JP2006155603A - Map information providing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the number of icons to be displayed appropriately so that visibility of a map and convenience do not deteriorate when icons overlap. <P>SOLUTION: An icon control table 17 of the map information providing system 10 stores in advance a display control table 18 and a display control record 19 for regulating which category of icons are displayed every display level (reduced scale level) of a mesh file and which category of icons are not displayed. Thus, in accordance with the display level of a map image, a category of icon to be displayed is determined, the total number of icons is limited, and the visibility of the map is secured. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a map information providing system that displays icons indicating stores, facilities, etc. in a superimposed manner on a map.

  For example, a service for transmitting a map image to a user information terminal (personal computer, portable information terminal, cellular phone, etc.) via a communication network such as the Internet is conventionally known.

  In such a map information providing service, when a user accesses a map information service server via an information terminal and inputs a search condition such as an address, a telephone number, or a landmark, a map image of a predetermined range is generated. Are transmitted to the information terminal of the user and displayed on the screen of the information terminal.

  Here, on the map image, not only basic display elements such as mountains, rivers, roads, and address notation, but also peripheral information and base guidance information are displayed as image data such as icons and character data. As base guidance information, the icon which guides stores and facilities, such as a bank, a convenience store, a gas station, a hospital, a temple, a parking lot, can be mentioned, for example.

  By displaying icons overlaid on the map, the user can use them as landmarks and life information on the map, while the store or facility side can aim for advertising effects. In particular, since icons are displayed regardless of the size on the map, smaller stores and facilities are more advantageous in terms of advertising.

  In addition to simply displaying an icon, a technique is also known in which detailed information of the store or facility is associated with the icon and, for example, the detailed information associated with the icon is displayed by selecting the icon. ing.

  A technique is known in which the number of icons to be displayed is changed depending on whether the map is enlarged or reduced (see, for example, Patent Document 1). Further, a technique for holding a plurality of map data having different scales and displaying a map corresponding to the scale is known (see, for example, Patent Document 2).

Japanese Patent No. 2999166

Japanese Patent No. 2671393

  In this way, the icon displayed on the map image is useful, but depending on the case, it may be difficult to see due to overlapping icons, or roads, rivers, etc. may be hidden under the icon, and function as a map. May be partially lost.

  For example, if the scale size is reduced, such as “1 / 50,000”, a wide range is displayed. However, when a city area having a large number of icons is included in the display range, the icons are concentrated in the city area. , Looks and visibility decreases.

  Therefore, it is possible to consider a method of selectively displaying several types of icons from among many types of icons. For example, when thinking mainly by the user, only a specific type of icon desired by the user can be selected and displayed. On the other hand, when considering from the store or facility side, for example, it is also conceivable to select and display only an icon indicating a specific store or the like that focuses on advertising.

  In addition, it is conceivable to allow the icons to be overlapped and to display a list of the names of the shops and facilities indicated by the overlapping icons at the place where the icons overlap and wait for the user's selection.

  However, when simply selecting the type of icon to be displayed according to the user's request, the number of icons included in the map image can be reduced, but it may be concentrated in a specific area depending on the characteristics of the icon. , May not solve the problem. For example, there are cases where stores and facilities of the same type are densely located in a specific area, such as Buddhist altar tools, commercial kitchen equipment, electric appliances, restaurants, and the like.

  Further, when the purpose of use (use) of the map is to grasp the outline of a predetermined area, it is preferable to display as many types of icons as possible. In this case, browsing the map image while switching a specific type of icon and grasping the outline is complicated and inconvenient.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a map information providing system capable of improving visibility and usability by appropriately controlling icon display in consideration of the scale size. Is to provide. Further objects of the present invention will become clear from the embodiments described later.

  In order to solve the above problems, in the map information providing system according to the present invention, map information management means for storing and managing map information, map information by referring to the input position and scale size, and a map image of a predetermined range The drawing control means for drawing the image, the icon information management means for storing and managing the position and type of the store / facility on the map and icon data, and the type of icon to be displayed for each scale size of the map image to be displayed in advance Icon display control information management means for storing and managing set icon display control information, and the input position of an icon to be displayed on the map image drawn by the drawing control means with reference to the icon display control information According to the scale size and the icon data of the determined icon is read from the icon information management means and the location of the map image is read. It includes an icon control means for displaying superposed on position.

