U.S. patent application number 09/781152 was filed with the patent office on 2001-08-23 for device and method for changing map information.
Invention is credited to Ata, Teruaki, Hamada, Hiroyuki, Sakamoto, Kiyomi, Yamashita, Atsushi.
Application Number | 20010016796 09/781152 |
Document ID | / |
Family ID | 18559929 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010016796 |
Kind Code |
A1 |
Ata, Teruaki ; et
al. |
August 23, 2001 |
Device and method for changing map information
Abstract
A map information storage 10 stores map information including
roads, landmarks, and areas. An overlap determination unit 11a
determines whether a landmark and an area overlap with a road in
consideration of a road and its width. A position changer 12 moves
the overlapping landmark and area to positions at which they do not
overlap with the road on width display. A changed map information
storage 13 stores map information including changed positional
information of the landmarks and the areas. If the changed map
information is displayed on a screen, the landmarks and the areas
are displayed so as not to overlap with roads on width display.
Inventors: |
Ata, Teruaki; (Osaka,
JP) ; Hamada, Hiroyuki; (Yawata, JP) ;
Yamashita, Atsushi; (Osaka, JP) ; Sakamoto,
Kiyomi; (Ikoma, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
18559929 |
Appl. No.: |
09/781152 |
Filed: |
February 13, 2001 |
Current U.S.
Class: |
701/438 ;
340/995.24 |
Current CPC
Class: |
G01C 21/3682
20130101 |
Class at
Publication: |
701/208 ;
340/995 |
International
Class: |
G01C 021/32 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 14, 2000 |
JP |
2000-35774 |
Claims
What is claimed is:
1. A map information changing device for changing positions of
landmarks and areas included in map information, said device
comprising: map information storage means for storing said map
information at least related to roads, the landmarks, and the
areas; overlap determination means for determining whether the
landmark and the area included in said map information overlap with
the road included in said map information and displayed with a road
width; position change means for changing positional information of
the landmark and the area determined by said overlap determination
means as overlapping with one or more roads by moving each of the
landmark and the area to a position at which each of the landmark
and the area does not overlap with said one or more roads displayed
with the road width, while keeping a location side of each of the
landmark and the area with respect to a center line of each road;
and changed map information storage means for storing said map
information and the positional information of the landmark and the
area changed by said position change means.
2. The map information changing device according to claim 1,
wherein said position change means moves the landmark away from the
center line of each of said one or more roads.
3. The map information changing device according to claim 1,
wherein said position change means moves each vertex of the area
away from the center line of each of said one or more roads.
4. The map information changing device according to claim 3,
wherein said position change means deforms the area in a direction
away from the center line of each of said one or more roads.
5. The map information changing device according to claim 3,
wherein said position change means translates the area away from
the center line of each of said one or more roads.
6. The map information changing device according to claim 1,
further comprising map information display means for displaying, on
a screen, the changed map information stored in said changed map
information storage means with the road width.
7. The map information changing device according to claim 6,
wherein said overlap determination means and said position change
means switch the road width to another road width based on an input
from a user.
8. A navigation device comprising the map information changing
device of claim 6.
9. A method for changing positions of landmarks and areas included
in map information, said method comprising the steps of: storing
said map information at least related to roads, the landmarks, and
the areas; determining whether the landmark and the area included
in said map information overlap with the road included in said map
information and displayed with a road width; changing positional
information of the landmark and the area determined in said overlap
determining step as overlapping with one or more roads by moving
each of the landmark and the area to a position at which each of
the landmark and the area does not overlap with said one or more
roads displayed with the road width, while keeping a location side
of each of the landmark and the area with respect to a center line
of each road; and storing said map information and the positional
information of the landmark and the area changed in said positional
information changing step.
10. The map information changing method according to claim 9,
wherein in said positional information changing step, the landmark
is moved away from the center line of each of said one or more
roads.
11. The map information changing method according to claim 9,
wherein in said positional information changing step, each vertex
of the area is moved away from the center line of each of said one
or more roads.
12. The map information changing method according to claim 12,
wherein in said positional information changing step, the area is
deformed in a direction away from the center line of each of said
one or more roads.
13. The map information changing method according to claim 11,
wherein in said positional information changing step, the area is
translated away from the center line of each of said one or more
roads.
14. A map information changing device for changing positions of
roads included in map information, said device comprising: map
information storage means for storing said map information at least
related to the roads, landmarks, and areas; overlap determination
means for determining whether the road included in said map
information and displayed with a road width overlaps with the
landmark and the area included in said map information; position
change means for changing positional information of the road
determined by said overlap determination means as overlapping with
one or more landmarks and areas by moving the road displayed with
the road width to a position at which the road does not overlap
with said one or more landmarks and areas, while keeping a location
side of each of the landmarks and the areas with respect to a
center line of the road; and changed map information storage means
for storing said map information and the positional information of
the road changed by said position change means.
15. The map information changing device according to claim 14,
wherein said position change means moves each endpoint of a segment
composing the road away from said one or more landmarks and
areas.
16. The map information changing device according to claim 15,
wherein said position change means translates the road away from
said one or more landmarks and areas.
17. The map information changing device according to claim 15,
wherein said position change means moves one endpoint of the
segment composing the road away from said one or more landmarks and
areas.
18. The map information changing device according to claim 14,
further comprising map information display means for displaying, on
a screen, the changed map information stored in said changed map
information storage means with the road width.
19. The map information changing device according to claim 18,
wherein said overlap determination means and said position change
means switch the road width to another road width based on an input
from a user.
20. A navigation device comprising the map information changing
device of claim 18.
21. A method for changing positions of roads included in map
information, said method comprising the steps of: storing said map
information at least related to the roads, landmarks, and areas;
determining whether the road included in said map information and
displayed with a road width overlaps with the landmark and the area
included in said map information; changing positional information
of the road determined in said overlap determining step as
overlapping with one or more landmarks and areas by moving the road
displayed with the road width to a position at which the road does
not overlap with said one or more landmarks and areas, while
keeping a location side of each of the landmarks and the areas with
respect to a center line of the road; and storing said map
information and the positional information of the road changed in
said positional information changing step.
22. The map information changing method according to claim 21,
wherein in said positional information changing step, each endpoint
of a segment composing the road is moved away from said one or more
landmarks and areas.
23. The map information changing method according to claim 22,
wherein in said positional information changing step, the road is
translated away from said one or more landmarks and areas.
24. The map information changing method according to claim 22,
wherein in said positional information changing step, one endpoint
of the segment composing the road is moved away from said one or
more landmarks and areas.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to devices and methods for
changing positions of landmarks, areas, or roads included in map
information and, more specifically, to a device and method for
automatically changing these positions so that the landmarks and
areas do not overlapwith each road displayed with a road width.
[0003] 2. Description of the Background Art
[0004] Navigation devices for vehicles provide users with guidance
to a destination by displaying map information stored in a storage
medium, such as CD-ROM, on a screen. Such map information includes
road network information, and also various facility information and
area information. Facilities to be displayed on a map include post
offices, convenience stores, and gas stations, for example. Areas
to be displayed include seas, parks, and city blocks, for example.
When the map information is displayed on a screen, the facilities
are displayed as "landmarks" represented by graphics, characters,
or a combination of both. The areas are defined by polygons.
Hereinafter, the landmarks and the areas included in the map
information are collectively referred to as "objects". Vehicle
navigation devices are intended to provide users with guidance to a
destination by appropriately displaying road network information
and object information both included in map information.
[0005] Conventional vehicle navigation devices display map
information as a plain view or a perspective view from the top.
Most of these devices display roads each as a line segment having a
negligible width, without reflecting their actual road widths. Such
display is hereinafter referred to as "zero-width display". For
vehicle navigation devices carrying out zero-width display, map
information is generated to support zero-width display. Therefore,
as shown in FIG. 27a, roads and objects can be simultaneously
displayed while almost keeping the actual positional relation
therebetween. Thus, there do not exist significant problems on a
display screen.
