Location floor number display device in navigation apparatus

BACKGROUND OF THE INVENTION

1. Field of the Invention

0001The present invention relates to a location floor number display method in a navigation apparatus and, more particularly, to a location floor number display method which visually displays the floor number of a floor, in a building, on which a target object is located and displays detailed information of the target object.

2. Description of the Related Art

0002A navigation apparatus which performs traveling guide of a vehicle to make a driver to easily reach a target place detects the position of the vehicle, reads map data of the outskirts of the vehicle position from a CD-ROM, draws a map image on a display screen, and draws a vehicle position mark (vehicle position mark) at a predetermined position on the map image to overlap them. In accordance with a change in present position by moving of the vehicle, the vehicle position mark of the screen is moved, or the vehicle position mark is fixed at a predetermined position such as the center of the screen to scroll the map, so that the map information of the outskirts of the vehicle position can be always understood at a sight.

0003The navigation apparatus has a route guide function which searches a guide route from a start place to a target place, displays the guide route on a map, and performs intersection guide (display of an enlarged view of an intersection and a display of a proceeding direction).

0004A recent navigation apparatus is designed such that various pinpoint searching operations can be performed by using Yellow Page data or detailed town map information. The detailed town map information is detailed map information including the positions of planar shapes of buildings, roads, and the like such that, with respect to a town, the shapes of buildings, the widths of roads, the positions of signals, the directions of one-way roads, blind alleys, and the like can be realistically recognized.

0005As Yellow Page data, ① a telephone number database in which a telephone number is input to search the institution (various types of stores, sales offices, banks, or the like) of the telephone number and to display the map of the outskirts of the institution; ② an institution database which covers the names, jobs, positions (longitude/latitude), and the like of institutions (stores, sales offices, banks, and the like) in units of institutions; ③ a building database; and the like are known. The building database covers detailed information (names, telephone numbers, addresses) of longitude/latitude positions, names, building users (companies, offices, and the like) in units of buildings.

0006As pinpoint searching, for example, Yellow Page telephone number searching, pinpoint outskirts information searching, Japanese syllabary searching, and the like are used.

0007The Yellow Page telephone number searching is a method of inputting the telephone number of a target institution to search the map of the outskirts of the institution and to display the map. A user operates the menu of a remote controller to request telephone number searching. When the user inputs a telephone number of a desired institution (e.g., a department store), a navigation control device calculates the department store name of the input telephone number with reference a telephone-number-classified database, calculates position data of the department store with reference to the institution database, and reads the map of the outskirts of the department store on the basis of the position data.

0008The pinpoint outskirts information searching is a method of searching a target institution such as a drug store or a coffee shop within a radius of 1 km of a vehicle position or an arbitrary position from 52-genre job classification to display the map of the outskirts of the target institution is displayed. When a user operates the menu of a remote controller to request a map displayed by the outskirts information searching, the navigation control device displays a job-classified list. When the user selects a predetermined job name (e.g., department store), the navigation control device searches department stores within a radius of 1 km of the vehicle position with reference to the institution database to display a department store name list. When the user selects a desired department store name, the navigation control device displays the position of the department store selected with reference to the institution database on the map.

0009The Japanese syllabary searching is a method of searching the map of the outskirts of an institution by inputting the institution name with Japanese syllables to display the map. When a user operates the manu of a remote controller to request map searching by inputting Japanese syllables, and the name of a desired institution (e.g., department store) is input with Japanese syllables, the navigation control device searches only a part of the name by partial coincidence searching to calculate the department store name with reference to the institution database. The navigation control device calculates the position data of the indicated department store with reference to the institution database, and read the map of the outskirts of the department store on the basis of the position data to display the map on the display screen.

0010On the basis of the detailed town map information, a detailed town map is displayed as shown in FIG. 14A, a target building is indicated by a cursor CSR, and "information" is selected from a setup menu. In this case, user names (company names or tenant names) of the building are listed in the order of Japanese syllabary as shown in FIG. 14B with reference to the building database, and a predetermined user is selected from the list. At this time, as shown in FIG. 14C, the name, address, telephone number of the user (company/tenant) are displayed (detailed information display). According to this detailed information display function, a location can be easily checked even if the target place is in a building. Even in a complicated street lined with buildings, the user does not lose his/her way. More specifically, the building of the target place can be recognized by the detailed information display function. For this reason, when the building is input as a target place, a guide route to the building is searched to be displayed, and the user can reach the target place even in a complicated street lined with buildings without losing his/her way.