  When the user inputs position information such as an address and coordinates and a scale size, map information in a predetermined range is read based on the input position and scale size, and a map image is drawn. On this map image, icons are arranged at predetermined positions.

  Here, the “store / facility icon” is a representation of a geographical target visually symbolized by a small image. Specifically, for example, an office, a post office, a hospital, a police station, etc. , Fire department, library, school, bank, aquarium, park, zoo, botanical garden, station, airport, parking lot, amusement park, theme park, historic site, parking area, gas station, cinema, theater, restaurant, department store, supermarket, convenience store It is a small picture that symbolizes various stores and facilities such as stores, racetracks, and pachinko parlors. The position (coordinates), type, and image data of the store or facility indicated by each icon are managed by icon information management means.

  The icon display control information defines which type of icon is displayed for each scale size of the map image. For example, when the number of icon types is J1 to J5, when the scale size is 1 / 10,000, the icons of J1 and J2 are displayed, and when the scale size is 1 / 25,000, J1 is displayed. , J3 and when the scale size is 1 / 50,000, the type of icon to be displayed for each scale size can be set as appropriate, such as displaying J4 and J5.

  The icon control means reads the data of a specific type of icon determined to be displayed in advance by referring to the icon display control information based on the scale size of the map image, and arranges it at a predetermined position on the map image. To do. Accordingly, the total number of icons displayed can be adjusted in accordance with the scale size, and visibility can be ensured and usability can be improved.

  In one aspect of the present invention, the icon display control information is classified into a plurality of patterns in advance according to the characteristics of the map information.

  “Characteristics of map information” means the geographical features of the area included in the map information. Specifically, for example, the map information includes urban areas with many stores and facilities, or includes urban areas. It can be mentioned whether the map information is not in the suburbs or mountain seas. Or, for example, whether or not a certain type of icon is excessively concentrated, such as Akihabara in Tokyo and Nihonbashi in Osaka. In other words, whether the map information has a large total number of icons or the map information has a small total number of icons. Can also be shown. Thus, for example, icon display control information is generated in a pattern that restricts icon types in urban map information, and icon display control information is generated in a pattern that includes many icon types in suburban map information. The

  For example, when considering a case where one map image is composed of a part of four pieces of map information (foliage), the number of icons to be displayed is controlled according to the characteristics of each original map information. Therefore, the icon type is suppressed and the icon is displayed in the urban area in the map image, and various types of icons are displayed in the suburb portion in the same map image. Thereby, in the same map image, visibility can be maintained in urban areas, and various types of icons can be displayed in the suburbs to grasp the state of the area in detail.

  In another aspect of the present invention, the icon display control information is classified into a plurality of patterns in advance according to the characteristics and use of the map image.

  “Use of map image” means the purpose of the user to use the map image. For example, survey of refueling points and rest points on the drive route used for examining tourist attractions at the destination as part of the travel plan. Can be used to grasp the progress of the area, etc. As described above, by generating icon display control information in a plurality of patterns from the viewpoint of the use and characteristics (icon density) of the map image, more appropriate icon display control can be performed according to the purpose of use.

  Furthermore, in one aspect of the present invention, the icon display control information includes basic policy information that defines which type of icon is displayed for each scale size, and is not classified into any of a plurality of patterns. Information is processed based on display control information dynamically generated from basic policy information.

  A plurality of icon display control information can be prepared in advance, but when map information that is not classified into any of the patterns is used, the display control information is dynamically generated based on the basic policy information. Once generated, the display control information can be saved and reused. As described above, even when uncategorized map information is displayed, the number of icons to be displayed can be appropriately adjusted by dynamically generating the display control information based on the basic policy information. This also saves the trouble of generating icon display control information based on the characteristics and applications of all of the map information in advance, and further, the map image is newly created from the map information. In the case of generation, the number of displayed icons can be adjusted. The map information has a characteristic that changes one after another, but it can cope with the change of the map information by dynamically generating the display control information.