[0006] On the other hand, for better destination guidance to users,
some vehicle navigation devices may display each road with its own
road width. Such display is hereinafter referred to as "width
display". Such width display is adopted especially by vehicle
navigation devices carrying out three-dimensional display of roads
each provided with height. The reason is that displaying roads each
provided only with height causes a difficulty for users in
recognizing the shape of the roads. To reduce such difficulty,
width display is very effective. For width display, however,
enormous amount of data is required as the map information.
Therefore, the existing map information for zero-width display is
preferably used for width display without generating another map
information.
[0007] However, if the map information for zero-width display is
used for width display, the roads and objects may overlap each
other, as shown in FIG. 27b. In FIG. 27b, a landmark that
represents a post office and an area are displayed on a screen,
overlapping with a road with a road width. Such display screen is
quite awkward for users, who expect reality in road display.
[0008] One solution to the above problem is to generate another map
information dedicated to width display. However, such map
information is enormous in volume, as stated above, and therefore
the existing map information for zero-width display is preferably
used for generating new map information. Also, for devices capable
of switching between width display and zero-width display by user's
selection or capable of switching the road width to another one for
display, it is preferable that only single map information is
commonly used for every case without having plural map
information.
SUMMARY OF THE INVENTION
[0009] Therefore, an object of the present invention is to provide
a device and method for automatically changing position of an
object or a road on a map so that the object does not overlap with
the road displayed with a road width.
[0010] The present invention has the following features to achieve
the object above.
[0011] A first aspect of the present invention is directed to a map
information changing device for changing positions of landmarks and
areas included in map information, the device including: a map
information storage for storing the map information at least
related to roads, the landmarks, and the areas; an overlap
determination unit for determining whether the landmark and the
area included in the map information overlap with the road included
in the map information and displayed with a road width; a position
changer for changing positional information of the landmark and the
area determined by the overlap determination unit as overlapping
with one or more roads by moving each of the landmark and the area
to a position at which each of the landmark and the area does not
overlap with the one or more roads displayed with the road width,
while keeping each location side of the landmark and the area with
respect to a center line of each road; and a changed map
information storage for storing the map information and the
positional information of the landmark and the area changed by the
position changer.
[0012] In such map information changing device, the landmark and
the area are changed in position so as not to overlap with the
roads displayed with the road width, while keeping each location
side of the landmark and the area with respect to the center line
of each road. Therefore, when the map information is displayed on a
screen with the road width based on the original map information
and the changed positional information, the landmark and the area
are displayed so as not to overlap with the road. Thus, a realistic
screen can be presented to the user.
[0013] In this case, the position changer may move the landmark or
each vertex of the area away from the center line of each of the
one or more roads. To move each vertex of the area, the position
changer may deform the area in a direction away from the center
line of each of the one or more roads, or may translate the area
away from the center line of each of the one or more roads.
According to the area deforming method, the area is deformed to be
reduced in size. Such reduced area will not cause another overlap
with a road, and therefore only one process is enough for each
road. Consequently, it is possible to change the positional
information with small amount of calculation. On the other hand,
according to the area moving method, the area is moved as keeping
its shape. Therefore, it is possible to prevent the user from
erroneously recognizing the shape of the area.
[0014] According to a second aspect of the present invention, in
the first aspect, the map information changing device further
includes a map information display unit for displaying, on a
screen, the changed map information stored in the changed map
information storage with the road width. In such map information
changing device, the roads, landmarks and areas are displayed on a
screen based on the original map information and the changed
positional information. The landmark and the area are displayed so
as not to overlap with the road. Thus, a realistic screen can be
presented to the user.
[0015] In this case, the overlap determination unit and the
position change unit may switch the road width to another road
width based on an input from a user. Thus, even if the road width
is switched based on the selection by the user, the landmark and
the area are always displayed so as not to overlap with the roads.
Therefore, a realistic screen can be presented to the user without
requiring a plurality of map information provided in advance.
[0016] Furthermore, if the map information changing device equipped
with the map information display unit is incorporated in a
navigation device, the landmark and the area are displayed so as
not to overlap with the roads displayed with the road width.
Therefore, a realistic screen can be presented to the user.
[0017] A third aspect of the present invention is directed to a
method for changing positions of landmarks and areas included in
map information, the method including the steps of: storing the map
information at least related to roads, the landmarks, and the
areas; determining whether the landmark and the area included in
the map information overlap with the road included in the map
information and displayed with a road width; changing positional
information of the landmark and the area determined in the overlap
determining step as overlapping with one or more roads by moving
each of the landmark and the area to a position at which each of
the landmark and the area does not overlap with the one or more
roads displayed with the road width, while keeping a location side
of each of the landmark and the area with respect to a center line
of each road; and storing the map information and the positional
information of the landmark and the area changed in the positional
information changing step.
[0018] In such map information changing method, the landmark and
the area are changed in position so as not to overlap with the
roads displayed with the road width, while keeping each location
side of the landmark and the area with respect to the center line
of each road. Therefore, when the map information is displayed on a
screen with the road width based on the original map information
and the changed positional information, the landmark and the area
are displayed so as not to overlap with the road. Thus, a realistic
screen can be presented to the user.
[0019] In this case, in the positional information changing step,
the landmark or each vertex of the area may be moved away from the
center line of each of the one or more roads. To move each vertex
of the area, in the positional information changing step, the area
may be deformed in a direction away from the center line of each of
the one or more roads, or translated away from the center line of
each of the one or more roads. According to the area deforming
method, the area is deformed to be reduced in size. Such reduced
area will not cause another overlap with roads, and therefore only
one process is enough for each road. Consequently, it is possible
to change the positional information with small amount of
calculation. On the other hand, according to the area moving
method, the area is moved as keeping its shape. Therefore, it is
possible to prevent the user from erroneously recognizing the shape
of the area.
[0020] A fourth aspect of the present invention is directed to a
map information changing device for changing positions of roads
included in map information, the device including: a map
information storage for storing the map information at least
related to the roads, landmarks, and areas; an overlap
determination unit for determining whether the road included in the
map information and displayed with a road width overlaps with the
landmark and the area included in the map information; a position
changer for changing positional information of the road determined
by the overlap determination unit as overlapping with one or more
landmarks and areas by moving the road displayed with the road
width to a position at which the road does not overlap with the one
or more landmarks and areas, while keeping a location side of each
of the landmarks and the areas with respect to a center line of the
road; and a changed map information storage for storing the map
information and the positional information of the road changed by
the position changer.
[0021] In such map information changing device, the road displayed
with the road width is changed in position so as not to overlap
with the landmark and the area. Therefore, when the map information
is displayed on a screen with the road width based on the original
map information and the changed positional information, the road is
displayed so as not to overlap with the landmark and the area.
Thus, a realistic screen can be presented to the user.
[0022] In this case, the position changer may move each endpoint of
a segment composing the road away from the one or more landmarks
and areas. Alternatively, the position changer may translate the
road away from the one or more landmarks and areas. Also, the
position changer may move one endpoint of the segment composing the
road away from the one or more landmarks and areas. In either case,
the road displayed with the road width is changed in position so as
not to overlap with the landmark and the area. Therefore, when the
map information is displayed on a screen with the road width based
on the original map information and the changed positional
information, the road is displayed so as not to overlap with the
landmark and the area.
[0023] According to a fifth aspect of the present invention, in the
fourth aspect, the map information changing device further includes
a map information display unit for displaying, on a screen, the
changed map information stored in the changed map information
storage with the road width. In such map information changing
device, the road, landmark, and area are displayed on a screen,
based on the original map information and the changed positional
information. The road is displayed so as not to overlap with the
landmark and the area. Thus, a realistic screen can be presented to
the user.
[0024] In this case, the overlap determination unit and the
position changer may switch the road width to another road width
based on an input from a user. Consequently, even if the road width
is switched based on the selection by the user, the road is always
displayed so as not to overlap with the landmark and the area.