0011As described above, according to a conventional detailed information display function, a route to a building in which a target institution is located can be searched to be displayed. However, the floor number of a floor, in the building, on which the target institution is located cannot be known.

SUMMARY OF THE INVENTION

0012Therefore, it is the first object of the present invention to display the floor number of a floor, in a building, on which a target institution is located to reliably guide a user to the target institution.

0013It is the second object of the present invention to three-dimensionally display a building so that the floor number of a floor, in a building, on which a target institution is located is visually simply displayed.

0014It is the third object of the present invention to three-dimensionally display an actual building, even if the number of floors in the building is large, without sticking out of a screen or three-dimensionally display a building, even if the number of floors in the building is small, with a proper height.

0015It is the fourth object of the present invention to display the number of floors in the basement of a building in which a target institution is located to make it possible to easily recognize a location position.

0016According to the present invention, the first and second objects can be achieved by a location floor number display method of a navigation apparatus comprising the steps of: (1) storing detailed map information including planar shapes of buildings and roads and storing building information including the number of floors of each building, a user name of a building, and the floor number of a floor on which a user is located; (2) displaying a detailed map on a display screen by using detailed map information; (3) when a building on the detailed map is indicated, calculating a user name list of the building from the building information to display the user name list on a part of the display screen, and displaying the detailed map displayed on the other part such that the detailed map is inclined by an image process (e.g., birds-eye process), and three-dimensionally displaying the indicated building with a height corresponding to the number of floors; (4) when a user is specified from the user list, calculating the floor number of a floor on which the user is located from the building information; and (5) displaying the floor number in the building three-dimensionally displayed such that the floor number can be identified, or displaying the floor number by letters.

0017According to the present invention, the first and second objects are achieved by a location floor number display method of a navigation apparatus comprising the steps of: (1) storing detailed map information including planar shapes of buildings and roads and storing building information including the number of floors of each building, a user name of a building, and the location floor number of a user; (2) displaying a detailed map including a building in which a target object is located by pinpoint searching on a display screen by using the detailed map information; (3) thereafter, displaying user information of a building user serving as the target object on a part of the display screen and displaying the detailed map on the other part such that the detailed map is inclined by an image process (e.g., birds-eye process), and three-dimensionally displaying the building with a height corresponding to the number of floors; (4) calculating the floor number of a floor on which the user is located from the building information; and (5) displaying the floor number in the building three-dimensionally displayed such that the floor number can be identified, or displaying the floor number by letters.

0018According to the present invention, the third object is achieved by a location floor number display method of a navigation apparatus comprising the steps of increasing compressibility as the number of floors of the building increases, and three-dimensionally displaying the building with a height obtained by multiplying the compressibility by the number of floors of the building.

0019According to the present invention, the fourth object is achieved by a location floor number display method of a navigation apparatus comprising the step of, when a user is located in a basement, displaying a location floor number in the basement by letters.

BRIEF DESCRIPTION OF THE DRAWINGS

0020<ul id="ul0001" list-style="none" compact="compact"><li>FIG. 1 is a view for explaining a three-dimensional building display of the present invention.</li><li>FIG. 2 is a view showing the arrangement of a navigation apparatus.</li><li>FIG. 3 is a view for explaining the arrangement of road data in map data.</li><li>FIG. 4 is a view for explaining detailed map graphic data.</li><li>FIG. 5 is a view for explaining a detailed town map.</li><li>FIG. 6 is a view for explaining building data.</li><li>FIG. 7 is a view for explaining a location floor number display process using detailed building information of the present invention.</li><li>FIG. 8 is a view for explaining a viewpoint position of a birds-eye process.</li><li>FIG. 9 is a view for explaining a building display.</li><li>FIG. 10 is a view for explaining another location floor number display process using detailed building information of the present invention.</li><li>FIG. 11 is a view for explaining a birds-eye process (part 1).</li><li>FIG. 12 is a view for explaining a birds-eye process (part 2).</li><li>FIG. 13 is a view for explaining a birds-eye view.</li><li>FIG. 14 is a view for explaining a conventional detailed information display.</li></ul>

DESCRIPTION OF THE PREFERRED EMBODIMENT

(a) Three-dimensional Building Display of the Present Invention

0021FIG. 1 is a view for explaining a three-dimensional building display of the present invention. In FIG. 1, reference symbol BL denotes a building in which a target object (building user) is located; FL, an L-shaped mark for visually displaying the floor number of a floor on which a building user serving as an object is located; MP, an outskirts map image subjected to a birds-eye process while a height is set to be zero; and FLC, letters indicating a location floor number.

