect. With the above construction, even a map display unit (such
as a navigation system) having a small memory capacity can display
an intersection shape.
[0077] A third aspect is directed to a recording medium containing
an intersection display method for generating and displaying an
intersection shape by use of map data including a road network
recorded as a computer-executable program. The program at least
executes the steps of:
[0078] reading from the map data an intersection node representing
an intersection and intersection-connected links representing roads
connected to the intersection node, constituting the road
network;
[0079] generating an intersection shape at the intersection node
and width-imparted intersection-connected links, based on the
intersection node and the intersection-connected links; and
[0080] displaying the intersection shape together with other
information for guidance notification.
[0081] Preferably, the step of generating an intersection shape
includes the steps of:
[0082] generating a width-imparted intersection-connected link by
specifying a road width of each of the intersection-connected links
based on information associated with the intersection-connected
link, and drawing side lines representing edges of the road on the
right and left sides of the intersection-connected link based on
the specified road width; and
[0083] sorting the positions of the intersection-connected links
based on the bearings at which the intersection-connected links are
connected to the intersection node.
[0084] Thereafter, the following technique may be adopted.
[0085] The technique includes: determining cross points each
between inner side lines of every two adjacent width-imparted
intersection-connected links, and determining lines extending
orthogonal to the intersection-connected links at positions outside
the cross points with respect to the intersection node; and
[0086] determining cross points between the lines and the side
lines, and connecting the cross points in the order of the sorted
intersection-connected links to form a polygon as the intersection
shape.
[0087] Alternatively, the technique may include: determining cross
points each between inner side lines of every two adjacent
width-imparted intersection-connected links, and connecting the
cross points in the order of the sorted intersection-connected
links to form a polygon; and
[0088] determining new points by shifting the cross points as the
vertexes of the polygon by a predetermined distance along the side
lines crossing at the respective vertexes outward with respect to
the intersection node, and connecting the new points in the order
of the sorted intersection-connected links to form a new polygon as
the intersection shape.
[0089] Alternatively, the technique may include: determining cross
points each between inner side lines of every two adjacent
width-imparted intersection-connected links, and connecting the
cross points in the order of the sorted intersection-connected
links to form a polygon; and
[0090] generating a predetermined circle including the polygon with
the intersection node as a center, as the intersection shape.
[0091] Alternatively, the technique may include: determining cross
points each between inner side lines of every two adjacent
width-imparted intersection-connected links, and connecting the
cross points in the order of the sorted intersection-connected
links to form a polygon; and
[0092] generating a predetermined circle including the polygon with
the intersection node as a center, determining cross points between
the circle and the side lines, and connecting the cross points in
the order of the sorted intersection-connected links to form a new
polygon as the intersection shape.
[0093] Also, preferably, after the step of generating an
intersection shape, the program further executes the steps of:
[0094] processing the intersection-connected links, including
reading information on accessories of the intersection-connected
links from the map data, and generating shapes of the accessories
and determining the positions of the accessories in the
intersection-connected links with reference to the intersection
shape; and
[0095] processing the intersection, including reading information
on accessories of the intersection node from the map data, and
generating shapes of the accessories and determining the positions
of the accessories in the intersection shape with reference to the
intersection shape,
[0096] wherein the step of processing the intersection-connected
links includes deleting portions of the accessories extending along
roads (such as center lines, lanes, side strips, and sidewalls)
that overlap the intersection shape.
[0097] When the map data includes information that two of the
intersection-connected links connected to the intersection are
major roads, the step of processing the intersection preferably
includes connecting center lines and lanes belonging to the two
major roads among the deleted center lines and lanes belonging to
the intersection-connected links smoothly, to generate a center
line and lanes in the intersection shape.
[0098] Preferably, the step of generating an intersection shape
relates to generation of an intersection shape on a route from a
departure point to a destination or a stopover searched based on
the map data, and the step further includes the steps of:
[0099] generating a vehicle path along a predetermined position on
the width-imparted intersection-connected links through which the
route runs; and
[0100] deleting a portion of the vehicle path that overlaps the
intersection shape and then connecting remainders of the vehicle
path in the areas other than the intersection shape separated by
the deletion smoothly, to generate a vehicle path in the
intersection shape.