Therefore, a realistic screen can be presented to the user without
requiring a plurality of map information provided in advance.
[0025] Furthermore, if the map information changing device equipped
with the map information display unit is incorporated in a
navigation device, the roads displayed with the road width are
displayed so as not to overlap with the landmark and the area.
Therefore, a realistic screen can be presented to the user.
[0026] A sixth aspect of the present invention is directed to a
method for changing positions of roads included in map information,
the method including the steps of: storing the map information at
least related to the roads, landmarks, and areas; determining
whether the road included in the map information and displayed with
a road width overlaps with the landmark and the area included in
the map information; changing positional information of the road
determined in the overlap determining step as overlapping with one
or more landmarks and areas by moving the road displayed with the
road width to a position at which the road does not overlap with
the one or more landmarks and areas, while keeping a location side
of each of the landmarks and the areas with respect to a center
line of the road; and storing the map information and the
positional information of the road changed in the positional
information changing step.
[0027] In such map information changing method, the road displayed
with the road width is changed in position so as not to overlap
with the landmark and the area. Therefore, when the map information
is displayed on a screen with the road width based on the original
map information and the changed positional information, the road is
displayed so as not to overlap with the landmark and the area.
Thus, a realistic screen can be presented to the user.
[0028] In this case, in the positional information changing step,
each endpoint of a segment composing the road may be moved away
from the one or more landmarks and areas. Alternatively, the road
may be translated away from the one or more landmarks and areas.
Also, one endpoint of the segment composing the road may be moved
away from the one or more landmarks and areas. In either case, the
road displayed with the road width is changed in position so as not
to overlap with the landmark and the area. Therefore, when the map
information is displayed, based on the original map information and
the changed positional information, on a screen with the road width
provided thereto, the road is displayed so as not to overlap with
the landmark and the area.
[0029] 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
[0030] FIG. 1 is a block diagram showing the structure of a map
information changing device according to a first embodiment of the
present invention;
[0031] FIG. 2 is a block diagram showing the structure of an
overlap determination unit 11a of a map information changing device
1 shown in FIG. 1;
[0032] FIG. 3 is a flow chart showing the operation of the map
information changing device 1 shown in FIG. 1;
[0033] FIG. 4 is a diagram showing an example of a screen displayed
by using map information changed by the map information changing
device 1 shown in FIG. 1;
[0034] FIGS. 5a and 5b are diagrams in assistance of explaining the
operation of the overlap determination unit 11a of the map
information changing device 1 shown in FIG. 1;
[0035] FIGS. 6a and 6b are diagrams in assistance of explaining the
operation of a position changer 12a of the map information changing
device 1 shown in FIG. 1 for changing a landmark position;
[0036] FIGS. 7a and 7b are diagrams showing how to calculate a
deforming direction by the position changer 12a of the map
information changing device 1 shown in FIG. 1;
[0037] FIG. 8 is a diagram in assistance of explaining a distance
between a road and a line passing through each vertices of an area
in the position changer 12a of the map information changing device
1 shown in FIG. 1;
[0038] FIG. 9 is a diagram in assistance of explaining an area
position changing operation by deformation in the position changer
12a of the map information changing device 1 shown in FIG. 1;
[0039] FIG. 10 is a diagram in assistance of explaining an area
position changing operation by parallel translation in the position
changer 12a of the map information changing device 1 shown in FIG.
1;
[0040] FIG. 11 is a block diagram showing the structure of a map
information changing device according to a second embodiment of the
present invention;
[0041] FIG. 12 is a diagram showing how a landmark overlaps with
two roads;
[0042] FIG. 13 is a block diagram showing the structure of an
overlap determination unit 11b of a map information changing device
2 shown in FIG. 11;
[0043] FIG. 14 is a flow chart showing the operation of the map
information changing device 2 shown in FIG. 11;
[0044] FIG. 15 is a diagram showing how the position of the
landmark is gradually changed by the map information changing
device 2 shown in FIG. 11;
[0045] FIG. 16 is a block diagram showing the structure of a map
information changing device according to a third embodiment of the
present invention;
[0046] FIG. 17 is a block diagram showing the structure of an
overlap determination unit 11c of a map information changing device
3 shown in FIG. 16;
[0047] FIG. 18 is a flow chart showing the operation of the map
information changing device 3 shown in FIG. 16;
[0048] FIG. 19 is a diagram showing how the position of the
landmark is changed by the map information changing device 3 shown
in FIG. 16 with a plurality of roads considered at one time;
[0049] FIG. 20 is a block diagram showing the structure of a map
information changing device according to a fourth embodiment of the
present invention;
[0050] FIG. 21 is a block diagram showing the structure of an
overlap determination unit 11d of a map information changing device
4 shown in FIG. 20;
[0051] FIG. 22 is a flow chart showing the operation of the map
information changing device 4 shown in FIG. 20;
[0052] FIG. 23 is a block diagram showing the structure of a map
information display device according to a fifth embodiment of the
present invention;
[0053] FIG. 24 is a block diagram showing the-structure of a map
information display device according to a sixth embodiment of the
present invention;
[0054] FIG. 25 is a block diagram showing the structure of a map
information display device according to a seventh embodiment of the
present invention;
[0055] FIG. 26 is a block diagram showing the structure of a map
information display device according to an eighth embodiment of the
present invention; and
[0056] FIGS. 27a and 27b are diagrams each showing an example of a
display screen with the use of conventional map information.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0057] (First Embodiment)
[0058] FIG. 1 is a block diagram showing the structure of a map
information changing device 1 according to a first embodiment of
the present invention. A map information changing device 1
automatically converts map information for zero-width display into
the one for width display. The map information changing device 1
includes a map information storage 10, an overlap determination
unit 11a, a position changer 12a, and a changed map information
storage 13.
[0059] The map information storage 10 stores map information for
zero-width display including information on road network and
objects. For storing such map information, an arbitrary storage
medium such as a cassette tape, CD-ROM, DAT, DVD, semiconductor
memory, or IC memory (including RAM) is used. The map information
storage 10 may be a unit connecting to the Internet, for example,
and accessing to a remote storage medium.
[0060] As conventionally well known, in the road network
information included in the map information, data on road network,
intersections, and railroad network, and other data are represented
as a combination of nodes and links. The road network information
includes the number of road lanes and the number of railroad tracks
Such number information is used by a road width calculator 20,
which will be described later, for calculating the road width. For
objects (landmarks and areas), the map information includes
information on a position and attributes of each landmark, and
information on a position of each area. The landmark attribute
information is used by a size calculator 21, which will be
described later, for calculating the size of the landmark. The map
information may also include map information with various scales
such as 1/12,500, 1/25,000, 1/100,000, and 1/400,000.
[0061] FIG. 2 is a block diagram showing the structure of the
overlap determination unit 11a in more detail. As shown in FIG. 2,
the overlap determination unit 11a includes the road width
calculator 20, the size calculator 21, an overlap calculator 22,
and an output controller 23a.
[0062] The road width calculator 20 multiplies, for each road
included in road network information 30, the number of lanes by a
predetermined width for each lane. Based on the multiplication
result, the road width calculator 20 produces a road width W. Here,
the road width W is defined to be a distance between the center
line of a road and one edge thereof. If the number of lanes is not
given, the road width is assumed to be equal to the width of one
lane. If the map information includes attribute information for a
road, the width of the road not provided with the information of
the number of lanes may be given based on that attribute
information. For example, a road whose attribute indicates
"highway" is given "2 lanes", while a road whose attribute
indicates "private road" is given "1 lane".
[0063] The size calculator 21 calculates a size of each object,
based on the attribute information included in object information
31. In the present embodiment, landmarks are treated as a circle
with a radius L, while areas are as having a boundary line of 0
width. The size calculator 21 outputs the size L predetermined for
each type of landmarks or the value 0 for each area.