0022When the detailed town map MP is displayed on a display screen by using detailed map information including the planar shapes of buildings and roads, and the building BL on the detailed map is indicated, the detailed map is inclined by an image process (birds-eye process) to be displayed, and the indicated building BL is three-dimensionally displayed with a height corresponding to the number of floors. When a target object institution (building user) is specified, the floor number of a floor on which the user is located is calculated from the building information, and the number of floors is displayed in the building BL with the L-shaped mark FL such that the number of floors can be identified, or the number of floors is displayed by the letters FLC.

(b) Navigation Apparatus

0023FIG. 2 is a view showing the arrangement of a navigation apparatus of the present invention. Referring to FIG. 2, reference numeral 11 denotes a map storage medium, e.g., a CD-ROM, for storing map information; 12, a CD-ROM controller for controlling reading of the map information from the CD-ROM; 13, a position measurement device, for measuring the present position of a vehicle, which is constituted by a vehicle speed sensor for detecting a moving distance, a gyro for detecting a moving azimuth, a GPS, a CPU for calculating a position, and the like. Reference numeral 14 denotes a map information memory for storing the map information read from the CD-ROM; 15, a Yellow Page data storage memory for storing Yellow Page data read from the CD-ROM; 16, a remote controller for performing a menu selecting operation, an enlarging/reducing operation, a manual map scroll operation, and the like; and 17, a remote control interface.

0024Reference numeral 18 denotes a processor (CPU) for controlling the navigation apparatus as a whole; 19, a ROM for storing various types of programs (guide route searching process, pinpoint searching process, location floor number display process, and the like); 20, a RAM for storing a process result; 21, a display controller for generating a map image; 22, a video RAM for storing the map image generated by the display controller; 23, a menu/detailed information generator for generating a menu image or detailed information in a pinpoint searching process; 24, a cursor image generator; 25, a vehicle position mark generator; 26, an image synthesizer; 27, a display device for displaying an image output from the image synthesizer; and 28, a bus.

(b) Recording Contents of CD-ROM

0025In addition to regular map information, Yellow Page data, detailed town map information, and the like are recorded on the CD-ROM 11.

(b-1) Regular Map Information

0026The regular map information is constituted by: (1) a road layer; (2) a background layer for displaying an object on a map; (3) a letter layer for displaying letters of city, town, and village names; (4) an IIS layer for storing IIS (Integrated Information Service) information. Of these layers, the road layer has road link data RLDT, node data NDDT, and intersection data CRDT as shown in FIG. 3.

0027The road link data RLDT is to give attribute information of a corresponding road, and is constituted by data such as the number of all nodes on a road link, numbers of nodes constituting the road, a road number (road name), and the type of the road (national road, highway, prefectural road, or other road).

0028The intersection data CRDT is a set of nodes (to be referred to as intersection constituting node), of the nodes connected to each intersection on a map, which are closest to the corresponding intersection. The node data NDDT is a list of all nodes constituting a road, and is constituted by position information (longitude/latitude) of each node, an intersection identification flag representing whether the node is an intersection, and a pointer or the like for indicating intersection data if the node is an intersection or indicating a road link to which the node belongs if the node is not an intersection.

(b-2) Detailed Town Map Information

0029Detailed town map information is divided into units each of which is divided to have a longitude width and a latitude width. The range of each unit on absolute longitude/latitude coordinates (X,Y), as shown in FIG. 4, is managed by absolute longitude/latitude coordinates (X_T1,Y_T1) and (X_T2,Y_T2) of diagonal ends E and F. The map graphic data of each unit defines a large number of planar shapes such as roads, buildings, and parks. As shown in FIGS. 4A and 4B, the map graphic data includes, in addition to 1 a line, a primitive type such as a polygon, a color, a line type, and an attribute representing the presence/absence of painted over, and 2 longitude/latitude coordinate strings (x₁,y₁), (x₂,y₂),..., (x_n,y_n) of element points G₁ to G_n 1 such as a bent point if a line is defined and a vertex if a polygon is defined. By using the detailed map information, the detailed town map of the outskirts of an indicated spot (vehicle position or target place) can be displayed at a scale of 25m/50m as shown in FIG. 5.