[0101] Further, preferably, when the map data includes information
on a stop line of the intersection-connected link, the step of
displaying the generated intersection shape includes generating the
distance from the position of a vehicle to the stop line as the
distance from the position of the vehicle to a coming intersection,
in the generation of notification information for guidance of the
vehicle based on the map data, the intersection shape, and the
route from a departure point to a destination or a stopover
searched based on the map data.
[0102] As described above, the third aspect is directed to a
recording medium containing a program for executing the
intersection display method of the first aspect. This aims to
provide the intersection display method of the first aspect to
existing display units in the form of software.
[0103] A fourth aspect of the present invention is directed to a
data recording medium containing recorded computer-readable data.
The data includes:
[0104] data on an intersection node representing an intersection
constituting a road network;
[0105] data on intersection-connected links representing roads
connected to the intersection node constituting the road network;
and
[0106] data on an intersection shape corresponding to the
intersection node, generated based on the intersection node and the
intersection-connected links.
[0107] Preferably, the intersection shape is a polygon formed
by:
[0108] generating a width-imparted intersection-connected link by
specifying a road width of each of the intersection-connected links
based on information associated with the intersection-connected
link, and drawing side lines representing edges of the road on the
right and left sides of the intersection-connected link based on
the specified road width;
[0109] sorting the positions of the intersection-connected links
based on the bearings at which the intersection-connected links are
connected to the intersection node;
[0110] determining a cross point between inner side lines for every
two adjacent width-imparted intersection-connected links, and
determining lines extending orthogonal to the
intersection-connected links at positions outside the cross points
with respect to the intersection node; and
[0111] determining cross points between the lines and the side
lines, and connecting the cross points in the order of the sorted
intersection-connected links.
[0112] Alternatively, preferably, the intersection shape is a
polygon formed by:
[0113] generating a width-imparted intersection-connected link by
specifying a road width of each of the intersection-connected links
based on information associated with the intersection-connected
link, and drawing side lines representing edges of the road on the
right and left sides of the intersection-connected link based on
the specified road width;
[0114] sorting the positions of the intersection-connected links
based on the bearings at which the intersection-connected links are
connected to the intersection node;
[0115] determining cross points each between inner side lines of
every two adjacent width-imparted intersection-connected links, and
connecting the cross points in the order of the sorted
intersection-connected links to form a provisional polygon; and
[0116] determining new points by shifting the cross points as the
vertexes of the provisional polygon by a predetermined distance
along the side lines crossing at the respective vertexes outward
with respect to the intersection node, and connecting the new
points in the order of the sorted intersection-connected links.
[0117] Alternatively, preferably, the intersection shape is a
predetermined circle formed by:
[0118] generating a width-imparted intersection-connected link by
specifying a road width of each of the intersection-connected links
based on information associated with the intersection-connected
link, and drawing side lines representing edges of the road on the
right and left sides of the intersection-connected link based on
the specified road width;
[0119] sorting the positions of the intersection-connected links
based on the bearings at which the intersection-connected links are
connected to the intersection node;
[0120] determining cross points each between inner side lines of
every two adjacent width-imparted intersection-connected links, and
connecting the cross points in the order of the sorted
intersection-connected links to form a polygon; and
[0121] generating the predetermined circle including the polygon
with the intersection node as a center.
[0122] Alternatively, preferably, the intersection shape is a
polygon formed by:
[0123] generating a width-imparted intersection-connected link by
specifying a road width of each of the intersection-connected links
based on information associated with the intersection-connected
link, and drawing side lines representing edges of the road on the
right and left sides of the intersection-connected link based on
the specified road width;
[0124] sorting the positions of the intersection-connected links
based on the bearings at which the intersection-connected links are
connected to the intersection node;
[0125] determining cross points each between inner side lines of
every two adjacent width-imparted intersection-connected links, and
connecting the cross points in the order of the sorted
intersection-connected links to form a provisional polygon; and
[0126] generating a predetermined circle including the provisional
polygon with the intersection node as a center, determining cross
points between the circle and the side lines, and connecting the
cross points in the order of the sorted intersection-connected
links.
[0127] As described above, in the fourth aspect, intersection
shapes are prepared in advance using a high-throughput apparatus
such as a workstation and a computer. The prepared intersection
shapes are recorded on a recording medium so as to be associated
with respective inspection nodes in a small-capacity road network.
