Abstract:
A method is described of selecting one of a plurality of zoom levels of a desired map, the map comprising a plurality of data points and each zoom level comprising at least a portion of the data points, the zoom levels ranging from low magnification to high magnification, including selecting ( 802, 912 ) a zoom level having a number of data points beyond a threshold. The selecting ( 802, 912 ) a zoom level may occur subsequent to selecting ( 910 ) a previous map having a plurality of data points wherein each of the zoom levels of the desired map and the previous map include a distinctive number of the data points.

Description:
FIELD 
       [0001]    The present invention generally relates to a method of selecting maps on an electronic display and more particularly to a method for selecting the degree of zoom when switching from one map to another. 
       BACKGROUND 
       [0002]    Modern map displays, particularly those used in aircraft for flight planning and monitoring, are capable of displaying a considerable amount of information such as terrain information and flight planning information. The terrain information may include situational awareness terrain and cautions that identify potential hazards. Flight planning information may include, for example, flight path and altitude information useful to the pilot. 
         [0003]    Three dimensional perspective representations of terrain and flight planning information provide better spatial understanding and situation awareness and therefore reduce the navigational workload for a flight crew. A flight path display with a terrain underlay will also significantly enhance the perception of depth and relative location during the flight path visualization therefore reducing flight crew work load and improving the vertical awareness relative to terrain. 
         [0004]    These electronic instrumentation displays continue to advance in sophistication, achieving increasingly higher levels of information density and, consequently, presenting a greater amount of visual information to be perceived and understood by the operator, e.g., pilot. It is important that visual displays provide a proper cognitive mapping between what the operator is trying to achieve and the information available to accomplish the task. As a result, displays, especially aircraft displays, tend to be populated with numerous, non-intuitive icons and symbols. 
         [0005]    The operator may have many map options available, including aviation maps including, e.g., desired flight path, terrain maps including, e.g., ground obstacles, surface street maps, and the like. In some situations, such as moving map displays, as the operator&#39;s distance from the desired geographic target varies, the electronic display may zoom in or zoom out to show more or less detail. However, if the operator desires to switch to another map, for example from a aviation map to a street map, the zoom level may be at an undesired level showing too much or too little detail. 
         [0006]    Accordingly, it is desirable to provide a method for automatically selecting the degree of zoom when switching from one map to another. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    A method is described of selecting one of a plurality of zoom levels of a desired map, the map comprising a plurality of data points and each zoom level comprising at least a portion of the data points, the zoom levels ranging from low magnification to high magnification, including selecting a zoom level having a number of data points beyond a threshold. The selecting of a zoom level of a desired map may occur when initially accessing a map or subsequent to selecting a previous map wherein each of the zoom levels of the desired map and the previous map include a distinctive number of the data points. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Embodiments of the present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and 
           [0009]      FIG. 1  is a functional block diagram of a flight display system in accordance with an exemplary embodiment; 
           [0010]      FIG. 2  is an exemplary image of a terrain map that may be rendered on the flight display system of  FIG. 1 ; 
           [0011]      FIG. 3  is an exemplary image of a topographical map that may be rendered on the flight display system of  FIG. 1 ; 
           [0012]      FIG. 4  is an exemplary image of a first zoom level of an aviation map that may be rendered on the flight display system of  FIG. 1 ; 
           [0013]      FIG. 5  is an exemplary image of a first zoom level of a road map that may be rendered on the flight display system of  FIG. 1 ; 
           [0014]      FIG. 6  is an exemplary image of a second zoom level of a road map that may be rendered on the flight display system of  FIG. 1 ; 
           [0015]      FIG. 7  is an exemplary image of a third zoom level of a road map that may be rendered on the flight display system of  FIG. 1 ; 
           [0016]      FIG. 8  is an exemplary image of a second zoom level of an aviation map that may be rendered on the flight display system of  FIG. 1 . 
           [0017]      FIG. 9  is a first flow chart of the steps of the exemplary embodiment; and 
           [0018]      FIG. 10  is a second flow chart of the steps of the exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
         [0020]    The mapping methods described herein may be applied to a variety of applications, such as automobile, marine, and aviation; however, an aviation environment is described herein as the exemplary embodiment and may include navigation from point to point or approach and landing at an airport. Various types of maps may be used, for example, road maps, terrain maps, aviation maps, and topographical maps. 
         [0021]    Some applications may require more than one monitor, for example, a head down display screen, to accomplish the mission. These monitors may include a two dimensional moving map display and a three dimensional perspective display. A moving map display may include a top-down view of the aircraft, the flight plan, and the surrounding environment. Various symbols are utilized to denote navigational cues (e.g., waypoint symbols, line segments interconnecting the waypoint symbols, range rings) and nearby environmental features (e.g., terrain, weather conditions, political boundaries, etc). 