  According to another aspect of the present invention, there are provided a map information management unit that stores and manages map information, a drawing control unit that draws a map image of a predetermined range by referring to the map information according to an input position and a scale size, and a map Icon information management means for storing and managing the location and type of the store / facility and icon data above, and icon type priority for storing and managing the icon type priority table for the priority of the type of icon to be displayed Display control information that dynamically generates display control information so that the number of icons to be displayed becomes a predetermined value by referring to the priority table by icon type when the position and scale size are input from the table management means and the user Based on the generation means and the generated display control information, icon data is read from the icon information management means, and an icon is displayed at a predetermined position of the map image. An icon controller for displaying superimposed, a map information providing system characterized by comprising a.

  In the present invention, map information is not classified and information for controlling the display of icons is not created in advance, but each time a user inputs a position and a scale size, the icon type priority table is referred to and displayed. Display control information is dynamically generated so that the number of icons to be set becomes a predetermined value. By displaying an icon based on this display control information, appropriate icon display control can be performed, and various map information can be handled.

  The present invention can also be understood as a computer program. The program can be distributed in a fixed manner on a recording medium such as a CD-ROM, DVD-ROM, HDD, or memory, or can be distributed via a communication network.

  As described above in detail, according to the present invention, it is possible to adjust the type of icon to be displayed according to the scale size, and to improve the usability while maintaining the visibility by limiting the number of icons.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 6 relate to the first embodiment of the present invention, and FIG. 1 is an explanatory diagram showing the general outline of the map information providing system.

  The map information providing system (hereinafter also referred to as a system) 10 is formed, for example, as a three-layer structure including a user interface layer, a logic layer, and a database layer, and a large number of information terminals 30 via a communication network CN such as the Internet. It is connected so that it can communicate bidirectionally. As will be described later, the system 10 includes a search unit 11, a drawing control unit 12, an icon control unit 13, a map database 14, an icon file 15, a store / facility file 16, and an icon control table 17. Note that the units 11 to 17 constituting the system 10 do not have to be realized on the physically same computer, and the system 10 can be constituted by cooperative work of a plurality of distributed computers.

  The search unit 11 is for a user to input search conditions in order to obtain a desired map image. Examples of the search method include a postal code, a telephone number, an address, a landmark, a geographical administrative division, and the like. The center coordinates of the map image are determined by these addresses and administrative divisions.

  The drawing control unit 12 draws and generates a map image provided to the user. The drawing control unit 12 detects a mesh file (foliage) necessary for generating a map image from the map information database 14 based on the scale size and center coordinates designated by the user, and has a predetermined size (for example, 500 dots). × 500 dots) is generated.

  The icon control unit 13 refers to the display control table 18, display control record 19, priority table 20, and basic policy table 21 stored in the icon control table 17 to identify the icon to be displayed and arrange it at a predetermined position. And superimposed on the map image.

  The map information database 14 is configured by hierarchizing a large number of mesh data with different scale sizes, such as a national map, a prefecture map, a municipal map, and a city map. The mesh file is specified by the information of.

  The icon file 15 stores image data of each icon. In addition, the store / facility file 16 includes a classification (hereinafter also referred to as “genre”) that classifies stores and the like (hereinafter, stores and facilities may be referred to as “stores”), and the location (icons) (Position information to be installed), icon files symbolizing each store and the like are stored in association with each other. The icon file 15 and the store / facility file 16 may be integrated.

  The icon control table 17 includes information for narrowing down icons to be superimposed on the map image. Details of the icon control table 17 will be described later with reference to FIGS.

  The user information terminal 30 is realized as, for example, a personal computer, a portable information terminal, a mobile phone, or the like, and includes a display unit 31 for browsing a map image and an input unit 32 for inputting search conditions and the like. I have.

  FIG. 2 is an explanatory diagram showing the configuration of the display control table 18 and the display control record 19. As shown in FIG. 2A, display group numbers are associated with the display control table 18 for each figure number x, y for specifying each mesh file.

  Next, as shown in FIG. 2B, the display control record 19 displays which genre icon at which display level (scale level) and non-display at which display level for each display group number. It defines what to do. Symbols J001 to Jn shown in the figure indicate icon genres. The display level L becomes larger as the subscript number increases. For example, focusing on the display group number 001, the icons belonging to the icon genre J002 are not displayed at the display levels L1, L2, but are displayed at the display levels L3, L4,. Specifically, for example, each icon belonging to the genre “convenience store” can be defined for each display level so that it is displayed at a certain display level and not displayed at another display level. Display group numbers are set for each pattern.