Thus, using such a recording medium, display of intersection shapes
can be realized even by a map display unit that is poor in
operation throughput and finds difficulty in directly calculating
intersection shapes from a road network map on a display, without
heavily burdening an arithmetic part and a memory of the unit.
[0128] These and other objects, features, aspects and advantages of
the present invention will become more apparent from the following
detailed description of the present invention when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0129] FIGS. 1a and 1b are illustrations that demonstrate the
concept of the intersection display method to be realized by the
invention;
[0130] FIG. 2 is a block diagram of the construction of a map
display unit employing an intersection display method of a first
embodiment of the invention;
[0131] FIG. 3 is a flowchart showing an example of the operation of
an intersection shape generation part 5 in FIG. 2;
[0132] FIG. 4 is an illustration demonstrating an example of
generation of width-imparted intersection-connected links at an
intersection according to steps S11 to S14 in FIG. 3;
[0133] FIG. 5 is a flowchart showing in more detail an example of
the operation in sub-routine step S15 (generation of intersection
shape) in FIG. 3;
[0134] FIG. 6 is an illustration demonstrating an example of
generation of an intersection shape according to the steps in FIG.
5;
[0135] FIG. 7 is a flowchart showing in more detail another example
of the operation in sub-routine step S15 (generation of
intersection shape) in FIG. 3;
[0136] FIG. 8 is an illustration demonstrating an example of
generation of an intersection shape according to the steps in FIG.
7;
[0137] FIG. 9 is a flowchart showing in more detail yet another
example of the operation in sub-routine step S15 (generation of
intersection shape) in FIG. 3;
[0138] FIG. 10 is an illustration demonstrating an example of
generation of an intersection shape according to the steps in FIG.
9;
[0139] FIG. 11 is a flowchart showing in more detail yet another
example of the operation in sub-routine step S15 (generation of
intersection shape) in FIG. 3;
[0140] FIG. 12 is an illustration demonstrating an example of
generation of an intersection shape according to the steps in FIG.
11;
[0141] FIG. 13 is a block diagram of the construction of a map
display unit employing an intersection display method of a second
embodiment of the invention;
[0142] FIG. 14 is a flowchart showing an example of the operation
of an intersection shape generation part 15 in FIG. 13 performed in
addition to the operation of the intersection shape generation part
5 in FIG. 2;
[0143] FIG. 15 is an illustration demonstrating an example of
generation of an intersection shape provided with
intersection-connected link accessories according to steps S21 to
S24 in FIG. 14;
[0144] FIG. 16 is an illustration demonstrating an example of
generation of an intersection shape provided with intersection
accessories according to steps S25 to S28 in FIG. 14;
[0145] FIG. 17 is an illustration demonstrating a concept in
notification of the distance from the current position to a coming
intersection; and
[0146] FIG. 18 is a flowchart showing the operation of calculating
the distance from the current position to a coming intersection
executed by a guidance part 6 in FIG. 13.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0147] (Basic concept of the invention)
[0148] Before describing embodiments of the invention in detail,
the basic concept of the invention will be described for easy
understanding of the invention.
[0149] The intersection display method of the invention aims to
generate and display an intersection shape closer to the actual
shape. To attain this aim, the intersection display method of the
invention uses a road network included in map data as a basis, and
automatically generates and displays the shape of an intersection
existing in the road network.
[0150] As described above, in order to display roads in shapes
closer to the actual shapes, some conventional technique generates
and displays width-imparted roads by providing road links with
widths corresponding to the actual road widths. In such a
conventional technique, width-imparted roads corresponding to links
connected to a node are placed to overlap each other at the node
(intersection), and the overlap portion is simply considered as the
intersection (FIG. 1a). In this case, therefore, the shape of the
intersection is not always determined.
[0151] In the above conventional technique, therefore, it is
difficult to perform processing that can only be performed on the
premise that the intersection shape has been determined, such as
correcting the intersection shape into a natural shape, placing
intersection accessories in consideration of the intersection
shape, and drawing a smooth driving path in the intersection.
[0152] In view of the above, the intersection display method of the
invention first determines width-imparted roads for respective
links connected to an intersection, and then determines the
intersection shape based on the shapes of the width-imparted roads
(FIG. 1b).
[0153] In addition, the intersection display method of the
invention determines the shapes and positions of intersection
accessories such as an island in a rotary, a marking for right-turn
vehicle guidance, crosswalks, stop lines, lanes, center lines, side
strips, and sidewalls based on the determined intersection shape,
so as to display the intersection in a more natural shape.
