U.S. patent application number 09/087703 was filed with the patent office on 2001-08-09 for digital map display zooming method, digital map display zooming device, and storage medium for storing digital map display zooming program.
Invention is credited to MINAMI, MASAFUMI, NARIOKA, HIROTO, WATANABE, RYUICHI.
Application Number | 20010012017 09/087703 |
Document ID | / |
Family ID | 15358308 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010012017 |
Kind Code |
A1 |
WATANABE, RYUICHI ; et
al. |
August 9, 2001 |
DIGITAL MAP DISPLAY ZOOMING METHOD, DIGITAL MAP DISPLAY ZOOMING
DEVICE, AND STORAGE MEDIUM FOR STORING DIGITAL MAP DISPLAY ZOOMING
PROGRAM
Abstract
A digital map display zooming method for continuously enlarging
and reducing a displayed portion of a digital map as map
information in digital form within a display screen is provided
which comprises the steps of displaying the displayed portion of
the digital map at the display screen, displaying a scroll part
within the display screen for shifting the displayed portion,
making the scroll part function as a scale setting part for
carrying out enlarging and reducing operations of the displayed
portion of the digital map within the display screen, and carrying
out enlarging and reducing operations of the displayed portion of
the digital map within the display screen by shifting a shifting
operation part of the scale setting part.
Inventors: |
WATANABE, RYUICHI;
(KANAGAWA, JP) ; MINAMI, MASAFUMI; (TOKYO, JP)
; NARIOKA, HIROTO; (KANAGAWA, JP) |
Correspondence
Address: |
Oblon Spivak McClelland Maier & Neustadt PC
Fourth Floor 1755 Jefferson Davis Highway
Arlington
VA
22202
US
|
Family ID: |
15358308 |
Appl. No.: |
09/087703 |
Filed: |
June 1, 1998 |
Current U.S.
Class: |
345/619 |
Current CPC
Class: |
G09B 29/106 20130101;
G06F 3/0485 20130101; Y10S 715/973 20130101; G01C 21/3673 20130101;
G06F 2203/04806 20130101; G01C 21/367 20130101; G06F 3/03543
20130101; Y10S 715/974 20130101; G06F 3/0481 20130101; G06F 3/04855
20130101 |
Class at
Publication: |
345/619 |
International
Class: |
G09G 005/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 1997 |
JP |
P09-144275 |
Claims
What is claimed is:
1. A digital map display zooming method for enlarging and reducing
a displayed portion of a digital map as map information in digital
form within a display screen, said method comprising the steps of:
displaying said displayed portion of said digital map at said
display screen; displaying a scroll part within said display screen
for shifting said displayed portion; making said scroll part
function as a scale setting part for carrying out enlarging and
reducing operations of said displayed portion of said digital map
within said display screen; and carrying out enlarging and reducing
operations of said displayed portion of said digital map within
said display screen by shifting a shifting operation part of said
scale setting part.
2. The digital map display zooming method of claim 1, wherein said
shifting operation part of said scale setting part is displayed at
a side end of said display screen, and said displayed portion of
said digital map is continuously reduced when said shifting
operation part is shifted in an upward direction of the display
screen and said displayed portion of said digital map is
continuously enlarged when said shifting operation part is shifted
in a downward direction of the display screen.
3. A digital map display zooming device for enlarging and reducing
a displayed portion of a digital map as map information in digital
form within a display screen, said device by comprising: display
means having a display screen for displaying said displayed portion
of said digital map; a scale setting part provided to be displayed
at said display screen of said display means, said scale setting
part comprising a scroll part having a shifting operation part and
being displayed at said display screen with a function thereof
being changed for shifting said displayed portion, and carrying out
enlarging and reducing operations of said displayed portion of said
digital map within said display screen by operating said shifting
operation part; pointing means for operating said shifting
operation part of said scale setting part; and arithmetic
processing means for carrying out processing for enlarging and
reducing operations of said displayed portion of said digital map
within said display screen by shifting said shifting operation part
of said scale setting part with said pointing means being
operated.
