OA16974A - Methods and apparatus for identifying geographic locations. - Google Patents

Description

METHODS AND APPARATUS FOR IDENTIFYING

GEOGRAPHIC LOCATIONS

Field of the Invention

Embodiments of the présent invention relate to methods and apparatus for generating identifiers for géographie locations. In particular, embodiments of the invention relate to methods and apparatus for generating identifiers for géographie locations which are optimised for human use, so that locations with, for example, higher population density hâve, on average, shorter identifiers.

Background of the Invention

In many countries locations are uniquely identified with reference to an address which often comprises a street or road name, number and city. For some countries, such as India, there is no centralised address system, or at least any such system is severely limited. It is therefore difficult for a user to Input a location identifier, e.g. représentative of a desired destination, into a navigation device, and other location Identification techniques must be used.

A widely used system to identlfy géographie locations is WGS84 which spécifiés a longitude and latitude for every location on the earth's surface. For example WGS84 coordinates which identify TomTom Headquarters at Oosterdoksstraat 114, Amsterdam, The Nethertands is N52.376513, E 4.908496. However it can be appreciated that WGS84 coordinates are difficult for a user to remember and slow to enter into a navigation device.

It is also known to use alphanumeric codes to Identify locations. One alphanumeric code system is Loc8 codes - www.myloc8ion.com - and which are described In WO 2011/073965 A1. This system uses an eight digit alphanumeric code such as W8L-82-4YK to identify a location to within a 120m square.

A further alphanumeric based system has been developed by Denso Corporation, and which is described In US 6,006,160, In which a région Is divided Into square sections of 900' (274m), each of which Is further divided Into square blocks of 30 (9m), each of which Is divided Into units of a square of Γ (0.12m). Each section is defined with a section code of three figures, each block Is defined with a block code of three figures and each unit is defined with a unit code of three figures so that each unit can be completely differentiated with an Intrinsic code of nine figures formed by section code, “block code, “unit code' concatenated together. It Is also envisaged by US 6,006,160 that section codes may be selectively allocated such that, for example, Tokyo may

-2have a section code of 000 and Osaka may hâve a section code of 001. In this way, when leading 0's are omitted one Intrinslc code (section 000 for Tokyo) can be represented as six digits, whilst some other section codes can be represented as seven digits (e.g, section 001 for Osaka). However it will be appreclated that the number of shorter section codes is limited and only one section code can benefit from having three leading 0’s, I.e. being 000.

It is an object of embodiments of the Invention to at least mitigate one or more of the problems of the prior art.

Su m mary ofthe Invention

In accordance with a first aspect ofthe invention, there is provided a computer-implemented method for assigning identifiers to géographie locations within digital map data, comprising: selecting a région within the map data; dividing the région Into a first plurality of cells each uniquely addressable by an Identifier of a first length; selecting a portion of the région; and dividing the portion into a second plurality of cells each uniquely addressable by an identifier of a second length, wherein the second length is shorter length than the first length and a géographie location within the portion of the région may be uniquely identified by an identifier of the first length and an identifier of the second length.

The portion of the région may be selected based on one or more attributes ofthe map data. One or both of the région and the portion of the région may be selected based upon one or more criteria and the attributes of the map data. The criteria may be Indicative of a population density associated with the digital map data. The région may correspond to a région demarcated in the map data. The method may further comprise selecting one or more further portions ofthe région, and dividing the one or more further portions into further pluralities of cells each uniquely addressable by an identifier of successively short length. A géographie location in each further portion of the région may be identifiable by a plurality of identifiers or different lengths. The région and the one or more portions may be divided into substantially equally sized cells. The identifier may comprise prefix and postfix portions divided by a separator. The identifier may be formed from alphanumeric characters.

The invention further encompasses an apparatus, such as a computing device comprising one or more processors, arranged to perform any or ail of the required and optional steps of the above described method. The présent invention further extends to a, preferably non-transitory, computer program product comprising computer readable instructions exécutable to perform a method according to any of the aspects or embodiments of the invention.

-3ln accordance with a further aspect of the invention, there is provided a context table for identifying géographie locations, comprising: a context identifier associated with a géographie région; Information Identifying a location of a firstly plurality of cells dividing at least a part of the géographie région, each cell being associated with a unique identifier of a first length; and Information Identifying a location of a second plurality of celis dividing one portions of the géographie région, each ceil being associated with a unique identifier of a second length, wherein géographie locations within the second plurality of cells are uniquely identified by Identifiers of the first and second lengths.