[0154] Moreover, according to the invention, the thus-generated
intersection shapes are stored in a storage part in association
with respective intersections in a road network. Thus, a road
network map provided with intersection shapes is prepared as a new
map form. By storing this road network map provided with
intersection shapes, the above technique of the invention can also
be employed by map display units having a throughput too small to
directly generate intersection shapes by themselves. In addition,
being smaller in capacity than a town map, the road network map
provided with intersection shapes is advantageous in the case of
being stored in map display units having a small memory capacity
and in the case of map distribution via communications.
[0155] It should be noted that the above description of the basic
concept of the invention is intended only for easy understanding of
the invention and by no means allowed to be used to unduly narrow
the scope of the invention.
[0156] Hereinafter, embodiments of the present invention will be
described with reference to the relevant drawings.
[0157] (First Embodiment)
[0158] FIG. 2 is a block diagram of the construction of a map
display unit employing an intersection display method of the first
embodiment of the invention. Referring to FIG. 2, the map display
unit of the first embodiment includes an input part 1, a map data
storage part 2, a route search part 3, a position detection part 4,
an intersection shape generation part 5, a guidance part 6, and an
output part 7.
[0159] The intersection display method of the first embodiment is
basically realized by the intersection shape generation part 5. For
easy understanding, however, the entire map display unit employing
the intersection display method will be first outlined. Note that
the constructions of the input part 1, the map data storage part 2,
the route search part 3, the position detection part 4, the
guidance part 6, and the output part 7 are not restricted to those
exemplified in the following description, but any of constructions
used in known map display units may be adopted.
[0160] The input part 1 includes a remote controller, a touch
sensor, a keyboard, a mouse, and the like operated by the user, for
example, and is used to input instructions such as selection of
functions of the map display unit (change of the item to be
processed, switch of the map, change of the hierarchical level, and
the like), setting of a departure point and a destination
(including a stopover), and selection of a route search mode.
Instruction information output from the input part 1 is supplied to
the route search part 3 and the guidance part 6.
[0161] The map data storage part 2 includes an optical disk (CD,
DVD, and the like), a hard disk, a large-capacity memory, and the
like, for example, for storing information relating to a road
network (map data) such as the connection status, coordinates,
shapes, attributes, and regulations for respective intersections
and roads. The map data stored in the map data storage part 2 is
read and used as appropriate by the route research part 3, the
intersection shape generation part 5, and the guidance part 6. The
map data stored in the map data storage part 2 may be
two-dimensional map data or three-dimensional map data.
[0162] The position detection part 4 includes a GPS, a radio beacon
receiver, a vehicle speed sensor, various speed sensors, an
absolute bearing sensor, and the like, for detecting the current
position of a vehicle. Vehicle current position information
outputted from the position detection part 4 is supplied to the
route search part 3 and the guidance part 6.
[0163] The route search part 3 reads map data in a necessary range
from the map data storage part 2 according to the instruction
information received from the input part 1. The route search part 3
then determines the departure point and the destination based on
the received instruction information such as location information,
and searches for a minimum-cost route from the departure point to
the destination in consideration of intersection traffic regulation
and one-way traffic regulation if any.
[0164] To state a specific example, upon receipt of an instruction
of executing the route search mode from the input part 1, the route
search part 3 sets, as the departure point of the search, either
the departure point inputted into the input part 1 or the vehicle
current position detected by the position detection part 4, and
sets as the destination of the search the destination inputted into
the input part 1. The route search part 3 also reads map data in a
range covering the area from the departure point to the destination
from the map data storage part 2. Then, the route search part 3
searches for a guidance route (for example, a shortest-time route
or a shortest-distance route) from the departure point to the
destination on the read map data. As an algorithm for the route
search executed by the route search part 3, known Dijkstra
algorithm, for example, is used.
[0165] Upon completion of the route search, the route search part 3
outputs the resultant route information to the intersection shape
generation part 5 and the guidance part 6.
[0166] The intersection shape generation part 5 executes a
predetermined operation to be described later, based on the route
information received from the route search part 3 and the map data
(the same map data as that read by the route search part 3)
received from the map data storage part 2, to generate information
on the shape of an intersection existing on the route searched by
the route search part 3.