(b-3) Yellow Page Data

0030As Yellow Page data, 1 a telephone number database for searching the institution of a telephone number by inputting the telephone number to display the map of the outskirts of the institution; 2 an institution database which covers the names, jobs, longitude/latitude positions, and the like of institutions; 3 a building database; and the like are known. The building database is to provide the detailed information of buildings. As shown in FIG. 6, the building database has a hierarchical structure constituted by a building database BDB1 → a building user database BDB2 → a detailed user information database BDB3.

0031The building database BDS1 covers the longitude/latitude position, the name, and the number of floors of each building, the building user database BDB2 covers the user name (company/tenant name) of the building, and the detailed user information database BDB3 covers the detailed information of a user, i.e., a user name, a telephone number, an address, the location floor number of the user, and the like.

(c) Location Floor Number Display Method using Detailed Building Information

0032FIG. 7 is a view for explaining the sequence of a location floor number display method using detailed building information of the present invention.

0033A cursor is positioned in the outskirts of a target place by using the regular map, and a town map display is selected. With this operation, the display controller 21 generates the town map image of the outskirts of the target place by using the detailed town map information of the outskirts of the target place to display the town map on a display screen. The town map is scrolled by operating the remote controller 16 to display a target building. The building is selected by the cursor CSR to press a decision key. These operations are in step 101.

0034By pressing the decision key, the menu/information generator 23 generates a setup menu MN to display the setup menu MN on the map such that the setup menu MN overlaps the map. In this manner, when a predetermined item of the setup menu MN is selected, route searching is performed by using a spot (building) indicated by the cursor as a target place, the spot is registered as a passing point, spot registration is performed, or the detailed building information can be displayed. These operations are in step 102.

0035When "information" is selected from the setup menu by a remote control operation, or when a set period of time has elapsed without any operation, the menu/information generator 23 is started. The menu/information generator 23 calculates a user name list (object list) of a building indicated by the cursor CSR from the building database stored in the Yellow Page data memory 15, and displays a user name list LST of the building in the order of Japanese syllabary on the left half of the screen in place of the setup menu. These operations are in step 103.

0036The display controller 21 performs a birds-eye process (to be described later) to the town map displayed on the right half and displays the town map such that the map is gradually inclined. For example, as shown in FIG. 8, the map is sequentially rotated in a predetermined direction (A direction) while a distance H from a position above an indicated building BL to the building is kept constant and a viewpoint EY faces the ground, the birds-eye process is performed at viewpoint positions (x-mark positions) by using the planar shape data of the buildings and roads, and the town map is displayed on the basis of the shape data subjected to the birds-eye process. When the process is performed until a straight line connecting the viewpoint to the building and the ground make 45°, the town map is displayed such that the town map is gradually inclined.

0037Upon completion of the inclining operation, the display controller 21 calculates the number of floors of the building indicated by the cursor CSR from the building database, raises the building with a height corresponding to the number of floors, and three-dimensionally displays the building BL.

0038The display controller 21 calculates the floor number of a floor on which a user who is selected (displayed to be highlighted) from the user name list LST is located from the building database, displays the number of floors by an L-shaped mark FL in the three-dimensional building BL such that the number of floors can be identified, and, at the same time, the floor number (6F) is displayed by letters FLC. The floor number may be displayed by only one of the L-shaped mark or letters. These operations are in step 104.

0039The three-dimensional display of the building is performed by the following manner. A vertical compressibility α is increased as the number of floors Ft of the building increases, and the planar shape of the building is raised from the ground up to a height H (= Ft·α) obtained by multiplying the number of floors of the building by the compressibility. The width W of the L-shaped mark FL is a value (= H/Ft) obtained by dividing the height H by the number of floors, and a mark drawing position is a position having a height h (= F·Ft) where the floor number of the user is represented by F. The numbers of floors of buildings are classified into three sections, i.e., 1st to 10th floors, 11th to 30th floors, and 30th or more floors. The vertical compressibilities of the sections are represented by α₁, α₂, and α₃, respectively, and the compressibility of the section in which the number of floors is large is made high (α₁ &lt; α₂ &lt; α₃). In this manner, the building, even if the number of floors of an actual building is large, can be displayed without stacking out of the screen or the building, even if the number of floors is small, can be three-dimensionally displayed with a proper height.

0040FIG. 9 is a display example of a building in consideration of the above circumstances. When a user is located in a basement, as shown in FIG. 9D, only the building is three-dimensionally displayed without displaying the L-shaped mark, and the floor number in the basement on which the user is located is displayed like the "second basement".