  Therefore, by referring to the display group number described in the display control table 18 shown in FIG. 2A, any genre icon among the icons included in the mesh file is displayed, and any genre icon. Can be easily known. That is, the display group number assigned to each mesh file indicates an icon display pattern in the mesh file.

  Note that the display control record 19 shown in FIG. 2B may be stored as it is, but in that case, a large amount of storage area is consumed. Therefore, the display / non-display setting pattern at each display level for each icon genre is examined, a pattern number is assigned to each setting pattern, and only the pattern number is described in the same pattern portion. Thereby, the storage amount can be reduced.

  Next, as shown in FIG. 3A, the priority table 20 predefines display priority for each icon genre. In the figure, a genre having a high priority is positioned on the upper side of the table, and the priority decreases as it goes downward.

  FIG. 3B shows the configuration of the basic policy table 21. The basic policy table 21 indicates the initial setting of icon display. For mesh files that are not associated with display group numbers, the display / non-display of icons is determined by referring to the basic policy table 21. The pattern of each display group is generated by adding or deleting an icon genre based on the basic policy table 21. The basic policy table 21 can also be provided in the display control record 19. For example, the display group number “000” may be the default basic group number, and the basic group number may be associated with all mesh files as long as another display group number is not assigned.

  FIG. 4 is a flowchart showing an overview of the generation process of the display control table and the display control record. Hereinafter, the step is abbreviated as “S”.

  This process is performed for each predetermined figure leaf (mesh file) (S1), and information on all icons included in the set mesh file is detected (S2).

  Next, the number of displayable basic icons is detected for each display level (S3). The number of basic icons is predetermined for each display level, and indicates the upper limit of the number of icons that can be appropriately displayed at that display level. For example, at display level L5, 1/4 of the mesh file is used to generate a 500 dot × 500 dot map image, and at the display level L6, 1/4 of the mesh file is used to generate a map image of the same size. Assume that 8 is used. If the total number of icons displayed per 500 × 500 dot map image is limited to 100, the number of basic icons at the display level L5 is 400, which is four times the number of basic icons at the display level L6. Doubled to 800. As the scale increases, the number of basic icons increases and the total number of icons that can be displayed increases.

  Next, the number of basic icons at each display level is compared with the total number of icons to be displayed defined in the basic policy table 21 among all types of icons included in the mesh file (S4). As described above, the basic policy table 21 defines which genre icon is displayed and which genre icon is hidden at each display level. Therefore, the icons of the genre set as “display” are display target icons, and the total number of icons to be displayed is compared with the number of basic icons which is the upper limit value.

  If the total number of icons to be displayed substantially matches the number of basic icons, the display control record 19 is described so as to display icons of all genres included in the mesh file, and the display group number is displayed in the display control table. 18 is registered.

  On the other hand, when the total number of icons to be displayed included in the mesh file is less than the number of basic icons, the priority table 20 is referred to, and the basic policy table 21 has the highest priority among the genres set to be hidden. Add icons of high genres to "Display". This genre addition operation is repeated until the total number of displayed icons substantially matches the number of basic icons, and a display control record is created (S6).

  When the total number of icons to be displayed included in the mesh file exceeds the number of basic icons, the genre having the lowest priority among the genres set to “display” in the initial setting of the basic policy table 21 is “non-display”. Set to “Display”. This genre reduction operation is repeated until the total number of icons to be displayed substantially matches the number of basic icons. Then, as described above, a display control record is created, and the display group number is associated with the mesh file (S7).

  By performing the above processing for a predetermined mesh file, the genre of the icon displayed at each display level can be defined in advance for each display level of each mesh file.

  Note that it is not necessary to perform the above-described grouping for all mesh files. It is only necessary to perform the above processing for a specific mesh file including a region where the icon display is to be adjusted, such as a city area having a large number of genres and icons that are likely to be crowded, or a suburb where icons are to be displayed.

  Thus, after determining the genre of the icon which should be displayed for every display level about a predetermined mesh file, the process when there is a map information provision request from a user is referred to the flowchart of FIG. explain.

  First, the figure number of the mesh file used for map image generation is specified from the center coordinates and display size of the map image desired by the user (S11).