4. The digital map display zooming device of claim 3, wherein said
shifting operation part is provided to be displayed at a side end
of said display screen, and said arithmetic processing means
carries out an arithmetic processing for continuously reducing said
displayed portion of said digital map when said shifting operation
part of said scale setting part is shifted in an upward direction
of said display screen and continuously enlarging said displayed
portion of said digital map when said shifting operation part of
said scale setting part is shifted in a downward direction of said
display screen.
5. The digital map display zooming device of claim 3, wherein said
pointing means is provided with a rotational operation part which
is operated to rotate so as to shift said shifting operation part
of said scale setting part, and said displayed portion of said
digital map is continuously reduced when said shifting operation
part is shifted in an upward direction of said display screen by
rotating said rotational operation part, and continuously enlarged
when said shifting operation part is shifted in a downward
direction of said display screen.
6. The digital map display zooming device of claim 4, wherein a
plurality of changeover marks showing changeover positions for data
of scales for said displayed portion of said digital map are
arranged at said scale setting part in a direction of operating
said shifting operation part at said scale setting part.
7. In a storage medium for storing a digital map display zooming
program for enlarging and reducing a displayed portion of a digital
map as map information in digital form within a display screen, the
improvement wherein said program comprises the steps of displaying
said displayed portion of said digital map at said display screen,
displaying a scroll part within said display screen for shifting
said displayed portion, making said scroll part function as a scale
setting part for carrying out enlarging and reducing operations of
said displayed portion of said digital map within said display
screen by operating said pointing means, and carrying out enlarging
and reducing operations of said displayed portion of said digital
map within said display screen by shifting a shifting operation
part of said scale setting part.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a digital map display
zooming method, a digital map display zooming device and a storage
medium for storing a digital map display zooming program, which are
for enlarging and reducing a displayed portion of a digital map as
map information in digital form within a display screen.
[0002] Digital maps as map information in digital form are maps put
into electronic form so as to be handled on the display screen of a
computer such as a portable computer etc. This kind of digital map
is referred to as an electronic map or map software, where maps can
be displayed on a display screen.
[0003] With this kind of digital map, a map is displayed on, for
example, the display screen of a portable computer so that an
operation such that a target is set on the map can be carried out,
with these digital maps being applied to car navigation systems
etc. in recent years.
[0004] Incidentally, related art operation for enlarging or
reducing the displayed portion of the digital map within the
display screen is carried out by a user operating prescribed
buttons.
[0005] However, with this kind of operation for enlarging or
reducing the displayed portion of the digital map, the displayed
portion of the digital map can only be enlarged or reduced in an
intermittent manner on certain scales of, for example, about four
steps. The displayed portion of the digital map therefore cannot be
displayed at a scale on which the user wishes to set.
[0006] It is therefore an object of the present invention to solve
the aforementioned problem to provide a digital map display zooming
method, a digital map display zooming device and a storage medium
for storing a digital map display zooming program which are capable
of easily displaying the displayed portion at an arbitrary rate of
enlargement by a user continuously enlarging or reducing the
displayed portion of the digital map while watching the display
screen.
SUMMARY OF THE INVENTION
[0007] The above object can be achieved in the present invention by
a digital map display zooming method for enlarging and reducing a
displayed portion of a digital map as map information in digital
form within a display screen, the method comprising the steps of
displaying the displayed portion of the digital map at the display
screen, displaying a scroll part within the display screen for
shifting the displayed portion, making the scroll part function as
a scale setting part for carrying out enlarging and reducing
operations of the displayed portion of the digital map within the
display screen, and carrying out enlarging and reducing operations
of the displayed portion of the digital map within the display
screen by shifting a shifting operation part of the scale setting
part.
[0008] In the present invention, the scroll part displayed within
the display screen for shifting the displayed portion functions as
a scale setting part for carrying out enlarging and reducing
operations of the displayed portion of the digital map. The user
can then carry out enlarging and reducing operations of the
displayed portion of the digital map within the display screen by
shifting the shifting operation part of the scale setting part.
[0009] In this way, the user can freely carry out enlarging and
reducing operations of the size of the displayed portion displayed
at the display screen with ease by only shifting the shifting
operation part of the scale setting part within the display screen
while watching the shifting operation part of the scale setting
part of the display screen.