The context table may further comprise one or more further pluraiities of cells dividing portions of the géographie région, each cell In each respective plurality of cells being associated with a unique identifier of successively decreasing length. The first and second pluraiities of cells may be associated with the context identifier. The second plurality of cells may be associated with one or more further context identifiers. The context table may further comprise size information Indicating a size of each cell in the first and second plurality of cells. The context table may be generated as a resuit of the above described methods. The context table may be stored on a computer readable medium.

In accordance with another aspect of the Invention, there is provided a navigation device, comprising: a display screen for providing navigation information to a user; and a processor communicably coupled to a data store comprising a context table (e.g. as described above), wherein the processor is arranged to receîve, from a user, at least one identifier, and to détermine at least one géographie location corresponding to the respective identifier from the context table.

The at least one identifier received from the user may be représentative of a desired destination, and the processor is arranged to détermine a route to the géographie location identified by the received identifier. The processor may be arranged to receive a context Identifier from the user, wherein the context Identifier is indicative of a géographie région, and wherein the processor is arranged to détermine the at least one géographie location using the context table based on the received context identifier.

It will be appreciated that any of the further aspects of the invention may include any or ali of the features of the Invention described in relation to any other aspects and embodiments of the invention to the extent they are not mutually inconsistant therewith.

Advantages of these embodiments are set out hereafter, and further details and features of each of these embodiments are defined in the accompanying dépendent claims and elsewhere in the following detailed description.

-4Brief description ofthe drawings

Embodiments of the invention wiil now be described by way of example only, with reference to the accompanyîng figures, in which:

Figure 1 illustrâtes an association of identifiers with a map according to an embodiment of the Invention;

Figure 2 shows an arrangement of identifiers according to an embodiment of the Invention;

Figure 3 shows a method according to an embodiment of the invention;

Figure 4 is an illustration of a country as a géographie région having a plurality of portions selected;

Figure 5 is an Illustration of a city selected as a portion of a géographie région;

Figure 6 is an illustration of the Earth showing géographie régions corresponding to countries Identified;

Figure 7 shows a schematic of a navigation device according to an embodiment of the Invention; and

Figure 8 an illustration of a software stack according to an embodiment of the Invention.

Detailed Description of Preferred Embodiments

Embodiments of the Invention provide a system for uniquely Identifyîng a géographie location to within a predetermined précision using an identifier having a length which is on average as short as possible. That Is, embodiments of the invention facilitate using identifiers for géographie locations which are shorterfor most frequently identified locations, as wili be explained.

Embodiments of the Invention provide a method and apparatus for Identifyîng a géographie location wherein a first portion of a map, such as a country, state, etc, is divided into a first plurality of cells each addressable by a first unique identifier having a first length. A second portion of the map Is selected and divided into a second plurality of cells each addressable by a second unique identifier, wherein the second unique Identifier has a shorter length, i.e. comprises fewer characters than the first unique Identifier. A location within the first and second map portions covered by the first and second plurality of cells is capable of being identified using both of the first and second identifiers, although as will be appreciated only one of the identifiers will typically be used ln practice. The second identifier is typically more convenient In use due to its shorter length, but there may be circumstances in which it may be désirable to use the longer first identifier.

ln some embodiments the second portion is selected based on one or more attributes associated with one or more régions of the map, such as the shape of a landmass or defined

-5borders between countries, régions and the like. By suitable sélection of such attributes, optionally In association with other criteria, such as population density, the frequency of use of the second Identifier can be arranged to be greater than the first Identifier. As will be explained in more detail below, the frequency of use of the second Identifier may be greater, even though the second portion of the map is smaller than the first portion of the map.