[0167] The generated intersection shape information is held in the
intersection shape generation part 5, which is used by being read
the guidance part 6 as appropriate.
[0168] The guidance part 6 generates guidance information including
the intersection shape based on the route information received from
the route search part 3, the vehicle current position information
received from the position detection part 4, the map data received
from the map data storage part 2, and the intersection shape
information received from the intersection shape generation part
5.
[0169] To state a specific example, upon receipt of an instruction
of executing a guidance notification mode from the input part 1,
the guidance part 6 first generates guidance information for
notifying the route to be driven by the user on the map based on
the route information, the vehicle current position information,
and the map data. As the vehicle current position approaches an
intersection on the route, the guidance part 6 reads intersection
shape information on the intersection in question among all the
intersection shape information held in the intersection shape
generation part 5, and generates guidance information for
displaying the intersection shape. The generated guidance
information is outputted to the output part 7.
[0170] The output part 7 includes a display device (a liquid
crystal display, a CRT display, and the like) and displays an image
for guidance notification on a screen, or outputs sound via a
speaker or the like, based on the guidance information received
from the guidance part 6.
[0171] Hereinafter, the intersection display method (intersection
shape generation method) of the first embodiment of the invention
will be described in a concrete manner with reference to FIGS. 3 to
12.
[0172] FIG. 3 is a flowchart showing an example of the operation
executed by the intersection shape generation part 5 of FIG. 2.
FIG. 4 is an illustration that demonstrates an example of
generation of width-imparted intersection-connected links at an
intersection according to steps S11 to S14 in FIG. 3. FIGS. 5, 7,
9, and 11 are flowcharts showing in more detail examples of the
operation of sub-routine step S15 (intersection shape generation)
in FIG. 3. FIGS. 6, 8, 10, and 12 are illustrations that
demonstrate examples of generation of intersection shapes according
to the steps in FIGS. 5, 7, 9, and 11, respectively.
[0173] First, referring to FIGS. 3 and 4, the intersection shape
generation part 5 receives the route information from the route
search part 3 and reads map data in the area near the route from
the map data storage part 2 (step S11). The intersection shape
generation part 5 extracts one intersection (intersection node)
existing on the route from the read map data, and further extracts
road links connected to the extracted intersection (hereinafter,
these road links are referred to as intersection-connected links)
(step S12). Next, the intersection shape generation part 5 reads
attribute data of the extracted intersection-connected links, such
as the actual road width, the numbers of up lanes and down lanes,
and the road type, from the map data storage part 2, to specify the
road widths from the center line to the left side and the right
side of each intersection-connected link (step S13). In the case
where no attribute data such as the actual road width of an
intersection-connected link is stored in the map data storage part
2, the road width may be determined using a predetermined default
value. The intersection shape generation part 5 then draws new
lines with respect to every intersection-connected links to be
connected to the intersection by translating the line representing
each intersection-connected link as a center line rightward and
leftward by the specified road widths, to determines right and left
side lines of the intersection-connected link (step S14).
[0174] By the above processing, width-imparted
intersection-connected links provided with road widths
corresponding to the actual road widths are generated for the
respective intersection-connected links (FIG. 4).
[0175] Next, the intersection shape generation part 5 generates an
intersection shape based on the generated width-imparted
intersection-connected links (step S15).
[0176] Various techniques may be employed to generate an
intersection shape. Hereinafter, four exemplary techniques among
those will be described.
[0177] The first technique will be described with reference to
FIGS. 5 and 6.
[0178] The intersection shape generation part 5 sorts a group of
intersection-connected links connected to an intersection according
to the bearings at which the links are connected to the
intersection (for example, so that the links are arranged clockwise
starting from the true north) (step S101). Thereafter, the
intersection shape generation part 5 determines a cross point E
between the inner side lines of every two adjacent
intersection-connected links (step S102). The cross point of the
inner side lines refers to a point of intersection between the
right side line of the left-hand intersection-connected link and
the left side line of the right-hand intersection-connected link.
The intersection shape generation part 5 then determines lines B
extending orthogonal to the intersection-connected links at
positions outside the cross points E with respect to the
intersection node (step S103). The positions may be determined
arbitrarily in consideration of the display size of the
intersection and the like. Thereafter, the intersection shape
generation part 5 determines points C at which the lines B cross
the right and left side lines, and connects the points C in the
order of the sorted intersection-connected links, to form a polygon
as an intersection shape D (step S104).