[0010] In the present invention, if the user preferably carries out
an operation while looking at the side end of the display screen so
that the displayed portion of the digital map is continuously
reduced when shifting the shifting operation part of the scale
setting part in an upward direction of the display screen, and on
the contrary, the displayed portion of the digital map is
continuously enlarged when shifting the shifting operation part of
the scale setting part in a downward direction of the display
screen, there will be no mistakes in the zooming operations because
the displayed portion of the digital map will be enlarged and
reduced in conformity with the sense of up and down of the
user.
[0011] The above object can also be achieved in the present
invention by a digital map display zooming device for enlarging and
reducing a displayed portion of a digital map as map information in
digital form within a display screen, the device comprising a
display section having a display screen for displaying the
displayed portion of the digital map, a scale setting part provided
to be displayed at the display screen of the display section, the
scale setting part comprising a scroll part having a shifting
operation part and being displayed at the display screen with a
function thereof being changed for shifting the displayed portion,
and carrying out enlarging and reducing operations of the displayed
portion of the digital map within the display screen by operating
the shifting operation part, a pointing device for operating the
shifting operation part of the scale setting part, and an
arithmetic processor for carrying out processing for enlarging and
reducing operations of the displayed portion of the digital map
within the display screen by shifting the shifting operation part
of the scale setting part with the pointing device being
operated.
[0012] In the present invention the displayed portion of the
digital map is displayed at the display screen of the display
section. The scale setting part is displayed at the display screen.
This scale setting part is a scroll part displayed at the display
screen with a function thereof being changed for shifting the
displayed portion. The operation of zooming the displayed portion
can then be carried out by operating the shifting operation
part.
[0013] The pointing device is for the user to operate the shifting
operation part of the scale setting part.
[0014] The arithmetic processor carries out processing for carrying
out enlarging and reducing operations of the displayed portion of
the digital map within the display screen by shifting the shifting
operation part of the scale setting part by operations of the
pointing means.
[0015] As a result, the user can freely carry out enlarging or
reducing operation with ease for the size of the shifting displayed
portion displayed at the display screen only by shifting the
shifting operation part of the scale setting part within the
display screen while watching the shifting operation part.
[0016] The aforementioned object can also be achieved in the
present invention by a storage medium for storing a digital map
display zooming program for enlarging and reducing a displayed
portion of a digital map as map information in digital form within
a display screen, wherein the program comprises the steps of
displaying the displayed portion of the digital map is displayed at
the display screen, displaying a scroll part within the display
screen for shifting the displayed portion, making the scroll part
function as a scale setting part for carrying out enlarging and
reducing operations of the displayed portion of the digital map
within the display screen by operating the pointing means, and
carrying out enlarging and reducing operations of the displayed
portion of the digital map within the display screen by shifting a
shifting operation part of the scale setting part.
[0017] In the present invention, the user can freely carry out
enlarging or reducing operation with ease for the size of the
displayed portion displayed at the display screen only by shifting
the shifting operation part of the scale setting part within the
display screen while watching the shifting operation part.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a perspective view showing a portable
notebook-type personal computer as an embodiment of a digital map
zooming device of the present invention;
[0019] FIG. 2 is a block diagram showing a system for the digital
map zooming device of FIG. 1;
[0020] FIG. 3 is a view showing an example of a displayed portion
of a digital map displayed on the display screen of the digital map
display zooming device of FIG. 1;
[0021] FIG. 4 is a view showing an example of an enlarged display
of the displayed portion of the digital map of FIG. 3;
[0022] FIG. 5 is a view showing a scale bar, a scale bar knob and a
mouse;
[0023] FIG. 6 is a perspective view showing another example of a
mouse as a pointing means used in the present invention;
[0024] FIG. 7 is a side view of the mouse of FIG. 6;
[0025] FIG. 8 is a view showing a flowchart for processing as a
scale bar knob;
[0026] FIG. 9 is a view showing a flowchart of a scale bar
display;
[0027] FIG. 10 is a view showing a concept of continuous
enlargement and reduction as continuous zooming; and
[0028] FIG. 11 is a view showing a flowchart of continuous
zooming.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] In the following a preferred embodiment of the present
invention will be described in detail on the basis of the attached
drawings.