         [0022]    The moving map display and the perspective display each provide a pilot (or other observer) with important navigational information. For example, the moving map display permits a pilot to easily determine the aircraft&#39;s location with reference to geographical landmarks, including significant geographical features (e.g., ridges, mountain ranges, valleys, etc.) and man-made structures (e.g., airports). Consequently, a pilot may refer to the moving map display when guiding an aircraft to a particular destination. The perspective display, by comparison, provides information regarding the aircraft&#39;s orientation (e.g., the aircraft&#39;s attitude, altitude, pitch, roll, etc.) and aspects of nearby geographical features in an intuitive manner. Thus, a pilot may refer to the perspective display when navigating around a geographical feature, such as a mountain. 
         [0023]    Alternate embodiments of the present invention to those described below may utilize whatever navigation system signals are available, for example a ground based navigational system, a GPS navigation aid, a flight management system, and an inertial navigation system, to dynamically calibrate and determine a precise course. 
         [0024]    Referring to  FIG. 1 , an exemplary flight deck display system is depicted and will be described. The system  100  includes a user interface  102 , a processor  104 , one or more terrain databases  106 , one or more navigation databases  108 , various sensors  112 , various external data sources  114 , and a display device  116 . The user interface  102  is in operable communication with the processor  104  and is configured to receive input from a user  109  (e.g., a pilot) and, in response to the user input, supply command signals to the processor  104 . The user interface  102  may be any one, or combination, of various known user interface devices including, but not limited to, a cursor control device (CCD)  107 , such as a mouse, a trackball, or joystick, and/or a keyboard, one or more buttons, switches, or knobs. In the depicted embodiment, the user interface  102  includes a CCD  107  and a keyboard  111 . The user  109  uses the CCD  107  to, among other things, move a cursor symbol on the display screen (see  FIG. 2 ), and may use the keyboard  111  to, among other things, input textual data. 
         [0025]    The processor  104  may be any one of numerous known general-purpose microprocessors or an application specific processor that operates in response to program instructions. In the depicted embodiment, the processor  104  includes on-board RAM (random access memory)  103 , and on-board ROM (read only memory)  105 . The program instructions that control the processor  104  may be stored in either or both the RAM  103  and the ROM  105 . For example, the operating system software may be stored in the ROM  105 , whereas various operating mode software routines and various operational parameters may be stored in the RAM  103 . It will be appreciated that this is merely exemplary of one scheme for storing operating system software and software routines, and that various other storage schemes may be implemented. It will also be appreciated that the processor  104  may be implemented using various other circuits, not just a programmable processor. For example, digital logic circuits and analog signal processing circuits could also be used. 
         [0026]    No matter how the processor  104  is specifically implemented, it is in operable communication with the terrain databases  106 , the navigation databases  108 , and the display device  116 , and is coupled to receive various types of inertial data from the various sensors  112 , and various other avionics-related data from the external data sources  114 . The processor  104  is configured, in response to the inertial data and the avionics-related data, to selectively retrieve terrain data from one or more of the terrain databases  106  and navigation data from one or more of the navigation databases  108  (including surface features such as roads), and to supply appropriate display commands to the display device  116 . The display device  116 , in response to the display commands, selectively renders various types of textual, graphic, and/or iconic information. The preferred manner in which the textual, graphic, and/or iconic information are rendered by the display device  116  will be described in more detail further below. Before doing so, however, a brief description of the databases  106 ,  108 , the sensors  112 , and the external data sources  114 , at least in the depicted embodiment, will be provided. 
         [0027]    The terrain databases  106  include various types of data representative of the terrain over which the aircraft is flying, and the navigation databases  108  include various types of navigation-related data. These navigation-related data include various flight plan related data such as, for example, waypoints, distances between waypoints, headings between waypoints, data related to different airports, navigational aids, obstructions, special use airspace, political boundaries, communication frequencies, and aircraft approach information. It will be appreciated that, although the terrain databases  106  and the navigation databases  108  are, for clarity and convenience, shown as being stored separate from the processor  104 , all or portions of either or both of these databases  106 ,  108  could be loaded into the RAM  103 , or integrally formed as part of the processor  104 , and/or RAM  103 , and/or ROM  105 . The terrain databases  106  and navigation databases  108  could also be part of a device or system that is physically separate from the system  100 . 
         [0028]    The sensors  112  may be implemented using various types of inertial sensors, systems, and or subsystems, now known or developed in the future, for supplying various types of inertial data. The inertial data may also vary, but preferably include data representative of the state of the aircraft such as, for example, aircraft speed, heading, altitude, and attitude. The number and type of external data sources  114  may also vary. For example, the external systems (or subsystems) may include, for example, a terrain avoidance and warning system (TAWS), a traffic and collision avoidance system (TCAS), a runway awareness and advisory system (RAAS), a flight director, and a navigation computer, just to name a few. However, for ease of description and illustration, only an instrument landing system (ILS) receiver  118  and a global position system (GPS) receiver  122  are depicted in  FIG. 1 . 