[0179] The second technique will be described with reference to
FIGS. 7 and 8.
[0180] As in step S101 described above, the intersection shape
generation part 5 sorts a group of intersection-connected links
connected to an intersection according to the bearings at which the
links are connected to the intersection (step S201). The
intersection shape generation part 5 then determines a cross point
E between the inner side lines of every two adjacent
intersection-connected links, and connects the cross points E in
the order of the sorted intersection-connected links, to form a
polygon as a provisional intersection shape F (step S202). The
cross point between the inner side lines is defined as described
above. Thereafter, the intersection shape generation part 5
determines a distance G by which the vertexes of the provisional
intersection shape F (that is, the cross points E between the inner
side lines) are shifted (step S203). The distance G may be
determined arbitrarily in consideration of the display size of the
intersection and the like. The intersection shape generation part 5
then determines points H by shifting, outward with respect to the
intersection node, each vertex of the provisional intersection
shape F by the distance G along the two side lines crossing at the
vertex (step S204). Subsequently, the intersection shape generation
part 5 connects the resultant points H in the order of the sorted
intersection-connected links, to form a polygon as a final
intersection shape I (step S205).
[0181] The third technique will be described with reference to
FIGS. 9 and 10.
[0182] As in step S101 described above, the intersection shape
generation part 5 sorts a group of intersection-connected links
connected to an intersection according to the bearings at which the
links are connected to the intersection (step S301). Thereafter, as
in step S202 described above, the intersection shape generation
part 5 determines a cross point E between the inner side lines of
every two adjacent intersection-connected links, and connects the
cross points E in the order of the sorted intersection-connected
links, to form a polygon as a provisional intersection shape F
(step S302). The cross point between the inner side lines is
defined as described above. The intersection shape generation part
5 then forms a circle J that includes the provisional intersection
shape F, as a final intersection shape K (step S303). The center of
the circle J may be determined arbitrarily as long as the circle
includes the provisional intersection shape F. For example, when
the center of the circle J is equal to the intersection node, the
radius of the circle J is equal to or more than the maximum of the
distances between the intersection node and the vertexes of the
provisional intersection shape F.
[0183] The third technique is useful when the intersection is a
rotary or when the intersection shape is displayed in an abstract
form.
[0184] The fourth technique will be described with reference to
FIGS. 11 and 12.
[0185] As in step S101 described above, the intersection shape
generation part 5 sorts a group of intersection-connected links
connected to an intersection according to the bearings at which the
links are connected to the intersection (step S401). Thereafter, as
in step S202 described above, the intersection shape generation
part 5 determines a cross point E between the inner side lines of
every two adjacent intersection-connected links, and connects the
cross points E in the order of the sorted intersection-connected
links, to form a polygon as a provisional intersection shape F
(step S402). The cross point of the inner side lines is defined as
described above. The intersection shape generation part 5 then
forms a circle J that includes the provisional intersection shape F
(step S403). The center of the circle J may be determined
arbitrarily as long as the circle includes the provisional
intersection shape F, as described above. Thereafter, the
intersection shape generation part 5 determines points L at which
the circle J crosses with the right and left side lines of the
respective intersection-connected links. The points L are connected
in the order of the sorted intersection-connected links, to form a
polygon as an intersection shape M (step S404).
[0186] A polygon inscribed in the circle J is a convex polygon
without fail. Therefore, the fourth technique is useful in the case
where the output part 7 finds difficulty in displaying a concave
polygon.
[0187] Referring back to FIG. 3, once generation of the shape of
one intersection is completed in step S15, the intersection shape
generation part 5 examines whether or not there remains an
intersection on the route that has not been subjected to the
intersection shape generation processing (step S16). If it is
determined in step S16 that there remains an intersection that has
not been subjected to the process, the operation returns to step
S12 to repeat the process described above for this intersection. If
it is determined that there remains no intersection, the
intersection shape generation process is terminated.
[0188] Thus, according to the intersection display method of the
first embodiment of the invention, the shape of an intersection is
generated based on road network information included in existing
map data.
[0189] Thus, in road map display, an intersection shape closer to
the actual shape can be displayed. In addition, the capacity
required for map data can be smaller compared with the case of
generating an intersection shape using a town map.