Embodiments of the Invention provide Identifiers for géographie locations having a predetermined number of characters. In most embodiments, the characters are alphanumeric characters. However, In some embodiments, the alphanumeric characters may be selected from a limited set, such as a set Induding only letters and numbers, the set of only le tiers and numbers with 1,0 (zéro), I and O removed in order to avoid accidentai confusion, or the set of only letters and numbers with vowels removed. The set of alphanumeric charaders having 1,0 (zéro), I and O removed provide a set of 34 values, whiist the set having vowels removes provides a set of 31 charaders. It Is also envlsaged that other sets of alphanumeric charaders may be used, such as those induding fewer charaders or those also Induding one or more other charaders or symbols. In some embodiments the identifier Is case Insensltive. For consistency identifiera described herein wili be shown In capitals, although lower case or a mixture may be used. Embodiments of the invention will be explained with reference to the set of 31 charaders mentioned above, although it will be realised that this Is exemplary.

In embodiments of the Invention an identifier for a géographie location comprises a predetermined number of charaders divided Into prefix and postfix portions by a predetermined divlder or separator. The identifier may be divided Into equally or unequally slzed portions, as will be shown. In some embodiments, the prefix and postfix portions at most differ In length by a predetermined number of charaders, such as one charader.

Identifiers according to embodiments of the invention are used to uniquely Identify a géographie area of a predetermined size, known as a cell. The cell may be square, although redangular cells may be used In some embodiments. In some embodiments of the Invention the cell has a size of 10m x 10m, although It wiii be realized that other size ceils may be used, such as 20m x 20m or other sizes.

Given an identifier of charader length n with the cell size (or area) of a the respective géographie area A that may be uniquely identified using a set of c charaders is calculated by:

A = ca

-6Thus, for example, based on the use of 31 characters and a cell size of 100m², the following géographie areas for different numbers of characters is shown in the table below.

Characters	Area (km2)
4	92.4
5	2,862.9
6	88,750.4
8	2,751,261.4
9	2,643,962,216.1

In order to make identifiera more easily human distinguishable and conveyable, embodiments of the invention will be described which identifiera are dlvided by a dot although it will be realized that identifiera may be divlded by other symbols, such as a semicolon

Thus a four character identifier according to an embodiment ofthe invention may be US.SK; a five character identifier as AB.CDE; a six character identifier as FGH.I JK, and so on. In some embodiments the prefix Is a minimum of two characters in length. As noted above, in embodiments of the invention, for a géographie area at least some portions of the area are uniquely identifiable by two or more unique identifiera or different lengths.

Figure 11llustrâtes Identifiera associated with a map according to an embodiment of the invention. A country 100 is schematically illustrated. Whiîst a country is referred to with reference to Figure 1 it will be realised that the area of land indicated as 100 could be a state, région, such as the Européen Union, or otherwise demarcated area of land. The exemplary country 100 comprises three areas of significant population, suchascities 111,112,113.

It may be desired to be able to identify locations across an entirety of the country 100. Therefore the entire area of the country 100 may be compared against the table above, or other équivalent table for the respective number of characters used, to détermine the number of characters necessary to form an identifier to identify locations throughout the country 100 with a respective cell size. For example, the Netherlands covers an area of approximately 42,000 km². Therefore It is necessary to use a six character Identifier for the country 100.

Identifiera for the country 100 may be assigned to a single unitary area covering the entire country, such as rectangular area 110 which is sized and located to cover the entire country 100.

However, depending on the shape of the area to be covered, it may be more efficient to asslgn

-7Identifiera across a plurality of smaller areas having a combined maximum area of up to the limit for the chosen number of characters forming the identifier. For example, six figure identifiera may be assigned amongst areas 121,122,123,124 and other corresponding areas shown in Figure 1 but not specifically indicated with reference numerals. These areas 121,122,123,124 are each smaller than the area of the country 100 and may be arranged to tesseilate to cover the entire country 110. However in other embodiments, as will be explained, it may not be necessary to cover the entire country and areas 121,122,123,124 may be located to substantially cover the country 100 according to one or more predetermined criteria. Six figure identifiera are then assigned to cells arranged within the areas 121,122,123,124. The area 110 or areas 121,122, 123,124 are associated with a context identifier for the area of land, i.e. the country 100. The context identifier may be an ISO defined identifier, for example an ISO 3166 country code, although it will be realised that other Identifiera may be used, such as another letter or plurality of lettera, or one or more numbera selected to identify the country in a context table, as will be explained.