[0064] The overlap calculator 22 receives the road network
information 30 and the object information 31, and also the road
width W calculated by the road width calculator 20 and the size L
of the object calculated by the size calculator 21. The overlap
calculator 22 calculates a distance D between the road and the
object by using their positional information, which will be
described later. Then, the overlap calculator 22 determines, based
on the road width W, the size L, and the distance D, whether the
road and the object overlap or not, and then produces a
determination signal 40 indicating a determination result.
[0065] The output controller 23a is provided with the road network
information 30, the object information 31, and the determination
signal 40. Based on the determination signal 40, the output
controller 23a selectively produces outputs as follows. That is, if
the determination signal 40 indicates the object and the road
overlap each other, the output controller 23a outputs position
change information 33 including the positional information of the
overlapping road and the object information 31. If otherwise, the
output controller 23a outputs the object information 31 as it is as
the object information 32.
[0066] The position changer 12a changes, based on the received
position change information 33, the position of the object on the
map to resolve the overlap between the object and the road. Then,
the position changer 12a produces changed object information
34.
[0067] The changed map information storage 13 stores the road
network information 30, the object information 32 provided by the
overlap determination unit 11a, and the object information 34
provided by the position changer 12a. Composed of these information
is the map information for width display. To store such map
information, an arbitrary storage medium such as a cassette tape,
CD-ROM, DAT, DVD, semiconductor memory or IC memory (including RAM)
is used. The changed map information storage 13 may be a unit
connecting to the Internet, for example, and accessing to a remote
storage medium.
[0068] The map information changing device 1 detects a road
overlapping with a specific object, and then changes the object
position. With reference to a flow chart shown in FIG. 3, the
operation of the map information changing device (hereinafter
simply referred to as "device") 1 carried out on a specific object
is described. The device 1 selects an object from the map
information for zero-width display stored in the map information
storage 10 (step S101). Then, the device 1 selects a road (step
S102). Then, the device 1 determines, by the overlap determination
unit 11a, whether the selected object and road overlap each other
or not (step S103) If they overlap each other, the procedure goes
to step S104, and goes to step S106 if otherwise.
[0069] If determining instep S103 that they overlap each other, the
device 1 calculates, by using the position changer 12a, the changed
object information 34 (step S104). Then, the device 1 writes the
changed object information 34 in the changed map information
storage 13 (step S105). The process on the selected object is now
completed.
[0070] If determining in step S103 that the object and the road do
not overlap each other, the device 1 determines whether all roads
have been processed or not (step S106). If any road has been
unprocessed, the procedure returns to step S102. If all roads have
been processed, it is determined that the selected object does not
overlap with any roads. Therefore, the device 1 writes the object
information 31 as it is in the changed map information storage 13
(step S107). The process on the selected object is now
completed.
[0071] Thus obtained map information is used as the one for width
display by a map information display device (not shown) in a
vehicle navigation device, for example. In this map information,
the objects are changed in position so as not to overlap with any
roads on width display. Therefore, as shown in FIG. 4, the vehicle
navigation device using this map information can display the
objects so that they do not overlap with any roads, and thus can
present a realistic screen to the user.
[0072] The operation of the overlap calculator 22 is described
below in detail. First, with reference to FIG. 5a, how to find an
overlap between a landmark and a road is described. The overlap
calculator 22 assumes each landmark as a circle with the radius L,
and then calculates the distance D between a center point of a
specific landmark and a segment PQ forming a specific road. When
the center point of the landmark is A(A.sub.x, A.sub.y) , and
endpoints of the segment PQ are P(P.sub.x, P.sub.y) and Q(Q.sub.x,
Q.sub.y) , a point R on the segment PQ is represented as R=P+t
(Q-P) , where a parameter t satisfies 0.ltoreq.t.ltoreq.1. Thus,
each component of the vector from the point R to the point A is
represented by the following equation (1). 1 A - R = A - { P + t (
Q - P ) } = ( Ax Ay ) - { ( 1 - t ) ( Px Py ) + t ( Qx Qy ) } = (
Ax + ( t - 1 ) Px - tQx Ay + ( t - 1 ) Py - tQy ) ( 1 )
[0073] Therefore, the distance D between the landmark and the road
is a minimum value of the distance between the points A and R, that
is, a minimum value of a distance D1 defined in the following
equation (2),
D1={square root}{square root over
({Ax+(t-1)Px-tQx}.sup.2+{Ay+(t-1)Py-tQy}- .sup.2 )} (2)
[0074] where 0.ltoreq.t.ltoreq.1.
[0075] The distance D can be found by differentiating a square of
the distance D1 defined by the above equation (2), or by
calculating a distance between a point and a line or between two
points, based on the knowledge of a geometrical characteristic of
two-dimensional graphics.
[0076] By referring to the road width W calculated by the road
width calculator 20, the size L of the landmark calculated by the
size calculator 21, and the distance D calculated in the above
manner, the overlap calculator 22 determines as "overlap" if
D<L+W, and "not overlap" if D.gtoreq.L+W.
[0077] Next, with reference to FIG. 5b, how to determine an overlap
between an area and a road is described. Each area is defined as a
polygon having n segments L.sub.1, L.sub.2, . . . , L.sub.n as its
sides. The overlap calculator 22 first calculates a distance
D.sub.1 between each segment L.sub.1 and the segment PQ composing
the road. When endpoints of the i-th segment L.sub.1 are
S.sub.1(S.sub.1x, S.sub.1y) and E.sub.1 (E.sub.1x, E.sub.1y), a
point B on the segment L.sub.1 is represented as
B.sub.1=S.sub.1+u.sub.1(E.sub.1-S.sub.1), where a parameter u.sub.1
satisfies 0 .ltoreq.u.sub.1 .ltoreq.1. Also, the point R on the
segment PQ is represented as R=P+t(Q-P), where the parameter t
satisfies 0.ltoreq.t.ltoreq.1. Thus, each component of the vector
from the point R to the point B.sub.1 is represented by the
following equation (3). 2 Bi - R = { Si + ui ( Ei - Si ) } - { P +
t ( Q - P ) } = { ( 1 - ui ) ( Six Siy ) + ui ( Eix Eiy ) } - { ( 1
- t ) ( Px Py ) + t ( Qx Qy ) } = ( ( 1 - ui ) Six + uiEix + ( t -
1 ) Px - tQx ( 1 - ui ) Siy + uiEiy + ( t - 1 ) Py - tQy ) ( 3
)
[0078] Therefore, the distance D.sub.1 between the segment L.sub.1
and the road is a minimum value of the distance between the points
B.sub.1 and R, that is, a minimum value of a distance D2.sub.1
defined in the following equation (4),
D2i={square root}{square root over (Dix.sup.2+Diy.sup.2)} (4)
[0079] WHERE,
Dix=(1-ui)Six+uiEix+(t-1)Px-tQx
Diy=(1-ui)Siy+uiEiy+(t-1)Py-tQy
[0080] where 0.ltoreq.u.sub.1.ltoreq.1 and 0.ltoreq.t.ltoreq.1.
[0081] The distance D.sub.1 can be found by carrying out partial 15
differentiation on the square of the distance D2.sub.1 defined by
the above equation (4) with respect to the parameters u.sub.i and
t. Based on the knowledge of a geometrical characteristic of
two-dimensional graphics, the distance D.sub.1 can also be found by
determining whether two segments cross each other or not, and then
calculating a distance between a point and a line or between two
points.
[0082] The overlap calculator 22 calculates the distance D.sub.1
between every segment L.sub.1 and the road, and then finds a
minimum value M of the calculated distance D.sub.1. The overlap
calculator 22 compares the road width W calculated by the road
width calculator 20 with the minimum value M of the distance
D.sub.1, and determines as "overlap" if M<W, and "not overlap"
if M.gtoreq.W.
[0083] Next, the operation of the position changer 12a is
described. The position changer 12a changes the position of the
object determined as "overlap" by the overlap determination unit
11a so as to resolve the overlap between the object and the road.
This change is carried out based on the position change information
33 composed of the positional information of that road and the
object information 31. Described below is how to resolve an
overlap.