[0190] (Second Embodiment)
[0191] In the first embodiment above, described was a basic method
for generating an intersection shape based on road network
information included in existing map data and displaying the
resultant intersection.
[0192] In a second embodiment, an intersection display method with
improved user convenience is provided by storing specific
information in advance in the map data storage part and utilizing
the specific information as well as the intersection shape
generated by any of the above techniques.
[0193] FIG. 13 is a block diagram of the construction of a map
display unit employing an intersection display method of the second
embodiment of the invention. Referring to FIG. 13, the map display
unit of the second embodiment includes the input part 1, a map data
storage part 12, the route search part 3, the position detection
part 4, an intersection shape generation part 15, the guidance part
6, and the output part 7.
[0194] As is apparent from FIG. 13, the map display unit of the
second embodiment includes the map data storage part 12 and the
intersection shape generation part 15 in place of the map data
storage part 2 and the intersection shape generation part 5 in the
first embodiment, respectively. The other components of the map
display unit of the second embodiment are the same as those of the
map display unit of the first embodiment. The same components are
denoted by the same reference numerals, and the description thereof
is omitted here.
[0195] Basically, the intersection display method of the second
embodiment of the invention is realized by the map data storage
part 12 and the intersection shape generation part 15.
[0196] In the map data storage part 12, stored in advance is
specific information such as whether or not a center line, a
sidewall/shoulder, and a crosswalk respectively exist, and the
number of lanes for each road link, and whether or not a rotary, a
marking for right-turn vehicle guidance, and a major road
respectively exist for each intersection node, in addition to the
map data described above.
[0197] The intersection shape generation part 15 first executes the
predetermined operations described in the first embodiment based on
the route information received from the route search part 3 and the
map data (the same map data as that read by the route search part
3) received from the map data storage part 12, to generate
information on the shape of an intersection existing on the route
searched by the route search part 3. The intersection shape
generation part 15 then reads the specific information on the
intersection in question from the map data storage part 12, to
determine the positions and shapes of intersection-connected link
accessories and the positions and shapes of intersection
accessories, and add the results to the intersection shape
information.
[0198] The thus-generated intersection shape information is held in
the intersection shape generation part 15, which is used by being
read by the guidance part 6 as appropriate.
[0199] Hereinafter, the intersection display method (intersection
shape generation method) of the second embodiment of the invention
will be described in a concrete manner with reference to FIGS. 14
to 16.
[0200] FIG. 14 is a flowchart showing an example of the operation
additionally executed by the intersection shape generation part 15
shown in FIG. 13, which also executes the operation described above
as being executed by the intersection shape generation part 5 shown
in FIG. 2. The steps in FIG. 14 are preferably executed between
steps S15 and S16 in FIG. 3. FIG. 15 is an illustration that
demonstrates an example of generation of an intersection shape
provided with intersection-connected link accessories according to
steps S21 to S24 in FIG. 14. FIG. 16 is an illustration that
demonstrates an example of generation of an intersection shape
provided with intersection accessories according to steps S25 to
S28 in FIG. 14.
[0201] First, referring to FIGS. 14 and 15, the intersection shape
generation part 15 reads information such as whether or not a
center line, a sidewall/shoulder, and a crosswalk respectively
exist and the number of lanes for each intersection-connected link
from the map data storage part 12 (step S21). The intersection
shape generation part 15 then places a center line when it exists,
a sidewall or a shoulder when it exists, and lanes corresponding to
the number of lanes, so that these extend in parallel with the
intersection-connected link (step S22). The intersection shape
generation part 15 also places a vehicle path so as to run along
the center of the lane when the route supplied from the route
search part 3 passes through the intersection-connection link in
question (step S22). By this placement, the accessories and the
vehicle path are also formed in the area of the intersection shape.
Therefore, the intersection shape generation part 15 cuts off
portions of the accessories and vehicle path overlapping the
intersection shape to remove unnecessary portions (step S23). Thus,
centerlines, sidewalls/shoulders, lanes, and vehicle paths are
generated in the areas outside the intersection shape. The
intersection shape generation part 15 further generates crosswalks
and stop lines as required at locations on the width-imparted
intersection-connected links to extend in parallel with the sides
of the intersection shape orthogonal to the intersection-connected
links (step S24).