It is likely that it will be required to identify some areas of the country 100 more frequently than others. For example, it is more likely that it Is required to identify locations of homes, businesses, etc than rural or relatîvely unpopulated areas. Therefore, some régions or portions of the country 100 are also associated with identifiera of a shorter length than those utilised for area 110 orareas 121,122,123,124. In this example, a five character identifier may be used with a cell size of 100m² to identify locations in one or more area(s) up to 2,862.9 km². Therefore one or more portions ofthe countryareselected to also be identified byafive characteridentifier. Amethod of selecting the portions is explained below. In an exemplary embodiment of the invention the portions are selected according to population density. Thus the most populated areas of the country are covered by one or more areas in which locations are associated with shorter identifiera, such as a five character Identifier, although it will be appreciated that the number of characters is merely illustrative.

Figure 1 shows three areas 131,132,133 In which locations are identified by five character identifiera. The locations of these three areas are selected to correspond to the most highly populated régions in the country, i.e. cities 111,112,113. Whilst three areas are shown it will be realised that there may be n régions, where n Is 1 or more having a total (combined) area of up to

2,862.9 km². For example, each of the areas 131,132,133 may hâve a predetermined size of 100 km² and located to correspond to the most highly populated areas within country 100. Thus up to 28 areas may be allocated to cover the most highly populated areas within country 100.

Still further, one or more areas having a yet shorter identifier may be located overiying country 100 to correspond to the most densely populated régions within the country 100. Figure 1

-8contains an enlarged view of city 113 wherein a portion of the city Is covered by an area 141 In which locations are Identified using a fourcharacter Identifier.

In the above example, locations within each area forming a hlerarchy of areas 121,131,141 are Identified using identifiers having a progresslvely shorter length to the same accuracy, i.e. ali associated with a cell ofthe same size, such as 10m x 10m. However It will be realised that Identifiers of each respective length may Identify locations to a different degree of accuracy, i.e. each length identifier may be associated with cells of a different size. For example the six character identifier may be assodated with a cell size of 50m x 50m, the five character Identifiers may be associated with a cell size of 20m x 20m and the four character Identifiers may be associated with a cell size of 10m x 10m. In these embodiments a greater précision of location Identification can be achieved with shorter identifiers. Furthermore, shorter Identifiers are also more easily to remember and convey between persons, either In writing or aurally.

Figure 2 Illustrâtes a property of the Identifiers which enables easier récognition of locations and usage. Figure 2 illustrâtes an arrangement of a six character Identifier. A first région Is identified by a selected first character of the Identifier, such as character G**.*** where * is a wildcard character. A second smaller région within the first région 1s Identified by the Inclusion of a first, next least significant, character of the identifier, such as G0‘.***. Similarly by the inclusion of a further character, such as G02.3**, a still smaller area can be located. Thus for persons using the identifiers according to embodiments of the Invention an area may be referred to at lower précision using only some ofthe characters forming the identifier, such as the G20.2 area which Is only part of the six character Identifier.

It will be appreciated that for some locations within country 100, such as a location within the area 141, i.e. within city 113, locations may be Identified by, not only the four character identifier defined within the area 141, but also by the five character Identifier defined by area 132, and also by six character Identifier associated with the one or more surrounding areas. In embodiments where ail length identifiers use the same size cells, the précision of using ail length identifiers Is the same.

A method 300 of asslgning identifiers to géographie locations will now be described with reference to Figure 3.

Two variables are used in the method 300 shown in Figure 3. A first variable y Is used to track portion(s) of the map being selected. The first variable is initialised to y = 1 at the start of the method 300. A second variable x Is used to track a length of the identifier for the y*” area. In the embodiment described x is initialised to 6, this being the number of characters chosen or necessary to identify locations In the y⁰' area, although It will be realised that other Initialisation values may be

-9used. A cell size may also be selected prior to the method beginning, or a predetermined cell size may be selected prior to the method, such as the cell size of 10m x 10m referred to above. The variable x may only be Initialised in step 310 once the first portion of the map has been selected. ln this way, the length x ln characters of the first identifier may be selected to uniquely identify locations throughout the area of the first map portion, given the cell size.

The method starts with a map of a géographie area. The map may be stored as digital map data in a memory or other storage device of a computing device; the digital map data typically being a digital représentation of the géographie area. The method 300 may be performed by a processor of the computing device operating according to a computer program arranged, when 10 executed by the processor, to perform the method 300. The computer program may be tangibly stored on a computer readable medium. The map may be for the entire worid, or a smaller portion thereof such as a région, I.e. a continent, a country or a state. Other portions are also envisaged.