[0084] First, with reference to FIGS. 6a and 6b, how to resolve an
overlap between a landmark and a road is described. As shown in
FIG. 6a, a point R is a foot of a perpendicular dropped from the
center point A of a specific landmark to a line that connects the
points P and Q, and L.sub.v is a ray extending from the point R
through the point A. The position changer 12a arbitrarily selects a
point A.sub.c on the ray L.sub.v so that a distance from the point
R is not less than (L+W), and changes the center point A of the
landmark to the point A.sub.c. FIG. 6b is a diagram showing a state
in which the position changer 12 selects a point so that the
distance from the point R becomes (L+W) . As such, the landmark can
be changed in position so as not to overlap with the road, while
keeping its location side with respect to the center line of the
road.
[0085] Next, with respect to FIGS. 7a, 7b, and 8 through 10, how to
resolve an overlap between an area and a road is described. The
position changer 12a changes positional information of vertices of
a specific area through the following three steps. Note that, in
the following description on the three steps, a road defined by the
segment PQ is to be processed, a line going through the two points
P and Q is represented as L.sub.PQ, and each vertex of the area is
as S.sub.1.
[0086] In the first step, a direction V.sub.t in which the area
should be deformed (hereinafter referred to as deforming direction)
is calculated (refer to FIGS. 7a and 7b) The deforming direction
V.sub.t is either one of two direction perpendicular to the line
L.sub.PQ. The position changer 12a calculates a barycenter G of the
area (FIG. 7a), or a center C of a circle circumscribed about the
area (FIG. 7b). Of the two directions perpendicular to the line
L.sub.PQ, a direction from the line L.sub.PQ toward the barycenter
G or the center C is taken as the deforming direction V.sub.t.
[0087] In the second step, a deforming coefficient K for use in
deforming the area is calculated (refer to FIG. 8). Here, consider
a set of lines going through each vertex S.sub.i and parallel to
the line L.sub.PQ. Of this set of lines, a line that is located in
the deforming direction V.sub.t with respect to the line L.sub.PQ
and has a maximum distance therefrom is referred to as a line
L.sub.a. Also, of this set, a line that has a maximum distance from
the line L.sub.a is referred to as L.sub.b, and a line located in
the deforming direction V.sub.t with respect to the line L.sub.PQ
and at a distance equal to the road width W therefrom is referred
to as a line L.sub.c. When a distance between the line L.sub.PQ and
the line L.sub.a is D.sub.a and a distance between the line L.sub.a
and the line L.sub.b is D.sub.b, the deforming coefficient K is
calculated, based on the above distances and the road width W, as
K=(D.sub.a-W)/D.sub.b. The calculated deforming coefficient K
satisfies 0.ltoreq.K.ltoreq.1.
[0088] In the third step, the position of each vertex S.sub.1 is
changed in the deforming direction V.sub.t so that the distance to
the line L.sub.a becomes K-fold (refer to FIG. 9). That is, when a
foot of a perpendicular dropped from the point S.sub.i to the line
L.sub.a is T.sub.i, each vertex S.sub.1 is changed to a point
S.sub.1C internally dividing a segment T.sub.1S.sub.1 in the ratio
of K:(1-K). With this change, the area originally located between
the two lines L.sub.a and L.sub.b is deformed by a factor of K in
the deforming direction V.sub.t, and located between the two lines
L.sub.a and L.sub.c.
[0089] Through the first to third steps, the area is deformed by a
factor of K (0=K.ltoreq.1) in the direction perpendicular to the
line L.sub.PQ and away therefrom. As such, the positions of all
vertices of the area are changed so that they lie on the opposite
side of the line L.sub.PQ with reference to the line L.sub.c. Thus,
the area no longer overlaps with the road on width display. Thus,
through the first to third steps, the area can be changed in
position so as not to overlap with the road, while keeping its
location side with respect to the center line of the road.
[0090] Alternatively, similarly to the case of landmark change, the
position changer 12a may move every vertex S.sub.1 of the area
along the deforming direction V.sub.t by an arbitrary distance not
less than (D.sub.b-D.sub.a+W) . This movement is shown in FIG. 10.
Also with this, the positions of all vertices of the area are
changed so that they lie on the opposite side of the line L.sub.PQ
with reference to the line L.sub.c. Therefore, the area can be
changed in position so as not to overlap with the road, while
keeping its location side with respect to the center line of the
road. Moreover, the position changer 12a may change the area in
position by combining the above-described two techniques,
vertex-moving and area-deforming techniques, together.
[0091] As stated above, according to the present embodiment,
whether a specific object and a specific road both included in the
map information overlap each other or not when they are on width
display is first determined. Then, the overlapping object is
changed in position so as not to overlap with the road, while
keeping its location side with respect to the center line of the
road. Therefore, when the map information generated by the map
information changing device according to the present embodiment is
displayed with road width, every object is displayed so as not to
overlap with any road, and a realistic screen is presented to the
users.
[0092] The changed map information storage 13 according to the
present embodiment stores the entire map information for width
display. Alternatively, the changed map information storage 13 may
store only the object information 34 received from the position
changer 12a. Such partial map information is used simultaneously
with the existing map information for zero-width display.
[0093] (Second Embodiment)
[0094] FIG. 11 is a block diagram showing the structure of a map
information changing device 2 according to a second embodiment of
the present invention. This map information changing device 2
automatically converts the map information for zero-width display
into the one for width display, as in the first embodiment. The map
information changing device 2 includes the map information storage
10, an overlap determination unit 11b, the position changer 12a,
and the changed map information storage 13 The components identical
in structure to those in the first embodiment are provided with the
same reference numerals, and not described herein.
[0095] In the map information, an object may overlap with a
plurality of roads on width display, as shown in FIG. 12. In FIG.
12, a landmark is represented as a circle with a radius L centering
at a point A.sub.1 and an i-th (i is an integer where
1.ltoreq.i.ltoreq.4) road is as a rectangle composed by providing a
segment PQ, with a road width W.sub.1. When a distance between the
i-th road and the point A is a distance D.sub.1, if
D.sub.1.ltoreq.L+W.sub.1 and D.sub.2.ltoreq.L+W.sub.2, the landmark
overlaps with two roads, first and second. Such object overlapping
with a plurality of roads can be often observed in the vicinity of
an intersection of roads.
[0096] In the first embodiment, it is assumed that an object
possibly overlaps with a single road, at most. Therefore, the
positional information of the object is changed only once, at most.
On the other hand, in the present embodiment, it is assumed that an
object possibly overlaps with a plurality of roads. Therefore, the
positional information of the object may be changed repeatedly.
[0097] FIG. 13 is a block diagram showing the structure of the
overlap determination unit 11b in more detail. As shown in FIG. 13,
the overlap determination unit 11b includes the road width
calculator 20, the size calculator 21, the overlap calculator 22,
an output controller 23b, and a positional information replacing
unit 24. Of these components, the road width calculator 20, the
size calculator 21, and the overlap calculator 22 operate similarly
to those in the first embodiment.
[0098] The positional information replacing unit 24 replaces the
positional information included in the object information 31 with
the positional information included in the changed object
information 34, and then outputs positional information after
replacement 41. At an initial state, however, the changed object
information 34 is not yet provided, and therefore the positional
information replacing unit 24 outputs the object information 31 as
it is as the object information after replacement 41.
[0099] The output controller 23b is provided with the road network
information 30, the object information 41, and the determination
signal 40. Based on the determination signal 40, the output
controller 23b selectively produces outputs as follows. That is, if
the determination signal 40 indicates the object and the road
overlap each other, the output controller 23b outputs the position
change information 33 including the positional information of the
overlapping road and the object information after replacement 41.
If the determination signal 40 indicates that the object does not
overlap with any roads after changed in position repeatedly, the
output controller 23b outputs the object information 41 after
replacement as object information 35.