  Next, referring to the display control table 18 from the figure number (S12), whether or not a display group number is set in the mesh file, that is, whether or not a display control record adjusted for the mesh file has been generated. Is determined (S13).

  If a display control record is set in the mesh file, an icon to be displayed is selected and read in accordance with the setting contents of the display control record, and is drawn over the map image (S14).

  On the other hand, if no display control record is set in the mesh file, the basic policy table 21 is referred to at the specified display level, and the display control table for display control non-setting is dynamically set according to the flowchart described above with reference to FIG. To generate. Then, based on the dynamically generated display control table (S15), among the icons of all genres associated with the mesh file, the icon of the genre set to “display” at the display level is read. Then, it is displayed superimposed on the map image (S16).

  Thereby, for example, a map image as shown in FIG. 6 can be obtained. As shown in FIG. 6A, consider a case where one map image is generated from each part of four mesh files MF1 to MF4. The mesh file MF1 is map data including “city” having a large number of genres and a large number of icons belonging to each genre. The mesh file MF2 has a large number of genres but the number of icons in each genre. It is assumed that the map data includes “suburbs” having a characteristic of being small.

  The display control record of the mesh file MF1 including the urban area is set by narrowing the number of genres so that the icons are dense and the visibility is not impaired, and the display control record of the mesh file MF2 including the suburb indicates the state of the area. In order to make it easier to grasp, it is set to display icons of more genres.

  Therefore, as shown in FIG. 6B, in the same map image, the portion A1 derived from the mesh file MF1 has a small number of icons to be displayed and is displayed in the portion A2 derived from the mesh file MF2. Although there is not much difference in the total number of icons, the number of genres is larger than A1. It is assumed that the mesh files MF3 and MF4 are areas without features, and the icon display is controlled according to the basic policy table 21.

  As described above, according to the present embodiment, the icon genre to be displayed for each display level of each mesh file is set in advance and the total number of icons to be displayed is adjusted. By limiting the number of display genres in a region with many icons and increasing the number of genres to be displayed in a region with few icons, it is possible to provide a user with a more convenient map image.

  Moreover, since the display control record 19 is generated according to the characteristics of the mesh file, it is possible to display the display control record 19 with the number of icons more appropriately limited. For example, in a mesh file of a characteristic region with a large number of icons belonging to a specific genre, such as “Akihabara” where electronics stores are concentrated, by setting the specific genre to be hidden, the basic geography The structure (location of roads and public facilities, etc.) can be easily grasped. On the contrary, if the specific genre is set to be displayed, the arrangement of the road may be difficult to understand, but the characteristics of the area can be clearly expressed.

  Next, FIG. 7 shows the configuration of the priority table 20 and the display control record 19 employed in the second embodiment of the present invention. The feature of this embodiment is that the number of icons to be displayed is controlled in consideration of not only the regional characteristics but also the purpose of use of the user (use of map image).

  As shown in FIG. 7A, the priority table 20 is prepared for each use such as “travel”, “shopping”, “learning”, and the like, and is displayed with priority for each use. Icon genre is set. For example, in the priority table of “travel”, a high priority is given so that icons deeply related to travel, such as stations, airports, ferry landings, and hotels, are displayed with priority. In the “shopping” priority table, a high priority is set for an icon deeply related to shopping, such as a department store or a bank. Furthermore, in the “learning” priority table, for example, icons related to learning such as “historic sites” and “library” are given high priority.

  As shown in FIG. 7B, display control records 19 are also generated for each application.

  Thereby, when the user designates the purpose of use and requests a map image, the genre of the icon to be displayed can be controlled according to the use and the display level, and the usability can be further enhanced.

  The present invention is not limited to the above embodiments. Those skilled in the art can make various modifications such as adding new additions or changes to the configuration of each embodiment. Further, the display / non-display of the icon genre shown in the drawing is merely an example for explanation, and the present invention is not limited to this.