In step 310 one or more first (y ” 1) portions of the map are selected. The map may represent an entire country, although the map may also relate to part of a country, such as a state, 15 e.g. a US state. For explanation It will be assumed that the map relates to the country 100 shown ln Figure 1. The first portion of the map may be selected by defining a rectangle around the entire territory or country 100, ln which case the first portion is a unitary area such as area 110 shown In Figure 1. However in other embodiments the one or more portions of the map may be selected according to one or more predetermined criteria. The one or more criteria may be chosen such that 20 the selected portions hâve the hlghest likelihood of usage, ln one embodiment, the portions are selected according to population density. However it will be realised that other criteria may be chosen, such as building density, road layout, etc, so as to Increase a likelihood of the portions covering areas where Identification of locations is useful. ln the example embodiment, the portions are arranged based on population density. The population density may be determined based upon 25 a density of house numbers, point addresses or in other suitable manners. ln an Illustrative example, the country 100 will be described as the Netheriands around which a rectangle ls defined around the complété territory within which locations are to be identified using six character identifie rs.

In step 320 cells are assigned to cover the first map portion selected ln step 320. The cells 30 may be distributed over a single unitary area, such as area 110 or divided amongst a plurality of areas, such as areas 121,122,123,124.

The location and identification of the cells may be stored în a data storage structure, such as a database for later retrieval and use. The database may store one or more context tables which may be used by a computing device, such as a navigation device, to détermine géographie 35 locations based on received identifiers. Each context table may comprise a context identifier

-10associated with a géographie région, such as a country or state. The context identifier may be a letter or number Identifying the région, such as an ISO code for the country. Associated with the context Identifier In the table Is Identification Information relating to a first plurality of cells for the géographie région. The first plurality of cells are each identified by an Identifier of a first length, such as six characters, although it wiii be realised that other lengths may be used depending, at least partly, on the area of the région. Also stored In the context table is identification information relating to a second plurality of cells, wherein each cell Is associated with a unique Identifier of a second length, shorter than the first length. For example the second length may be five characters. The second plurality of cells uniquely Identifies locations within a sub-region of the géographie région Identified by Identlfiers ofthe first length. That is, wherein géographie locations within the second plurality of cells are uniquely identified by identifiera of both the first and second lengths. As wiii be explalned, the context table may be used by a navigation device to détermine géographie locations from received identifiera, such that routes may be calculated between first and second locations Identified by first and second Identifiera, which may be of different lengths.

In step 330 the x character identifier is asslgned to a context. A context Is an identifier which associâtes the identifier with the first map portion, such that lower level (shorter) identifiera may also be associated with the first map portion, as wiii be explained. Where the first map portion is a country, the x character identifier is associated with a context which identifies the country. In some embodiments, the context is Identified by an ISO country code which for the Nethertands Is NL (2 digit) or NLD (3 digit). However the Identifier may be associated with other types of code for a géographie région such as EP for Europe or TX for the US state of Texas, as examples. In still further embodiments the identifier may be any selected letter or number chosen to identify the context.

in step 340 y Is Incremented to indicate that one or more second portions (for the first itération of step 340) of the map are to be selected and x is decremented to utilise a shorter Identifier for the second portions. Whilst In the Illustrative example x is decremented by 1, this Is not essential and x may be decremented by more than 1.

In step 350 the one or more second portions (for the first itération of step 150) ofthe map are selected. The maximum number and size of the second portions may be predetermined according to the length of the Identifier. For example, given that a 5 character identifier may Identify up to 2,862.9 km’ for a cell size of 100 m^z up to 28 second portions of the map may be selected each having a size of 100 km². Other sizes may be chosen and the maximum number of portions varied accordingly. Step 350 may comprise a sub-step of determining a population density of locations, based upon which the portions of the map are seiected. The population density may be

-11 calculated based upon house numbers, point addresses, lists of dties and associated populations, etc.

Thus In an exemplary embodiment of step 350 up to 28 second portions of the map are selected each having a size of up to 100 km². Altematively, this step may be considered as locating up to 28 régions with respect to the map data. For the Netherlands a 5 character identifier and cell size of 100 m² is expected to cover approximately one quarter of the population or around 4 million people.

