Navigation trajectory matching

1. A computer-implemented method comprising

receiving first data from an inertial tracking device worn by a first person, the first data defining a first tracked path traversed by the first person;

receiving second data from an inertial tracking device worn by a second person, the second data defining a second tracked path traversed by the second person;

identifying a first location on the first tracked path that substantially matches a second location on the second tracked path;

calculating a correction parameter based on a separation between the first location and the matching second location;

adjusting one or both of said first or second tracked path by applying the correction parameter to bring the first and second tracked paths into closer alignment; and

performing at least one action from the group of (a) displaying the more closely aligned first and second tracked paths on a visual display; and (b) providing automated instructions to the second person based on the more closely aligned first and second tracked paths.

2. The method of claim 1 in which the first and second locations are at successive footsteps of the first or the second person along the first or second tracked path, respectively.

3. The method of claim 1 in which the first and second tracked paths are determined based on identification of one or more known reference points.

4. The method of claim 1 further comprising, receiving third data from said second inertial tracking device, said third data defining an extension of said second path, and applying said correction parameter to locations on said extension to realign said extension.

5. The method of claim 1 , wherein the correction parameter is applied to an additional location on said first path.

6. The method of claim 1 , wherein the correction parameter is applied to an additional location on said second path.

7. The method of claim 1 , wherein applying the correction parameter comprises adjusting a location other than said first or said second location.

8. The method of claim 1 , comprising displaying the more closely aligned first and second tracked paths on a visual display.

9. The method of claim 1 , comprising providing automated instructions to the second person based on the more closely aligned first and second tracked paths.

10. A computer-implemented method comprising

receiving first data from an inertial tracking device worn by a first person, the first data approximating a set of first locations along a path that was traversed by the first person;

receiving second data from an inertial tracking device worn by a second person, the second data approximating a set of second locations being traversed by the second person;

estimating a correction parameter based on a separation between a given second location and a corresponding first location, wherein the corresponding first location is determined by correlating features associated with the first and second locations;

estimating a current location of the second person with respect to the path based on the correction parameter; and

performing at least one action from the group of (a) displaying said more closely aligned first and second tracked paths on a visual display; and (b) providing automated instructions to said second person based on said more closely aligned first and second tracked paths.

11. The method of claim 10 in which the first and second locations are at successive footsteps of the first or the second person along the first or second tracked path, respectively.

12. The method of claim 10 in which the first and second locations are determined based on identification of one or more known reference points.

13. The method of claim 10 further comprising, receiving third data from said second inertial tracking device, said third data including additional locations in the set of second locations, and applying said correction parameter to at least one of the additional locations to align the at least one additional location to the path.

14. The method of claim 10 , comprising displaying the more closely aligned first and second tracked paths on a visual display.

15. The method of claim 10 , comprising providing automated instructions to the second person based on the more closely aligned first and second tracked paths.

16. A computer program product comprising a computer readable storage device encoded instructions, which when executed, causes one or more processors to perform operations comprising:

receiving first data from an inertial tracking device worn by a first person, the first data defining a first tracked path traversed by said first person;

receiving second data from an inertial tracking device worn by a second person, the second data defining a second tracked path traversed by said second person;

identifying a first location on said first tracked path that substantially matches a second location on said second tracked path;

calculating a correction parameter based on a separation between the first location and the matching second location;

adjusting one or both of said first or second tracked path by applying the correction parameter to bring said first and said second tracked paths into closer alignment; and

performing at least one action from the group of (a) displaying said more closely aligned first and second tracked paths on a visual display; and (b) providing automated instructions to said second person based on said more closely aligned first and second tracked paths.

17. The computer program product of claim 16 , wherein the operations include receiving third data from the second inertial tracking device, the third data defining an extension of the second path, and applying the correction parameter to locations on the extension to realign the extension.

18. The computer program product of claim 16 , wherein the operations include displaying the more closely aligned first and second tracked paths on a visual display.

19. The computer program product of claim 16 , wherein the operations include providing automated instructions to the second person based on the more closely aligned first and second tracked paths.

20. A computer program product comprising a computer readable storage device encoded instructions, which when executed, causes one or more processors to perform operations comprising:

receiving first data from an inertial tracking device worn by a first person, the first data approximating a set of first locations along a path that was traversed by the first person;

receiving second data from an inertial tracking device worn by a second person, the second data approximating a set of second locations being traversed by the second person;

estimating a correction parameter based on a separation between a given second location and a corresponding first location, wherein the corresponding first location is determined by correlating features associated with the first and second locations;

estimating a current location of the second person with respect to the path based on the correction parameter; and

performing at least one action from the group of (a) displaying said more closely aligned first and second tracked paths on a visual display; and (b) providing automated instructions to said second person based on said more closely aligned first and second tracked paths.

21. The computer program product of claim 20 , wherein the operations include receiving third data from said second inertial tracking device, said third data including additional locations in the set of second locations, and applying said correction parameter to at least one of the additional locations to align the at least one additional location to the path.

22. The computer program product of claim 20 , wherein the operations include displaying the more closely aligned first and second tracked paths on a visual display.

23. The computer program product of claim 20 , wherein the operations include providing automated instructions to the second person based on the more closely aligned first and second tracked paths.