Geographical location indexing
A geographical location index comprising a plurality of layers of geographical information concerning a geographical area, each layer comprising a division of the geographical area into a plurality of discrete zones which each have a zone identifier and associated geographical co-ordinates of one or more geographical locations contained within that zone.
1 . A computer-readable medium having stored thereon a geographical location index comprising a plurality of layers of geographical information concerning a geographical area, each layer comprising a division of the geographical area into a plurality of discrete zones which each have a zone identifier and associated geographical co-ordinates of one or more geographical locations contained within that zone.
2 . An index according to claim 1 , wherein each zone has a finite number of neighboring zones in the same layer.
3 . An index according to claim 1 , wherein each layer defines a different set of zones.
4 . An index according to claim 3 , wherein the zones in one layer represent a predetermined geographical area.
5 . An index according to claim 4 , wherein the predefined geographical area in one layer is a country, in another layer is a state, in another layer is a county, in another layer is a postcode/zip code and in another layer is a building.
6 . An index according to claim 5 , wherein there is a hierarchy of layers having respective zones of diminishing area so that a top layer provides low resolution division of the geographical area a bottom layer provides high resolution division of the geographical area.
7 . An index according to claim 1 , wherein for a particular layer, a record of a subject zone contains a zone identifier for the subject zone, the zone identifiers of zones neighboring the subject zone, the or each zone identifier of a zone in another layer containing the subject zone and the zone identifiers of all zones contained within the subject zone.
8 . An index according to claim 1 , wherein the zones of one layer do not overlap any other zones of the same layer.
9 . An index according to claim 1 , wherein a zone of one layer overlaps one or more zones of another layer.
10 . An index according to claim 1 , wherein the associated geographical co-ordinates comprise the longitude and latitude or x,y co-ordinates of at least one geographical location in a subject zone.
11 . An index according to claim 1 , wherein each zone is a polygonal area.
12 . A database incorporating an index according to claim 1 .
13 . A method of indexing data relating to geographical locations comprising:
providing a plurality of layers of geographical information concerning a geographical area, each layer comprising a division of the geographical area into a plurality of discrete zones, each of which has a zone identifier and associated geographical co-ordinates each of which co-ordinates defines a geographical location; and associating for each layer a geographical location with those zones containing the geographical location such that a geographical hierarchy is provided for each geographical location.
14 . A method of utilizing a geographical location index comprising a plurality of layers of geographical information concerning a geographical area, each layer comprising a division of the geographical area into a plurality of discrete zones which each have a zone identifier and associated geographical co-ordinates of one or more geographical locations contained within that zone, the method comprising searching the index for a target geographical location and determining therefrom one or more nearby geographical locations or data concerning the nearby geographical locations.
15 . A method of analyzing the content of a body of information with reference to a geographical location index comprising a plurality of layers of geographical information concerning a geographical area, each layer comprising a division of the geographical area into a plurality of discrete zones which each have a zone identifier and associated geographical co-ordinates of one or more geographical locations contained within that zone, to determine whether geographical locations named in the body of information fall into a predetermined set of zones.
16 . A method according to claim 15 , wherein there are a plurality of bodies of information which are ranked with respect to one another, the method further comprising confirming, lowering or raising the ranking of one of the bodies of information in dependence on an extent to which geographical locations named in the body of information fall into the predetermined set of zones.