[0100] The map information changing device 2 repeatedly changes the
object in position until the object does not overlap with any roads
on width display. With reference to a flow chart shown in FIG. 14,
the operation of the map information changing device (hereinafter
simply referred to as "device") 2 on a single object is now
described. First, the device 2 selects an object and a road to be
processed, as in the first embodiment (steps S201 and S202). Then,
the device 2 determines by using the overlap determination unit 11b
whether the selected object and road overlap each other or not
(step S203). If they overlap each other, the procedure goes to step
S204, and goes to step S206 if otherwise.
[0101] If it is determined in step S203 that they overlap each
other, the device 2 calculates, by the position changer 12a, the
changed object information 34 (step S204). The changed object
information 34 is used for overlap determination in step S203 and
thereafter. Then, the device 2 sets all roads to be "unprocessed"
(step S205). The procedure then returns to step S202. Thus, overlap
determination in step S203 is repeatedly carried out on every
road.
[0102] If determining in step S203 that the object and the road do
not overlap each other, the device 2 determines whether all roads
have been processed (step S206). If any road has been unprocessed,
the procedure returns to step S202. If all roads have been
processed, it is determined that the selected object does not
overlap with any roads. Therefore, the device 2 writes the object
information 41 after replacement in the changed map information
storage 13 (step S207). The process on the selected object is now
completed.
[0103] FIG. 15 is a diagram showing how the landmark shown in FIG.
12 is gradually changed in position by the device 2. When an
initial position of the landmark is a point A, the device 2 changes
the landmark in position so that the landmark does not overlap with
the first road defined by the segment PQ.sub.1 , and then with the
second road defined by a segment PQ.sub.2. Such changing process is
now described below.
[0104] The device 2 detects, by the overlap determination 11b,
whether there is a road overlapping with the landmark. Here, the
device 2 detects that the first road overlaps with the landmark,
and then changes the landmark in position so that the landmark does
not overlap with the first road. That is, the position changer 12a
of the device 2 moves the landmark to a point A.sub.1 shown in FIG.
15.
[0105] Then, the device 2 detects whether there is another road
overlapping with the landmark by using the object information 34
indicating that the landmark position has changed to the point
A.sub.1. Here, the device 2 detects that the second road overlaps
with the landmark, and then changes the landmark in position so
that the landmark does not overlap with the second road. That is,
the position changer 12a of the device 2 moves the landmark to a
point A.sub.2 shown in FIG. 15.
[0106] Then, the device 2 detects whether there is still another
road overlapping with the landmark. Here, none of the roads
overlaps with the landmark. Therefore, the device 2 writes, in the
changed map information storage 13, the object information 34
indicating that the landmark position has changed to the point
A.sub.2.
[0107] As such, the device 2 uses the positional information
replacing unit 24 to replace the positional information included in
the object information with the changed one, thereby repeatedly
changing the landmark in position. Thus, any overlapping road can
be sequentially detected, and the landmark can be gradually changed
in position so as not to overlap with the roads.
[0108] Furthermore, the position changer 12a can change the
position of an area with respect to a single road by deforming or
moving the area. Therefore, the device 2 repeatedly changes the
position of the area overlapping with a plurality of roads so that
the area gradually moves away from the road.
[0109] As state above, according to the present embodiment, the
object is changed in position so as not to overlap with a single
road on width display. If the object still overlaps with another
road on width display, the object is further changed in position so
as not to overlap that road. As such, the object is changed in
position repeatedly, and finally to a position so as not to overlap
with any roads. Therefore, when the map information generated by
the map information changing device according to the present
embodiment is on width display, every object is displayed so as not
to overlap with any road, and a realistic screen is presented to
users.
[0110] Furthermore, according to the present embodiment, an object
overlapping with a plurality of roads can be changed in position.
Also, a potential overlap can be resolved. Here, the potential
overlap is an overlap that may newly occur, due to a change made
for resolving an overlap between an object and one road, between
that object and another road. In the first embodiment, the position
of the object is changed once at most, and therefore the generated
map information for width display may possibly include the
above-stated potential overlaps. On the other hand, in the present
embodiment, the position of the object is changed repeatedly, and
therefore the generated map information for width display does not
include potential overlaps.
[0111] Depending on the characteristics of the map information for
zero-width display, there exist some possibilities that not all
overlaps can be resolved even by repeatedly changing each object in
position. In consideration of such possibilities, the number of
times for changing the position may be limited. In this case, if
the object cannot be changed in position so as not to overlap with
any roads even after a predetermined number of changes, the device
2 writes, in the changed map information storage 13, the positional
information at this moment or originally provided.
[0112] (Third Embodiment)
[0113] FIG. 16 is a block diagram showing the structure of a map
information changing device 3 according to a third embodiment of
the present invention. This map information changing device 3
automatically converts the map information for zero-width display
into the one for width display, as in the first embodiment. The map
information changing device 3 includes the map information storage
10, an overlap determination unit 11c, a position changer 12c, the
changed map information storage 13, and a temporary storage 16. The
components identical in structure to those in the first embodiment
are provided with the same reference numerals, and not described
herein.
[0114] In the present embodiment, similarly to the second
embodiment, a case where an object overlaps with a plurality of
roads is considered. In the second embodiment, every time an
overlapping road is detected, the object is changed in position so
as not to overlap with that road. On the other hand, in the present
embodiment, every time an overlapping road is detected, its
positional information is temporarily stored. Then, the object is
changed in position in one process so as not to overlap with all of
the detected roads.
[0115] The temporary storage 16 stores the positional information
of the road determined by the overlap determination unit 11c as
overlapping with the object. In consideration of all roads
determined by the overlap determination unit 11c as overlapping
with the object, the position changer 12c changes the object in
position in one process so that the object does not overlap with
any of these roads. The operation of the position changer 12c will
be described later in detail.
[0116] FIG. 17 is a block diagram showing the structure of the
overlap determination unit 11c in more detail. As shown in FIG. 17,
the overlap determination unit 11c includes the road width
calculator 20, the size calculator 21, the overlap calculator 22,
and an output controller 23c. Of these components, the road width
calculator 20, the size calculator 21, and the overlap calculator
22 operate similarly to those in the first embodiment.
[0117] The output controller 23c is provided with the road network
information 30, the object information 31, and the determination
signal 40. Based on the determination signal 40, the output
controller 23c selectively produces outputs as follows. That is, if
the determination signal 40 indicates the object and the road
overlap each other, the output controller 23c outputs the
positional information of the road determined as overlapping as
road positional information 36 to be stored in the temporary
storage 16. If the determination signal 40 indicates that they do
not overlap each other, the output controller 23c ignores the
positional information on that road. After overlap determination
has been made over all the roads, the output controller 23c reads
the road positional information 36 from the temporary storage 16.
Then, the output controller 23c outputs the read road positional
information 36 and the object information 31 as position change
information 37. If no road positional information 36 is stored in
the temporary storage 16 at all, the output controller 23c outputs
the object information 31 as it is as the object information 32 to
be stored.
[0118] The map information changing device 3 sequentially detects a
road overlapping with a specific object, temporarily stores the
positional information thereof, and changes the object in position
in one process so that the object does not overlap with any of the
stored roads. With reference to FIG. 18, described is the operation
of the map information changing device (hereinafter simply referred
to as"device") 3 on a single object. First, the device 3 selects an
object and a road to be processed, as in the first embodiment
(steps S301 and S302). Then, the device 3 determines by the overlap
determination unit 11c whether the selected object and road overlap
each other or not (step S303) If they overlap each other, the
device 3 stores the positional information of the selected road in
the temporary storage 16 (step S304). The device 3 repeats the
process from steps S302 to S304 on every road (step S305).
[0119] Then, the device 3 determines whether the positional
information of the selected road is stored in the temporary storage
16 (step S306). If determining in step S306 that such positional
information is stored, the device 3 calculates, by using the
position changer 12c, changed object information 38 (step S307),
and stores the changed object information 38 in the changed map
information storage 13 (step S308). The process on the selected
object is now completed If determining in step S306 that the
positional information is not stored, the device 3 writes the
object information 31 as it is in the changed map information
storage 13 (step S309). The process on the selected object is now
completed.