         [0029]    The display device  116 , as noted above, in response to display commands supplied from the processor  104 , selectively renders various textual, graphic, and/or iconic information, and thereby supply visual feedback to the user  109 . It will be appreciated that the display device  116  may be implemented using any one of numerous known display devices suitable for rendering textual, graphic, and/or iconic information in a format viewable by the user  109 . Non-limiting examples of such display devices include various cathode ray tube (CRT) displays, and various flat panel displays such as various types of LCD (liquid crystal display) and TFT (thin film transistor) displays. The display device  116  may additionally be implemented as a panel mounted display, a HUD (head-up display) projection, or any one of numerous known technologies. It is additionally noted that the display device  116  may be configured as any one of numerous types of aircraft flight deck displays. For example, it may be configured as a multi-function display, a horizontal situation indicator, or a vertical situation indicator, just to name a few. In the depicted embodiment, however, the display device  116  is configured as a navigation display. 
         [0030]    The display device  116  is used to display various images and data, in both a graphical and a textual format, and to supply visual feedback to the user  109  in response to the user input commands supplied by the user  109  to the user interface  102 . It will be appreciated that the display device  116  may be implemented using any one of numerous known display devices suitable for rendering image and/or text data in a format viewable by the user  109 . Non-limiting examples of such display devices include various cathode ray tube (CRT) displays, and various flat panel displays such as, various types of LCD (liquid crystal display) and TFT (thin film transistor) displays. The display device  116  may additionally be implemented as a panel mounted display, a HUD (head-up display) projection, or any one of numerous known technologies. 
         [0031]      FIGS. 2-7  include examples of the types of maps that may be displayed on the display device  116 , wherein the pilot switches from one map to another depending on the flight situation.  FIGS. 2-4  illustrate examples of a terrain map, a topographical map, and an aviation map, respectively. The terrain map of  FIG. 2  includes an aircraft icon  202 , the horizon  204 , and a hill  206 . Each of these items is known as a data point. Although only one zoom level is shown, a larger view of the terrain map (a lower zoom level) could include other data points such as a lake, a river, a mountain, and the like. 
         [0032]    The topographical map of  FIG. 3  displays data points including an aircraft icon  302  and various altitude gradients  308  of the hill  306 . The aviation map of  FIG. 4  displays data points including an aircraft icon  402 , an airport  412 , a VOR navigational aid  414 , a circle  416  indicating a seven mile radius from the VOR  414 , and a restricted area  416 . 
         [0033]      FIGS. 5-7  are road maps of three different zoom levels, where  FIG. 5  is the lowest magnification and includes twelve data points including an aircraft icon  502 , a hill  506 , an airport  512 , a city  522 , a town  524 , a lake  526 , an interstate highway  528 , and roads  531 ,  532 ,  533 ,  534 ,  535 ,  536 .  FIG. 6  is a magnified view (zoomed in) of the map of  FIG. 5  and includes only 10 of the data points of  FIG. 5 , including the aircraft icon  502 , hill  506 , airport  512 , town  524 , lake  526 , and roads  531 ,  532 ,  533 ,  534 ,  535 ,  536 .  FIG. 7  is a further magnified view of the map of  FIG. 5  and includes only 6 of the data points of  FIG. 5 , including the aircraft icon  502 , hill  506 , airport  512 , and roads  531 ,  532 ,  533 ,  534 . 
         [0034]    When selecting the aviation map when another type of map is being displayed, e.g., a road map, and if the zoom level of the displayed map is low (high magnification: few data points are illustrated), it is desirable that the zoom level of the selected map have a sufficient zoom level for the pilots to identify the location. A roadmap is more likely to show details when zoomed way in than the other types of map. One possible scenario is for the pilots to zoom in on the road map in order to locate a particular address. The pilots may want to differentiate objects that may be only tens of feet apart. This would be typical of a police helicopter. Upon finding the location of the house, the pilots may then switch back to the aviation map so that they can locate local radio beacons, landing sites, tall obstacles, etc. However, the current zoom level, while useful for a house location, could show no objects at all in the aviation mode (see  FIG. 8 ). Aviation obstacles and beacons can be miles apart, and usually are. The pilot must now manually zoom out until the map displays enough objects for them to get their bearings, for example,  FIG. 5 ,  6 , or  7 . The method described herein automates that manual process by automatically detecting that no objects will be present and zooming out to a useful level. Therefore, in accordance with the exemplary embodiment, a threshold of a number of data points is identified for each of the types of maps (terrain, topographical, aviation, road). When selecting that particular type of map, the zoom level is displayed that exceeds but is closest to that threshold (within the pilot&#39;s cognitive ability). 
         [0035]    In accordance with the exemplary embodiment and referring to the flow chart of  FIG. 9 , a map is selected  902  wherein a particular zoom level displayed is determined by a number of data points beyond a threshold. This applies to when first turning on the display, or when selecting a map when another map is being displayed as shown in  FIG. 10 , wherein a first map having a plurality of first data points and a plurality of first zoom levels is stored  1002 . The number of first data points for each of the first zoom levels is determined  1004 . A second map having a plurality of second data points and a plurality of second zoom levels is stored  1006  and the number of second data points for each of the second zoom levels is determined  1008 . Having previously selected one of the first zoom levels of the first map, the second map is selected  1010  wherein the particular second zoom level displayed is determined by a number of data points beyond a threshold. 
         [0036]    While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.