Figure 4 illustrâtes, as an example, The Netherlands as a country 400 having a plurality of second portions 410,420 (oniy two of which are identified with reference numerals) selected based upon population density.

in step 360 cells are assigned according to the identifier of x characters In length, such as a five character AB.XYZ Identifier, amongst the second portions of the map such that ali of the second portions may be identified according to the cell size. The location and identifier associated with each cali may be stored In the database.

In step 370 the ceils are associated with a context. The context for the second portions may also be the country code or other identifier chosen for the context. However, the context for the second portions may additionally or altematively be another feature of the map data such as a city name. For exampie if a second portion of the map covers Amsterdam then the context for that second portion may be the city name.

The régions may be associated by storage In a database associated with the context identifier.

in step 380 It is determined whether the method 300 has finished. Termination of the method may be performed when a minimum size identifier has been reach, such as x = 4, i.e. a shortest identifier of four characters, aithough other predetermined values may be used.

If the method has not finished then it retums to step 340 where, in the second Itération y is Incremented to select one or more third portions of the map to identify with the decremented Identifier length of x = 4.

In the next Itération of step 350 the one or more third portions of the map are selected according to predetermined criteria. Aithough the same criteria may be used as in the previous itération of step 350 It is envisaged that, in some embodiments, one or more alternative criteria may be used. in the exemplary embodiment the third portions may be between one or five portions of the map of 18.4 km² thus having a total area of iess than 92.4 km². It will be realised that other size areas may be utilised. The third portions are selected to cover the most populated réglons of the

-12map. For tha Netheriands tha five third portions are expected to cover around 1.5 million people or 10% ofthe population.

Figure 5 illustrâtes a third portion 510 ofthe exemplary map ofthe Netheriands selected in step 350. The portion 510 corresponds to the city of Amsterdam which is selected due to its relatively high population density.

In step 370 tha third portions are assigned to a context, such as stored in the database associated with the ISO country code NL, respective city name or other context identifier.

The method 300 may be appiied to détermina Identifiera for ali countrîes in tha world. Currently there are believed to be 196 countrîes and 53 overseas/autonomous entitles. Firstly, an area is defined around each country in step 310. For countrîes larger than 2.7 million km² (corresponding to an eight figure identifier) such as the USA and India states or other sub-regions of the country may be used as the first portion of the map. Figure 6 illustrâtes a portion of the earth in relation to first portions selected in step 310. In following répétitions of step 350 second and third portions of the map are selected which may correspond to the most populous areas within those countrîes or states.

Figure 7 is an iilustrative représentation of electronic components of a navigation device 700 according to a preferred embodiment ofthe présent Invention, In block component format. It should be noted that the biock diagram of the navigation device 700 is not inclusive of ali components of the navigation device, but Is only représentative of many example components.

The navigation device 700 is located within a housing (not shown). The housing includes a processor 710 connected to an input device 720 and a display screen 740. The input device 720 can Include a keyboard device, voice input device, touch panel and/or any other known input device utilised to Input information; and the display screen 740 can Include any type of display screen such as an LCD display, for example. In a particularly prefened arrangement the input device 720 and display screen 740 are integrated into an integrated Input and display device, Including a touchpad or touchscreen Input so that a user need only touch a portion of the display screen 740 to select one of a plurality of display choices or to activate one of a plurality of virtual buttons.

The navigation device may indude an output device 760, for example an audible output device (e.g. a loudspeaker). As output device 760 can produce audible information for a user of the navigation device 700, it is should equaily be understood that input device 740 can Include a microphone and software for receiving input voice commands as well.

in the navigation device 700, processor 710 Is operatively connected to and set to receive input information from input device 720 via a connection 725, and operatively connected to at least one of display screen 740 and output device 760, via output connections 745, to output information

-13thereto. Further, the processor 710 ls operably coupled to a memory resource 730 via connection 735 and ls further adapted to recelve/send Information from/to input/output (I/O) ports 770 via connection 775, wherein the I/O port 770 is connectibie to an I/O device 780 extemal to the navigation device 700. The memory resource 730 comprises, for example, a volatile memory, such as a Random Access Memory (RAM) and a non-volatiie memory, for example a digital memory, such as a flash memory. The extemal I/O device 780 may Include, but is not limited to an extemal listening device such as an earplece for example. The connection to I/O device 780 can further be a wired or wireless connection to any other extemal device such as a car stéréo unit for hands-free operation and/or for voice activated operation for example, for connection to an ear piece or head phones, and/or for connection to a mobile phone for example, wherein the mobile phone connection may be used to establish a data connection between the navigation device 700 and the internet or any other network for example, and/or to establish a connection to a server via the Internet or some other network for exampie.