[0030] The embodiment described in the following is a specific
preferred example of the present invention and is thereby subject
to various technical limitations. However, the scope of the present
invention is by no means limited to these forms in the following
explanation unless otherwise described to limit the present
invention.
[0031] FIG. 1 is a perspective view showing a preferred embodiment
of a digital map zooming device 100 of the present invention. A
system configuration for this digital map zooming device 100 is
shown in FIG. 2.
[0032] The digital map zooming device 100 of FIG. 1 is a so-called
portable notebook type personal computer which has a main body 2,
display means 3, a mouse 6, a touch pad 12 and touch pads 31 and
32. The display means 3 has a display screen 4 to which, for
example, a Liquid Crystal Display (LCD) can be adopted. The display
means 3 is attached to the main body 2 in such a manner as to be
capable of being opened and closed.
[0033] The main body 2 has the aforementioned mouse 6, touch pads
12, 31 and 32 and a keyboard 11 as pointing means, and a power
supply lamp 15 etc.
[0034] FIG. 2 is a block diagram showing the system configuration
within the main body 2 and the display means 3.
[0035] The main body 2 has a floppy disc drive (FDD) 86, a CDROM
(read-only memory utilizing a compact disc) drive 87, a detector
circuit 84 for a keyboard 11, a CPU (central processing unit) 81, a
ROM (read-only memory) 82, a RAM (random access memory) 83 and a
controller 51.
[0036] Touch pads 12, 31, 32 and a mouse 6 are connected to a
controller 51. The controller 51, the ROM 82, the RAM 83, the
detector circuit 84, the hard disc drive 85, the floppy disc drive
86 and the CD-ROM drive 87 are connected to a CPU 81 via a bus
BA.
[0037] The mouse 6 of FIG. 1 has a mouse body 6a, a left button 6b
and a right button 6c. The touch pad 31 with a function similar to
that of the left button and the touch pad 32 with a function
similar to that of the right button are provided below the touch
pad 12.
[0038] The CPU 81 of FIG. 2 executes various processings in
accordance with a program stored at the ROM 82. The data and
programs etc. necessary for the CPU 81 to execute various processes
are stored in an appropriate manner at the RAM 83. The detector
circuit 84 detects operation of the key 11 and outputs a detection
signal to the CPU 81.
[0039] The hard disc drive (HDD) 85 stores programs processed by
the CPU 81 and data etc. in an appropriate manner. The floppy disc
drive (FD) 86 records and plays back data to and from a floppy disc
89 installed therein.
[0040] The controller 51 detects operations of the touch pad 12,
the touch pads 31 and 32 and the mouse 6 and outputs a detection
signal to the CPU 81.
[0041] When the user shifts a pointer 5 using the touch pads 12, 31
and 32, the user touches (presses) a prescribed position on the
touch pad 12 with their finger, and shifts this touching position
in the direction that the pointer 5 is to be shifted. The
controller 51 detects this operation, i.e. when the user applies a
pressure to the touch pad 12 with their finger, the electrostatic
capacity of the position being pressed changes. For example, when a
certain position on the touch pad 12 is pressed by a finger, the
electrostatic capacitance between a horizontal electrode and a
vertical electrode changes largely compared to the electrostatic
capacitance between other electrodes.
[0042] When a key of the keyboard 11 is operated, the detector
circuit 84 outputs a detection signal corresponding to this
operation to the CPU 81. The CPU 81 then generates, for example,
prescribed character data in accordance with this inputted
detection signal with this character data being outputted to the
display screen 4 and displayed. In a similar manner, the CPU 81
reads out graphics data for the pointer 5 stored in the ROM 82 and
outputs this data to the display screen 4 for displaying. In this
way, the pointer 5 is displayed as shown, for example, in FIG.
1.
[0043] The controller 51, CPU 81, ROM 82, RAM 83 and detector
circuit 84 in FIG. 2 comprise arithmetic processing means 120. The
arithmetic processing means 120 is a portion having a function for
carrying out enlarging and reducing operations of the displayed
portion of a digital map within the display screen as a result of
shifting a shifting operation part of a scale setting part to be
described later by operating the mouse 6 as the pointing means.