0041A target building user name is selected (displayed to be highlighted) on the user name list LST by a remote control operation. In this manner, the floor number of a floor on which the new selected user is located is calculated from the building database, and the floor number is displayed in the three-dimensional building BL by the L-shaped mark FL such that the floor number can be identified. At the same time, the floor numbers (7F) is displayed by the letters FLC. These operations are in step 105.

0042When the decision key of the remote controller is operated in this state, the navigation apparatus calculates the detailed information (user name, telephone number, and address) DIF of the selected user from the building database to display the detailed information on the left side of the display screen in place of the user name list LST. In this manner, the floor number of a floor, in the building, on which a target institution is located can be checked, and the address and the telephone number can be obtained. These operations are in step 106.

0043When a building (spot indicated by cursor) is set as a target place, the CPU begins to search an optimum route from the vehicle position to the target place. These operations are in step 107.

(d) Another Location Floor Number Display Process using Detailed Building Information

0044The embodiment in FIG. 7 describes a case wherein a building is specified, and then a user name is specified. However, when pinpoint searching is performed by telephone number searching or Japanese syllabary searching, a town map including a building in which a target institution (building user) is located is displayed. In this case, the user has been specified, and a new user name need not be specified.

0045FIG. 10 is a view for explaining another location floor number display process using detailed building information according to the present invention in a case wherein a user has been specified as described above, and a new user name need not be specified.

0046Telephone number searching is selected by operating the menu of a remote controller to display a telephone number searching screen. Thereafter, the telephone number of a target institution is input. These operations are in step 201.

0047By inputting a telephone number, the CPU 18 calculates the institution name of the input telephone number with reference to a telephone-number-classified database stored in the Yellow Page data memory 15. The CPU 18 calculates the position data of the institution with reference to the institution database, and reads the detailed town map information of the outskirts of the institution into the map information memory 14 on the basis of the position data. The display controller 21 controls the display screen to display a town map having a target institution or a building in which the target institution is located at the center of the screen. It is assumed that the building in which the target institution is located is displayed at the center of the screen, and that the building is indicated by the cursor CSR.

0048While the above operation is performed, the menu/information generator 23 generates a setup menu MN to display the setup menu MN on the map such that the setup menu MN overlaps the map. In this manner, a predetermined item of the setup menu MN is selected to perform route searching by using a spot (building) indicated by a cursor as a target place, the spot is registered as a passing point, spot registration is performed, or the detailed building information can be displayed. These operations are in step 202.

0049In this state, when "target place" in the setup menu MN is selected by a remote control operation, route searching is started by using the cursor position as a target place. These operations are in step 203.

0050On the other hand, when "information" is selected from the setup menu MN by a remote control operation, or when a set period of time has elapsed without any operation, the menu/information generator 23 is started. The menu/information generator 23 calculates detailed information DIF including the name, telephone number, address, and location floor number F of a target institution (building user) from the building database stored in the Yellow Page data memory 15, and displays the mane, telephone number, and the address on the left side of the display screen. These operations are in step 204.

0051The display controller 21 performs a birds-eye process to the town map displayed on the right half as in step 104 in FIG. 7 and displays the town map such that the map is gradually inclined. Upon completion of the inclining operation, the display controller 21 calculates the number of floors of the building indicated by the cursor CSR from the building database, raises the building with a height corresponding to the number of floors, and three-dimensionally displays the building BL. The display controller 21 displays the floor number in the three-dimensional building BL by the L-shaped mark FL on the basis of the floor number F of a floor on which a user is located such that the floor number can be identified, and, at the same time, the floor number (6F) is displayed by the letters FLC. The floor number may be displayed by only one of the L-shaped mark or letters. These operations are in step 205.

0052When a building (spot indicated by cursor) is set as a target place, the CPU 18 begins to search an optimum route from the vehicle position to the target place. These operations are in step 206.

(e) Birds-eye Process

0053FIGS. 11 to 13 are views for explaining a birds-eye process and display birds-eye views obtained when a point above a point Q'' behind a point P (x₁,y₁) is regarded as a viewpoint, and the building BL is viewed from the viewpoint in a CFD direction.

0054A planar map (planar shapes of buildings and roads) PM is rotated about the point P (x₁,y₁) by θ°. More specifically, map data (x,y) is subjected to a rotational coordinate transformation process by the following equation:<maths id="math0001" num=""><img file="EP0897170A2_D0001.tif" /></maths> FIG. 11B is a planar map PM' obtained after the coordinate transformation.