Figure 7 further iilustrates an operative connection between the processor 710 and an antenna/receiver 750 via connection 755, wherein the antenna/receiver 750 can be a GPS antenna/receiverfor example. It will be understood that the antenna and receiver designated by référencé numéral 750 are combined schematically for Illustration, but that the antenna and receiver may be separately located components, and that the antenna may be a GPS patch antenna or helical antenna for example.

Further, it will be understood by one of ordinary skill in the art that the electronic components shown in Figure 7 are powered by power sources (not shown) in a conventional manner. As will be understood by one of ordinary skill in the art, different configurations of the components shown in Figure 7 are considered to be within the scope of the présent application. For example, the components shown In Figure 7 may be In communication with one another via wired and/or wireless connections and the like. Thus, the scope of the navigation device 700 of the présent application includes a portable or handheld navigation device 700.

In addition, the portable or handheld navigation device 700 of Figure 7 can be connected or docked In a known manner to a vehicle such as a bicycle, a motorbike, a car or a boat for example. Such a navigation device 700 is then removable from the docked location for portable or handheld navigation use.

Figure 8 shows a software stack that may be used in a preferred embodiment of the mobile navigation device 700. The stack comprises an OS kernel 800. This may Include display drivera, keypad drivera, caméra drivera, power management, audio drivera, etc. The stack also comprises libraries 804, e.g. Including graphies libraries, runtime libraries, etc. The stack aiso comprises an application framework 806, which includes a mapcode module 810 and may also include, for

-14example, a window manager, resource manger notification manger, a telephony manager, etc. The stack also comprises one or more applications 802, I.e. to provide navigation functionalîty.

The mapcode module 810 provides one or more function associated with the Identifiers discussed above. The mapcode module opérâtes ln conjunction with a store comprising one or more context tables as referred to above.

ln one embodiment the mapcode module provides a DecodeMapcode function which given an identifier according to an embodiment of the Invention détermines the géographie location corresponding to the identifier. The DecodeMapcode function may retum coordinates in a predetermlned coordinate System of a centre of the respective cell, such as ln WGS84 format. The mapcode module 810 may be arranged to détermine the géographie location corresponding to the Identifier and context Information. The context information may be the ISO country code associated with the identifier, such as NL, or may be a city name such as Amsterdam. The context Information allows the mapcode module to distinguish an identifier of a particular length relating to a first country from an Identifier of the same length relating to a second country. The context information may be Inferred by mapcode module 810 from the current location of the navigation device 700. For example, if the navigation device 700 détermines that its current location ls The Netheriands then the mapcode module may use NL as the default context Information, unless a user enters spécifie context Information.

Other fonctions which may be provided by embodiments of the mapcode module 810 are GetPossibleMapcode which retums a iîst or array of possible Identifiers given a portion of an identifier entered by a user and the context Information. The possible Identifiers may be determined based on the portion of the Identifier and the Identifiers matching that portion in the database.

Similarly, a function ’NrOfPossibleMapcodes* may retum a value Indicative of the number of Identifiers corresponding to the portion of the identifier entered by the user.

The mapcode module 810 may ln some embodiments also provide a function EncodeMapcode* which given location Information, such as WGS84 coordinates, and context Information may retum one or more identifiers according to an embodiment associated with that location information, it will be recalled that a plurality of Identifiers may be associated with some locations.

The mapcode module 810 may détermine identifiers corresponding to géographie locations, locations corresponding to Identifiers and possible identifiers from the portion of an Identifier provided by a user by accessing the data storage structure, such as the context table database, storing Identifier and context Information. The database may either be stored locally to the

-15navigation device 700 such as in memory 430 or may be remotely accessed by the navigation device 700 such as via a server and data connection to the navigation device 700.

