Importance

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Abstract

Methods for determining the present location coordinates of a user moving in a two-dimensional or three-dimensional space, with reference to an old map that may be inaccurate. Location coordinates of two or three non-collinear landmarks in two dimensions, or coordinates of three or four non-coplanar landmarks in three-dimensions, are indicated on the old map. Corresponding location coordinates are also estimated using a location determination (LD) system, such as GPS, GLONASS, Loran, Tacan, Decca, Omega, VOR, DME, JTIDS, PLRS or an FM subcarrier system. Location coordinates for two or more physical landmarks can be used to determine coordinates for a landmark representative. The user's location coordinates are also determined or provided using the LD system. A distance or separation vector from the user location to landmark number i (i=1, . . . , N; N=2,3) is computed in the LD system. Two or more locations are computed on the old map for which the estimated distance (or estimated vector) from landmark number i to the computed location on the old map is also equal to the computed distance (or computed vector), and one of these computed locations is designated as a user location on the old map. Several metrics are developed to measure the relative acceptability of an old map user location, as determined above.

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First Claim