[0202] Next, referring to FIGS. 14 and 16, the intersection shape
generation part 15 reads information such as whether or not a
rotary, a marking for right-turn vehicle guidance, and a major road
respectively exist in the intersection from the map data storage
part 12 (step S25). The intersection shape generation part 15 then
places a rotary when it exists and a marking for right-turn vehicle
guidance when it exists, at the position of the intersection node
(step S26). When a major road exists, the intersection shape
generation part 15 reads two intersection-connected links
designated as a major road from the map data storage part 12, and
connects the center lines and the lanes of the two
intersection-connected links smoothly to display a center line and
lanes of the major road in the intersection shape (step S27). For
connection of the separate two lines smoothly, a known method such
as spline interpolation and a method using Bezier curve may be
used. The intersection shape generation part 15 then selects two
intersection-connected links through which the route runs based on
the route information received from the route search part 3, and
connects the vehicle paths of the two intersection-connected links
smoothly, to display a vehicle path in the intersection shape (step
S28).
[0203] The guidance part 6 generates guidance information on the
intersection based on the thus-generated intersection shape
information, and presents the resultant information to the user via
the output part 7.
[0204] More specifically, once the vehicle current position enters
a range of a predetermined distance from a next intersection, the
guidance part 6 obtains the intersection shape information on the
next intersection from the intersection shape generation part 15.
The guidance part 6 then outputs the shape of the next intersection
that will be soon passed through by the vehicle, as well as the
vehicle path, to the output part 7.
[0205] It is probably more agreeable to the driver to be notified
of the distance from a coming intersection by the distance between
the vehicle current position and the stop line placed before the
intersection than by the distance between the vehicle current
position and the intersection node (center of the intersection)
(FIG. 17). Therefore, the guidance part 6 can determine the
distance from the intersection in the following manner.
[0206] Referring to FIG. 18, the guidance part 6 first determines a
coming intersection node (step S31). The guidance part 6 then
determines the distance between the vehicle current position and
the determined intersection node (step S32). Subsequently, the
guidance part 6 determines a correction distance between the
intersection node and a stop line position (see FIG. 17) (step
S33), and then determines the distance between the vehicle current
position and the stop line position considering the correction
distance (step S34).
[0207] As described above, in the intersection display method of
the second embodiment of the invention, in addition to generation
of the intersection shape based on the road network information in
the map data, shapes of accessories of the intersection-connected
links and the intersection are generated based on specific
information on the road links and the intersection node.
[0208] Thus, in road map display, an intersection shape closer to
the actual shape can be displayed. In addition, the capacity
required for map data can be smaller compared with the case of
generating an intersection shape using a town map. Moreover, it is
possible to place accessories of an intersection such as an island
of a rotary and a marking for right-turn vehicle guidance and
accessories of each intersection-connected link such as a crosswalk
and a stop line, in addition to the intersection shape. As a
result, an intersection can be displayed in a shape further closer
to the actual shape.
[0209] In the above embodiments, intersection shapes were generated
by the intersection shape generation part 5 or 15 as occasion
arose. However, for units poor in CPU performance or memory
capacity that requires considerably long time to generate an
intersection shape, it is possible to prepare in advance
intersection shapes for all intersections on the route using a
high-speed workstation, personal computer, or the like and then
store the prepared intersection shapes in association with the
respective intersections in the road network map. In this case, the
operation to be executed by the intersection shape generation part
5 or 15 shown in the flowchart of FIG. 3 will be executed by a
high-speed computer, and the generated intersection shapes are
stored in the map data storage part 2 or 12 together with the road
network. In the actual operation of the map display unit, the
stored intersection shape is read from the map data storage part 2
or 12, and, in the second embodiment, steps S21 to S28 in FIG. 14
are further executed. By this alternative method, also, the effect
described above can be obtained.
[0210] The thus-produced road network map with intersection shapes
is smaller in capacity than a town map with intersection shapes
mainly obtained by actual measurement. This makes it possible to
store a map covering an extensive area in a map display unit. Also,
this provides an advantage when a map is distributed via
communications or broadcasting.
[0211] In the above embodiments, the functions of the route search
part 3, the intersection shape generation part 5 or 15, and the
guidance part 6 may be realized by CPU software control. In this
case, a recording medium containing a program for the software
control must be mounted in the map display unit.
[0212] While the invention has been described in detail, the
foregoing description is in all aspects illustrative and not
restrictive. It is understood that numerous other modifications and
variations can be devised without departing from the scope of the
invention.
* * * * *