[0120] Next, the operation of the position changer 12c is
described. The position changer 12c changes the position of the
object determined as "overlap" by the overlap determination unit
11c so as to resolve the overlaps with every road. This change is
carried out based on the position change information 37 composed of
the road positional information 36 and the object information 31.
Described below is how to resolve overlaps between the object with
a plurality of roads in one process.
[0121] First, with reference to FIG. 19, how to resolve overlaps
between a landmark and a plurality of roads in one process is
described. It is assumed herein that the landmark overlaps with n
roads on width display, and an i-th (i is an integer where
1.ltoreq.i.ltoreq.n) road is defined by a segment P.sub.1Q.sub.1.
Note that FIG. 19 shows an example where n=2.
[0122] In a first step, a vector V representing a direction in
which the landmark should be moved is calculated. Assuming that a
point R.sub.1 is a foot of a perpendicular dropped from the center
point A of the landmark to a line going through the two points
P.sub.i and Q.sub.1, the position changer 12c calculates, for each
road, a vector V.sub.1 from the point R.sub.1to the point A. Then
position changer 12c finds a unit vector in the direction of each
vector V.sub.1, and takes a sum of the found unit vectors as the
vector V. In other words, the vector V is calculated by the
following equations (5) and (6),
V.sub.1=A-R.sub.i (5)
V=.SIGMA.(V.sub.i/.vertline.V.sub.1.vertline.) (i=1 to n) (6)
[0123] where .vertline.V.sub.i.vertline. is the magnitude of the
vector V.sub.1, and .SIGMA. represents addition of the vectors.
[0124] In a second step, the amount of movement of the landmark in
the direction of the vector V is calculated for resolving overlaps
with the plurality of roads. The landmark is moved to a position
A.sub.c represented by A.sub.c=A+x V, where a parameter x satisfies
x>0. The position changer 12c calculates an angle .THETA. formed
by each vector V.sub.1 and the vector V, and then finds the range
of x.sub.1 that satisfies the following equation (7) for each
i.
.vertline.x.sub.1V.vertline. cos
.THETA..sub.1.gtoreq.L+W.sub.1-D.sub.1 (7)
[0125] If x.sub.1 that satisfies the above equation (7) is selected
and the landmark is moved in the direction of the vector V, an
overlap between the landmark and the i-th road can be resolved.
Therefore, if x that satisfies the above equation (7) is selected
for every i satisfying 1.ltoreq.i.ltoreq.n, the amount of movement
required for resolving overlaps with every road can be
calculated.
[0126] As such, the direction and the amount of movement of the
landmark are calculated in the first and second steps,
respectively. Thus, the landmark is moved to the position A.sub.c
so as not to overlap with any road.
[0127] If the angle .THETA..sub.1 is not less than .rho./2, the
left side of the above equation (7) becomes negative, while the
right side thereof becomes positive. Thus, x.sub.1 that satisfies
the above equation (7) does not exist. Therefore, the overlap
between the landmark and the i-th road can not be resolved even if
the landmark is moved in the direction of the vector V. In this
case, the position changer 12c may output the positional
information of the landmark as it is without any change.
Alternatively, the position changer 12c may execute the first and
second steps after excluding any road whose angle .THETA..sub.1
becomes not less than .pi./2. By adopting the former method,
overlaps with roads cannot be resolved at all, but by adopting the
latter method, some overlaps can be resolved.
[0128] Next, how to resolve overlaps between an area and roads in
one process is described. The position changer 12a according to the
first embodiment resolves an overlap between the area and a single
road by deforming or moving the area. The position changer 12c
according to the present embodiment resolves an overlap with an
area and a single road by using the area-deforming or area-moving
techniques stated in the first embodiment. If the area overlaps
with a plurality of roads, the position changer 12c moves the area
in a manner as stated below, thereby resolving such overlaps.
[0129] First, the position changer 12c calculates a deforming
direction of the area with respect to each road in the manner as
that shown in the first embodiment. Then, the position changer 12c
adopts a processing composed of the first and second steps adopted
to each landmark for changing each vertex thereof, where the
calculated deforming direction is taken as the vector V.sub.1 for
the landmark. Here, the parameter x is selected so as to satisfy
the above equation (7) with respect to every vertices of that area
and every road thereof. By using the direction and amount of
movement, the area is moved in a manner similar to that in the
first embodiment. Thus, overlaps between the area and the plurality
of roads can be resolved in one process.
[0130] The above method is equivalent to a method in which an area
is taken as a landmark having a center point A, which is either a
center C or a barycenter G of a circle circumscribed about an area
and having a maximum value L of a distance between the center point
A and each vertex of the area, and the center point of the landmark
is moved so that the landmark does not overlap with the plurality
of roads.
[0131] As described above, according to the present embodiment,
whether the object included in the map information overlaps with a
plurality of roads included in the map information on width display
is first determined. If the object overlaps with the plurality of
roads, the object is moved, in one process, to a position not
overlapping with the plurality of roads on width display, while
keeping its location side with respect to the center line of the
road. Thus, when the map information generated by the map
information changing device of the present embodiment is displayed
with road width so that the objects do not overlap the roads, and a
realistic screen can be presented to the user.
[0132] (Fourth Embodiment)
[0133] FIG. 20 is a block diagram showing the structure of a map
information changing device 4 according to a fourth embodiment of
the present invention. The map information changing device 4
automatically converts the map information for zero-width display
into the one for width display, as in the first embodiment. The map
information changing device 4 includes the map information storage
10, a overlap determination unit 11d, the position changer 12c, the
changed map information storage 13, and the temporary storage 16.
The present invention is characterized in that the object is
gradually changed in position, as in the second embodiment, and
that in consideration of a plurality of overlaps with roads, the
object is changed in position in one process as in the third
embodiment. In the present embodiment, the components identical in
structure to those in the first through third embodiments are
provided with the same reference numerals, and not described
herein.
[0134] FIG. 21 is a block diagram showing the structure of the
overlap determination unit lid in more detail. As shown in FIG. 21,
the overlap determination unit 11d includes the road width
calculator 20, the size calculator 21, the overlap calculator 22,
an output controller 23d, and a positional information replacing
unit 24. Of these components, the road width calculator 20, the
size calculator 21, the overlap calculator 22, and the positional
information replacing unit 24 operate similarly to those in the
first or second embodiment.
[0135] The output controller 23d is provided with the road network
information 30, the object information 41, and the determination
signal 40. Based on the determination signal 40, the output
controller 23d selectively produces outputs as follows. That is, if
the determination signal 40 indicates the object and the road
overlap each other, the output controller 23d outputs the
positional information of the road determined as overlapping as
road positional information 36 to be stored in the temporary
storage 16. If the determination signal 40 indicates that they do
not overlap each other, the output controller 23d ignores the
positional information of that road. After overlap determination
has been made over all the roads, the output controller 23d reads
the road positional information 36 from the temporary storage 16.
Then, the output controller 23d outputs the read road positional
information 36 and the object information 41 after replacement as
position change information 37. If no road positional information
36 is stored in the temporary storage 16 at all, the output
controller 23d outputs the object information 41 after replacement
as it is as object information 39 to be stored.
[0136] The map information changing device 4 sequentially detects a
road overlapping with an object, temporarily stores the positional
information thereof, and changes the object in position in one
process so that the object does not overlap with any stored roads.
These detecting and changing processes are repeatedly carried out.
With reference to a flow chart shown in FIG. 22, described is the
operation of the map information changing device (hereinafter
simply referred to as "device") 4 on a single object. First, the
device 4 selects an object to be processed, as in the third
embodiment (step S401), and then stores the positional information
of a road that overlaps with the selected object in the temporary
storage 16 (steps S402 to S405).