0055Thereafter, the following projection transformation process is performed behind the point P by using the direction CFD as a direction of a line of sight while a point Q (FIG. 12A) having a predetermined height is regarded as a viewpoint. As shown in FIG. 12A, a point Q (x₁-z₂,y₁,z₁) which is at a point z₂ behind the point P and has a height z₁ is a viewpoint position.

0056When the rotated map is viewed from the viewpoint Q, position data z'' and y'' of a point where a line of sight crosses a Yp - Zp plane are calculated by the projection transformation process. Transformation equations for calculating z'' and y'' are given by the following equations:<maths id="math0002" num=""><math display="block"><mrow><mtable><mtr><mtd><mrow><mtable><mtr><mtd><mrow><mtable><mlabeledtr><mtext>(2)</mtext><mtd><mrow><msub><mrow><mtext>z'' = z</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext> (x' - x</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext>)/(x' - x</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext> + z</mtext></mrow><mrow><mtext>2</mtext></mrow></msub><mtext>)</mtext></mrow></mtd></mlabeledtr></mtable></mrow></mtd></mtr><mtr><mtd><mrow><mtable><mlabeledtr><mtext>(3).</mtext><mtd><mrow><msub><mrow><mtext>y'' = z</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext> (y' - y</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext>)/(x' - x</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext> + z</mtext></mrow><mrow><mtext>2</mtext></mrow></msub><mtext>) </mtext></mrow></mtd></mlabeledtr></mtable></mrow></mtd></mtr></mtable></mrow></mtd></mtr></mtable></mrow></math><img file="EP0897170A2_D0002.tif" /></maths> For this reason, map data (x',y') of all rotated points which are present before the viewpoint within a view angle of ±45° are transformed by equations (2) and (3) into a coordinate value (y'',z'') of a Yp - Zp coordinate system.

0057Equations (2) and (3) can be obtained by the following manner with reference to FIGS. 12B and 12C. More specifically, with reference to FIG. 12B, a Yp-axis coordinate value y'' of an arbitrary point M' (x',y') after rotation on the Yp - Zp plane satisfies the following equation by the similarity of triangles:<maths id="math0003" num=""><math display="block"><mrow><msub><mrow><mtext>(x' - x</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext> + z</mtext></mrow><mrow><mtext>2</mtext></mrow></msub><msub><mrow><mtext>) : (y' - y</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext>) = z</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext> : y''.</mtext></mrow></math><img file="EP0897170A2_D0003.tif" /></maths> For this reason, when Y'' is calculated, equation (3) can be obtained. With reference to FIG. 12C, a Zp-axis coordinate value z'' of an arbitrary point M' after rotation on the Yp - Zp plane satisfies the following equation by the similarity of triangles:<maths id="math0004" num=""><math display="block"><mrow><msub><mrow><mtext>(x' - x</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext> + z</mtext></mrow><mrow><mtext>2</mtext></mrow></msub><msub><mrow><mtext>) : z</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext> = (x' - x</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext>) : = z''.</mtext></mrow></math><img file="EP0897170A2_D0004.tif" /></maths> For this reason, when z'' is calculated, equation (2) can be obtained. When the projection transformation process is completed as described above, a birds-eye view is generated by using the obtained graphic data (y'',z'') to display the birds-eye view. FIG. 13 is a view for explaining the birds-eye view.

0058Although the present invention has been described above with reference to the embodiment, various modification of the present invention can be effected without departing from the spirit and scope of the invention, and the present invention does not exclude these modifications.

0059As described above, according to the present invention, since the floor number, in a building, on which a target institution is located is displayed, a user can be reliably guided to the target institution.

0060According to the present invention, a building is three-dimensionally displayed, and the location floor number of a target institution is displayed by an L-shaped mark in the three-dimensional building. For this reason, the presence/absence of the target institution in the building and the floor number of a floor on which the target object is located can be visually simply displayed.

0061According to the present invention, an actual building, even if the number of floors in an actual building is large, can be displayed without sticking out of a screen, and a building, even if the number of floors in the building is small, can be three-dimensionally displayed with a proper height.

0062According to the present invention, even if a target institution is located in the basement of a building, the floor number in the basement is displayed, and the location position of the target institution can be easily recognized.