[0044] FIG. 3 shows an image 130 included in a digital map display
zooming program displayed on the display screen 4 of the display
means 3 of FIG. 1 and FIG. 2. Although this image 130 is simply an
example, a title bar 131, a menu bar 132, a tool bar 133, a
(information display) list box 134, a guidance area 135, a map
display region 136, a map window title bar 138, a scale display
139, a latitude/longitude display 140, a (zoom in) button 141, a
(zoom out) button 142, a scale bar 143, a scale bar knob (also
referred to as "slider") 144, a maximizing button 145, a minimizing
button 146 and an X button (close button) 147 etc. are displayed
within this image 130. A separate window 130b is displayed within a
window 130a of the image 130.
[0045] An example of a displayed portion 150 of the digital map is
displayed within this window 130b of FIG. 3 and FIG. 4 that is an
enlarged display of the displayed portion 150 of FIG. 3. The menu
bar 132 is positioned below the title bar 131 and is lined up with
function names, and when clicking is performed with the pointer 5
being positioned at this menu bar 132, a more detailed display is
given. A window is a displayed portion surrounded by a window-like
frame opened on the computer screen. The term "clicking" means an
operation of quickly pressing and releasing the mouse button.
[0046] FIG. 5 shows a scale bar 143 as the scale setting part shown
in FIG. 3 and FIG. 4 and a scale bar knob 144 as a shifting
operation part of the scale setting part together with the mouse 6.
The scale bar knob 144 and the scale bar 143 can also be selected
to function as a scroll bar for scrolling pictures.
[0047] The scale bar knob 144 is pointed out by an arrow-type
pointer 5 by pressing the left button 6b of the mouse 6 as the
pointing means of FIG. 1 and this scale bar knob 144 can be shifted
in a reducing direction DR1 (upwards on the display screen) as a
result of the user moving the mouse 6 in a direction of, for
example, E1 on a desk DK. The scale bar knob 144 can then be
shifted in an enlarging direction DR2 (downwards on the display
screen 4) as a result of the user moving the mouse 6 in a direction
E2.
[0048] When the scale bar knob 144 is shifted in the reducing
direction DR1, the displayed portion of the digital map 150
displayed at the display screen 4 shown in FIG. 3 and FIG. 4 can be
continuously (in an analog manner) reduced in accordance with the
amount of shift. For example, the displayed portion of the digital
map 150 is continuously reduced as the scale bar knob 144 goes
along marks M1, M2, M3, M4 and M5 of the scale bar 143. This
presents an image seen from a manned spacecraft rising from earth
into space.
[0049] Contrary to this, when the scale bar knob 144 is shifted in
the enlarging direction DR2, the displayed portion of the digital
map 150 can be continuously (in an analog manner) enlarged. This
gives an image seen from a spacecraft descending from space to the
surface of the earth.
[0050] When clicking is made with an arbitrary position of the
scale bar 143 being pointed out by the pointer 5, the displayed
portion 150 for the map is displayed on the scale value for this
position.
[0051] In the embodiment in FIG. 5, the marks M1, M2, M3, M4 and M5
of the scale bar 143 show changeover positions i.e. dividing
positions of data of the digital map which are also referred to as
map layers. The enlargement rate is kept to be changed markedly at
each of the marks M1 to M5 as the scale bar knob 144 is shifted
along the marks. The enlargement rate of the displayed portion of
the digital map 150 can be then made to be changed, for example, in
accordance with the enlargement rate indicated by characters at the
marks M1 to M5.
[0052] FIG. 6 shows another example of a mouse which is different
from the mouse 6 of FIG. 1 and FIG. 5. This mouse 106 is in the
tradename "Intellimouse" of the Microsoft Co., Ltd. with a left
button 106b, right button 106c and rotary wheel 106d provided at a
main body 106a.
[0053] For example, by the user rotating the rotary wheel 106d in
the direction R1 while holding down the left button 106d of the
mouse 106, the scale bar knob 144 of FIG. 5 can be shifted in the
reducing direction DR1 by the amount of rotation of the rotary
wheel 106d. Moreover, by rotating the rotary wheel 106d in the
direction R2, the scale bar knob 144 can then be shifted in the
enlarging direction DR2 in accordance with the amount of
rotation.