[0137] Then, the device 4 determines whether the positional
information of the road(s) is stored in the temporary storage 16
(step S406). If determining in step S406 that such positional
information is stored, the device 4 calculates, by using the
position changer 12c, the changed object information 38 (step
S407). Then, the device 4 sets all roads to be "unprocessed" (step
S408), and clears the road positional information stored in the
temporary storage 16 (step S409). Then, the procedure returns to
step S402. Therefore, overlap determination in step S403 can be
carried out on all roads repeatedly.
[0138] If determining in step S406 that the positional information
is not stored, it is determined that the object has been moved to a
position so as not to overlap with any roads. Therefore, the device
4 writes the object information 41 after replacement in the changed
map information storage 13 (step S410). Thus, the process on the
selected object is now completed.
[0139] As stated above, according to the present embodiment, the
positional information of the object is changed in one process in
consideration of overlaps with a plurality of roads, and also the
object is gradually moved repeatedly until overlaps with all roads
can be resolved. Therefore, the present embodiment has the
characteristics of both the second and third embodiments, as stated
above. Thus, when the map information generated by the map
information changing device of the present embodiment is displayed
with road width so that the objects do not overlap the roads, and a
realistic screen can be presented to the user.
[0140] (Fifth Embodiment)
[0141] FIG. 23 is a block diagram showing the structure of a map
information display device 5 according to a fifth embodiment of the
present invention. A map information display device 5 automatically
converts the map information for zero-width display into the one
for width display and displays the converted map information, and
is used as being incorporated into a vehicle navigation device or
the like, for example. The map information display device 5
includes the map information changer 10, the overlap determination
unit 11a, the position changer 12a, the changed map information
storage 13, a command input unit 14, and a map information display
unit 15. In the present embodiment, components identical in
structure to those in the first embodiment are provided with the
same reference numerals, and not described again herein.
[0142] The command input unit 14 outputs width information 50 in
response to an instruction from a user. The width information 50
indicates 0 if the user makes a "zero-width display" instruction,
and indicates the predetermined road width W if the user makes a
"width display" instruction. If the user makes an "enhanced width
display" instruction for enhancing the width on display, the width
information 50 indicates a width wider than the predetermined width
W, for example, a doubled width (2.times.W) . The width information
50 is provided to the overlap determination unit 11a, the position
changer 12a, and the map information display unit 15. The overlap
determination unit 11a and the position changer 12a refer to the
width information to carry out processing as that in the first
embodiment.
[0143] The map information display unit 15 receives the width
information 50 and the changed map information 51 stored in the
changed map information storage 13. The map information display
unit 15 is equipped with a display such as a CRT, liquid crystal
display, TV, plasma display, or hologram display. Based on the
received map information, the map information display unit 15
displays the roads, landmarks, and areas simultaneously on a
screen. At this time, the roads are displayed with width as
required based on the width information 50.
[0144] As stated above, according to the present embodiment,
whether the object included in the map information overlaps with a
road on width display included in the map information is first
determined. If the object overlaps with the road, the object is
moved to a position at which the object does not overlap with the
road on width display, while keeping its location side with respect
to the center line of the road. Also, based on the original map
information and the changed positional information, the roads,
landmarks, and areas are simultaneously on width display. Thus, the
objects are displayed so as not to overlap with the roads, and a
realistic screen can be presented to the user.
[0145] Furthermore, according to the present embodiment, means for
changing map information and means for displaying the changed map
information are provided. Therefore, even if various widths are
switched for display based on the selection by the user, the
objects are always displayed so as not to overlap with the roads
without requiring a plurality of map information provided in
advance.
[0146] (Sixth Embodiment)
[0147] FIG. 24 is a block diagram showing the structure of a map
information display device 6 according to a sixth embodiment of the
present invention. This map information display device 6
automatically converts map information for zero-width display into
the one for width display and displays the converted map
information, as in the fifth embodiment, and is used as being
incorporated into a vehicle navigation device, for example. The map
information display device 6 is constructed by adding the command
input unit 14 and the map information display unit 15 to the map
information changing device 2 according to the second embodiment.
Therefore, the map information display device 6 has the same
characteristics as those according to the second and fifth
embodiments. The details on the map information display device 6
are thus evident from the above description of these embodiments,
and not described herein.
[0148] As stated above, the map information display device
according to the present embodiment has the same characteristics as
those according to the second and fifth embodiments. That is, the
map information display device can gradually change the positional
information, and can display the map information based on the road
width information provided by the user. Therefore, even if the map
information is displayed with the road width being switched based
on the selection by the user, the objects are displayed so as not
to overlap with any roads, and a realistic screen can be presented
to the user.
[0149] (Seventh Embodiment)
[0150] FIG. 25 is a block diagram showing the structure of a map
information display device 7 according to a seventh embodiment of
the present invention. This map information display device 7
automatically converts map information for zero-width display into
the one for width display and displays the converted map
information, as in the fifth embodiment, and is used as being
incorporated into a vehicle navigation device, for example. The map
information display device 7 is constructed by adding the command
input unit 14 and the map information display unit 15 to the map
information changing device 3 according to the third embodiment.
Therefore, the map information display device 7 has the
characteristics of those according to the third and fifth
embodiments. The details on the map information display device 7
are thus evident from the above description of these embodiments,
and not described herein.
[0151] As stated above, the map information display device
according to the present embodiment has the same characteristics as
those according to the third and fifth embodiments. That is, the
map information display device can change the positional
information in one process in consideration of overlaps with a
plurality of roads, and can display the map information based on
the road width information provided by the user. Therefore, even if
the map information is displayed with the road width being switched
based on the selection by the user, the objects are displayed so as
not to overlap with roads, and a realistic screen can be presented
to the user.
[0152] (Eighth Embodiment)
[0153] FIG. 26 is a block diagram showing the structure of a map
information display device 8 according to an eighth embodiment of
the present invention. This map information display device 8
automatically converts map information for zero-width display into
the one for width display and displays the converted map
information, as in the fifth embodiment, and is used as being
incorporated into a vehicle navigation device, for example. The map
information display device 8 is constructed by adding the command
input unit 14 and the map information display unit 15 to the map
information changing device 4 according to the fourth embodiment.
Therefore, the map information display device 8 has the same
characteristics as those according to the second, third, and fifth
embodiments. The details on the map information display device 8
are thus evident from the above description of these embodiments,
and not described herein.
[0154] As stated above, the map information display device
according to the present embodiment has the same characteristics as
those according to the second, third, and fifth embodiments. That
is, the map information display device can gradually change the
positional information; can change the positional information in
one process in consideration of overlaps with a plurality of roads;
and can display the map information based on the road width
information provided by the user. Therefore, even if the map
information is displayed with the road width being switched based
on the selection by the user, the objects are displayed so as not
to overlap with any roads, and a realistic screen can be presented
to the user.
[0155] In the first, second, fifth, and sixth embodiments, the
position of the landmark and each vertex of the area are moved in a
direction perpendicular to the road. Alternatively, they may be
moved in a direction approximately perpendicular to the road. This
can also achieve the same effects as those described in the above
embodiments.
[0156] Furthermore, in the second or fourth, and sixth or eighth
embodiments, the object can be changed in position without
limitation so as not to overlap with a plurality of roads.
Alternatively, the changed positional information may be compared
with the original one, and if a difference therebetween is more
than a predetermined value (50 meters, for example) , the original
one is used. Such limitation can prevent erroneous changes in the
positional information.
[0157] In either of the above first through eighth embodiments, the
overlapping landmark and area are changed in position.
Alternatively, the overlapping road may be changed in position. If
the map information for zero-width display is a detailed city map
generated based on an aerial photograph, for example, the landmarks
and areas are first defined in position by using their shapes on
the photograph, and their positional information are used as a
reference in the map information. With reference thereto, the
positional information of the road may be changed. To change the
position of the road, the road to a position perpendicular to its
original position or only one endpoint of a segment composing the
road may be moved to a position perpendicular to the road. These
methods can also achieve the same effects as those described in the
above embodiments.
[0158] 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.
* * * * *