It will be appreciated that embodiments of the présent Invention provide a system for identifying géographie locations, wherein some locations may be identified by multiple unique Identifiera of different lengths. Advantageously this aliows a shorter identifier to be used to more convenlently identify a location. By allocating cells identified with shorter Identifiers to locations which are more likely to be desired to be Identified, the average length of Identifier In use can be reduced. Furthermore, using embodiments of the invention there are reduced limitations on the number of locations that may be Identified with shorter identifiers te. more than one location may be Identified with an identifier of a chosen length.

Embodiments of the présent invention can be realised In the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or In the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the présent invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a machine readable storage storing such a program. Still further, embodiments of the présent Invention may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same.

Ail of the features disclosed In this spécification (including any accompanying claims, abstract and drawings), and/or al! of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed In this spécification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, équivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed Is one example only of a generic sériés of équivalent or similar features.

The Invention is not restricted to the details of any foregolng embodiments. Moreover, the claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

Claims (20)

1. A computer-implemented method for asslgnlng identifiers to géographie locations within digital map data, comprising:

selecting a région within the map data;

divlding the région Into a first plurality of cells each uniquely addressabie by an identifier of a first length;

selecting a portion of the région; and divlding the portion into a second plurality of cells each uniquely addressabie by an Identifier of a second length, wherein the second length Is shorter length than the first length and a géographie location within the portion of the région may be uniquely identified by an Identifier of the first length and an Identifier of the second length.

2. The method of claim 1, wherein the portion of the région is selected based on one or more attributes ofthe map data.

3. The method of claim 2, wherein one or both of the région and the portion of the région are selected based upon one or more criteria and the attributes of the map data.

4. The method of claim 3, wherein the criteria are indicative of a population density associated with the digital map data.

5. The method of any preceding claim, wherein the région corresponds to a région demarcated In the map data.

6. The method of any preceding daim, comprising selecting one or more further portions of the région, and dividing the one or more further portions into further pluraiities of cells each uniquely addressabie by an Identifier of successively short length.

7. The method of daim 6, wherein a géographie location In each further portion of the région is identifiable by a plurality of identifiers or different lengths.

8. The method of any preceding claim, wherein the région and the one or more portions are divided into substantially equally sized cells.

9. The method of any preceding claim, wherein the identifier comprises prefix and postfix portions divided by a separator.

10. The method of any preceding claim, wherein the identifier is formed from alphanumeric characters.

11. A context table for identifying géographie locations, comprising:

a context identifier associated with a géographie région;

information Identifying a location of a firetly plurality of celis dividing at least a part of the géographie région, each ceii being associated with a unique Identifier of a first length; and

Information Identifying a location of a second plurality of ceils dividing one portions of the géographie région, each cell being associated with a unique identifier of a second length, wherein géographie locations within the second plurality of cells are uniquely identified by identifiera of the first and second lengths.

12. The context table of claim 11, comprising one or more further pluralities of cells dividing portions of the géographie région, each ceil in each respective plurality of cells being associated with a unique identifier of successively decreaslng length.

13. The context table of claim 11 or 12, wherein the first and second pluralitîes of cells are associated with the context identifier.

14. The context table of claim 13, wherein the second plurality of cells is associated with one or more further context Identifiera.

15. The context table of any of claims 11 to 14, comprising size information indicating a size of each cell In the first and second plurality of cells.

16. The context table of any of claims 11 to 15 generated using the method of any of claims 1 to 10.

17. A computing device having a store comprising a context table according to any of claims 11 to16.

18. A navigation device, comprising:

a display screen for providing navigation information to a user; and a processor communicably coupled to a data store comprising a context table according to any of claims 11 to 16, wherein the processor is arranged to receive, from a user, at least one identifier, and to détermine at least one géographie location corresponding to the respective Identifier from the context table.

19. The navigation device of claim 18, wherein the at least one Identifier received from the user is représentative of a desired destination, and the processor is arranged to détermine a route to the géographie location Identified by the received identifier.

20. The navigation device of claim 18 or 19, wherein the processor is arranged to receive a context identifier from the user, wherein the context identifier Is indicative of a géographie région, and wherein the processor is arranged to détermine the at least one géographie location using the context table based on the received context identifier.