[0054] A mouse is a device that is slid on a desk to point specific
portions of the screen.
[0055] The programs for the digital map display zooming method in
the embodiment of the present invention are shown in FIG. 8, FIG. 9
and FIG. 11. The programs are operated on the operation system such
as Windows' 95 of the Microsoft Co., Ltd. in U.S. The operating
system (OS) is a software with functions such as "execution of
applications" and "file management" that are the basis for using a
computer.
[0056] The program for the display zooming method is stored on, for
example, the CD-ROM 88 of FIG. 2. The digital map display zooming
program of this CD-ROM 88 can then be put onto the hard disc drive
85 by inserting the CD-ROM 88 into the CD-ROM drive 87.
[0057] Alternatively, such a digital map display zooming program
can be stored on the floppy disc 89 instead of the CD-ROM 88. When
the floppy disc 89 is inserted into the floppy disc drive 86, the
digital map display zooming program within this floppy disc 89 is
then put onto the hard disc 85.
[0058] Alternatively, the digital map display zooming program can
be put onto the hard disc drive 85 from outside via a network such
as the internet.
[0059] FIG. 8 shows an example of the processing for enlarging
operation of the displayed portion 150 at the display screen 4 when
the scale bar knob (also referred to as a slider) 144 shown in FIG.
5 is shifted by the user. In step SP50, an event occurs when the
user shifts the scale bar knob 144. In step SP51, the current
position of the knob i.e. the length for the current position of
the scale bar knob 144 (LENGTH.sub.KNOB) at the scale bar 143 is
obtained.
[0060] In step SP52, a map layer A with a length of LENGTH A is
obtained which is the minimum of the lengths of LENGTH N for the
map layers N at the displayed portion of the digital map 150 that
satisfy the condition LENGTH N.gtoreq.LENGTH.sub.KNOB. In step
SP53, the enlargement rate is then obtained and in step SP54 the
map layer A of the displayed portion is drawn at the obtained
enlargement rate. The map layer is referred to as map data of the
digital map.
[0061] FIG. 9 shows an example of the processing for displaying
each of scales for map data (layers) of a plurality of scales
stored on a map disc (storage medium) such as the CD-ROM 89 on the
scale bar 143.
[0062] When a CREATE/RESIZE event for a map window is received in
step SP100 of FIG. 10, the length of the scale bar 143 at the
display screen (LENGTH.sub.S) is obtained in step SP101. In step
SP102, scale information (unit: Meter/Dot) for all of the map
layers on the map disc is read out.
[0063] In step SP103, the scale of the map layer for the broadest
region of the presented ones is taken to be Smax and the scale Smin
of the map layer for the narrowest region is determined to be
Smin=0.5 Meters/Dot.
[0064] In SP104 and SP105, conversion coefficients K are calculated
and the positions N of various map layers L are calculated. In step
SP106, linear markers M1 to M5 as shown in FIG. 5 are displayed at
prescribed positions of the scale bar 143 for various layers N.
[0065] FIG. 10 conceptually shows a currently selected digital map
layer of scale Sn used in a continuous zooming, namely continuous
enlargement and reduction, of the displayed portion, a digital map
layer of scale S(n-1) for one-step enlargement and a digital map
layer of scale S(n+1) for one-step reduction in three
dimensions.
[0066] The above digital map layers are the data for the program
shown by the flowchart of FIG. 11.
[0067] Next, an example of carrying out a zooming operation of the
displayed portion 150 of the digital map in FIG. 3 in accordance
with the digital map zooming display program will be described with
reference to FIG. 11.
[0068] A CD-ROM 88 is inserted into, for example, the CD-ROM drive
87 of FIG. 2. Alternatively, a floppy disc 89 is inserted into the
floppy disc drive 86.
[0069] As a result, a preferred embodiment of the digital map
display zooming program of the present invention, which is stored
on the CD-ROM 88 or the floppy disc drive 89, is put onto the hard
disc drive 2 of the hard disc via the bus BA.
[0070] When these preparations are finished, the window 130b is
displayed at the display screen 4 of the display means 3 of FIG. 3.
This window 130b is a window of the digital map.