1 is a block diagram showing an overall outline of a map information providing system according to a first embodiment of the present invention. It is explanatory drawing which shows the structure of a display control table and a display control record. It is explanatory drawing which shows the structure of a priority table and a basic policy table. It is a flowchart which shows the production | generation process of a display control table and a display control record. It is a flowchart which shows an icon display control process. It is explanatory drawing which shows a mode that a map image is produced | generated from a some mesh file. It is explanatory drawing which shows the structure of the priority table classified by use used in the 2nd Embodiment of this invention, and a display control record.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Map information provision system 11 Search part 12 Drawing control part 13 Icon control part 14 Map database 15 Icon file 16 Store / facility file 17 Icon control table 18 Display control table 19 Display control record 20 Priority table 21 Basic policy table 30 Information terminal

Claims (7)

Map information management means for storing and managing map information;
Drawing control means for drawing a map image of a predetermined range with reference to the map information by the input position and scale size;
Icon information management means for storing and managing the position and type of icons to be displayed on the map;
Icon display control information management means for storing and managing a display control table that associates the types of icons to be displayed for each scale size of the map image to be displayed;
With reference to the icon display control information and the display control table, an icon to be displayed on the map image drawn by the drawing control means is determined according to the scale size, and the determined icon is set at a predetermined position of the map image. Icon control means for displaying in a superimposed manner;
A map information providing system characterized by comprising:   The map information providing system according to claim 1, wherein the icon display control information is classified in advance into a plurality of patterns according to the total number or density of all types or specific types of icons included in the map information.   The map information providing system according to claim 1, wherein the icon display control information is classified into a plurality of patterns in advance according to the use of the map image. A basic policy management means for storing and managing a basic policy table that associates each scale size of the map image to be displayed with the type of icon to be displayed in the scale size;
Priority management means for storing and managing a priority table that associates each icon type with its priority;
Icon detection means for detecting, from the icon information management means, information relating to all icons included in the map area represented by the map information;
At each scale size, the number of icons that can be appropriately displayed on a predetermined map (hereinafter referred to as “number of basic icons”), and the icon that is defined in the basic policy table among icons detected by the icon detection means. The total number of types of icons (hereinafter referred to as “target icons”) to be displayed in the scale size (hereinafter referred to as “target icons”) is compared,
When the number of target icons matches the number of basic icons or the difference between the two is within a predetermined range, all the types of icons to be displayed at the scale size defined in the basic policy table, Register in the display control table as the type of icon to be displayed at the scale size,
When the number of target icons is less than the number of basic icons, the number of target icons is not displayed in the basic policy table until the number of target icons matches the number of basic icons or the difference between the two is within a predetermined range. After adding to the target icon in order from the icon with the highest priority among the types of icons that are present, the type of the target icon is registered in the display control table as the type of icon to be displayed at the scale size,
If the number of target icons exceeds the number of basic icons, the target policy number is displayed in the basic policy table until the number of target icons matches the number of basic icons or the difference between the two is within a predetermined range. A display that registers the type of the target icon in the display control table as the type of icon to be displayed at the scale size after deleting from the target icon in order from the icon with the lowest priority among the types of icons that are present The map information providing system according to any one of claims 1 to 3, further comprising a control table registration / updating unit. A function for drawing a map image of a predetermined range with reference to the map information managed by the map information management means according to the input position and scale size;
A function of registering in the icon display control information management means a display control table that associates the types of icons to be displayed for each scale size of the map image to be displayed;
Referring to the icon display control information and the display control table, an icon to be displayed on the drawn map image is determined according to a scale size, and predetermined icon data is displayed at a predetermined position on the map image. Function
A program to implement on a computer. Map information management means for storing and managing map information;
Drawing control means for drawing a map image of a predetermined range with reference to the map information by the input position and scale size;
Icon information management means for storing the position and type of icons to be displayed on the map;
A priority table management means for storing and managing a priority table that associates each icon type with its priority;
Display control information generation that dynamically generates display control information so that the number of icons to be displayed or the density of icons is not more than a predetermined value with reference to the priority table when a position and a scale size are input from a user Means,
Icon control means for reading icon data from the icon information management means based on the display control information and displaying the icon superimposed on a predetermined position of the map image;
A map information providing system characterized by comprising: A function for drawing a map image of a predetermined range with reference to the map information managed by the map information management means according to the input position and scale size;
When the position and scale size are input from the user, the number of icons displayed on the map image or the density of the icons can be determined by referring to a priority table that associates each icon type with its priority. A function for dynamically generating display control information to be below a predetermined value;
A function of reading icon data managed by icon information management means based on the display control information, and displaying an icon superimposed on a predetermined position of the map image;
A program to implement on a computer.

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