[0071] FIG. 11 is a flowchart showing continuous zooming at the
displayed portion 150 of the digital map. At the time of starting
continuous zooming using the scale bar knob 144 of FIG. 5, the
scale for the map layer, i.e. data, within the storage disc such as
the CD-ROM is taken to be Sn (unit: meter/dot) and this data is
supposed to be in being displayed at the display screen 4 of FIG. 1
on a scale Sc.
[0072] Further, the unit (meter/dot) for the scale S expresses the
actual distance on the map corresponding to one display pixel.
[0073] In FIG. 11, fzoom-in (Sc) represents the enlargement rate
(for example, 80%) and fzoom-out (Sc) represents the reduction rate
(for example, 125%). The enlargement rate and the reduction rate
both relate to two dimensions (line segments).
[0074] Currently, the enlargement rate and the reduction rate are
set so that they are in a relation as fzoom-in
(1/fzoom-out)=constant (for example, 0.8), but this value can be
freely changed if so desired. For example, an operation is also
possible which increases the enlargement rate depending on
acceleration as the surface of the earth 2 becomes closer.
[0075] Upon starting in step SP1 of FIG. 11, it is assumed that the
displayed portion of the digital map has already been in the zoom
mode at this start time.
[0076] In step SP2 a determination is made as to whether or not the
scale bar knob 144 of FIG. 5 has been shifted in the reducing
direction DR1 (upwards) or the enlarging direction DR2
(downwards).
[0077] When the scale bar knob 144 is shifted downwards, the
process goes to enlargement processing of step SP3, and when the
scale bar knob 144 is shifted upwards, the process goes to the
reduction processing of step SP10.
[0078] In step SP3, a calculation is carried out for the next scale
"New Scale" that is to be set by the user with the scale bar knob
144. This new scale is expressed as "Snew". In step SP4, a scale
S(n-1) for a map layer (data) is obtained which is for one-step
enlargement of the digital map currently being displayed.
[0079] In step SP5, the new scale Snew and the scale S(n-1) in step
SP4 are compared. When the new scale Snew is greater, the process
goes to step SP6, and when this is not the case, the process goes
to step SP7.
[0080] In step SP6, the map layer (data) currently being displayed
is enlarged and displayed. While, in step SP7, the map layer (data)
for one-step enlargement is enlarged.
[0081] By doing this, the displayed portion can be displayed with
respect to the object data at the display screen 4 in FIG. 5.
[0082] Compared with this, in step SP10, a calculation is carried
out for the next scale "New Scale" that is to be set by the user
with the scale bar knob 144. When this new scale "Snew" is larger
than the scale S(n+1) of the map layer on the disc, the process
goes to step SP12 and when this is not the case the process goes to
step SP14.
[0083] In step SP12, a scale S(n+1) for the map layer is obtained
which is for one-step reduction of the map currently being
displayed. Then, in step SP13, the map layer (data) is reduced
which is for one-step reduction. Compared with this, the map layer
(data) currently being displayed is then reduced in step SP14.
[0084] The object data can thus be displayed in being enlarged or
reduced continuously and smoothly in response to the scale bar knob
144 being shifted by the user.
[0085] The present invention is by no means limited to the above
embodiment.
[0086] In the above embodiment an example is shown where the
digital map display zooming program of the present invention is
stored on the CD-ROM 88 or the floppy disc drive 89 shown in FIG.
1. However, the present invention is by no means limited in this
respect, and this can also be stored so as to be installed
beforehand on a hard disc of the hard disc drive 85. Alternatively,
this digital map display zooming program can be stored on, for
example, the hard disc 85 of the hard disc drive via a network such
as an external internet. Other types of disc such as a high-density
recording disc (DVD) can also be used as the recording medium.
[0087] Further, the digital map display zooming device of FIG. 1 is
a notebook type personal computer, but the present invention is by
no means limited in this respect, and can also be applied to
desktop personal computers, navigation systems mounted on moving
vehicles such as cars and to portable navigation systems.
[0088] As described above, according to the present invention, the
displayed portion can easily be displayed at an arbitrary
enlargement rate by the user continuously enlarging or reducing the
displayed portion of the digital map while watching the display
screen.
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