×

Method and apparatus for backtracking a path

DC
  • US 6,459,987 B1
  • Filed: 11/15/1996
  • Issued: 10/01/2002
  • Est. Priority Date: 11/15/1996
  • Status: Expired due to Term
First Claim
Patent Images

1. A method for generating a backtrack from a plurality of data points which have been stored in a memory of a Global Positioning System, said data points having a first, last and intermediate data points corresponding to geographic positions, the method comprising the steps of:

  • initializing a counter C to a value of 1, said counter C corresponding to a memory location on a memory stack;

    storing said last data point in said memory stack at a first memory location;

    assigning said last data point to a variable E;

    initializing a stack counter N to a value of 2;

    assigning said first data point to a variable B;

    comparing said counter C to zero;

    conducting the following steps if said counter C is greater than zero;

    computing a straight line from said variable B to said variable E;

    computing a shortest distance for each of said intermediate data points from said straight line, thereby having a plurality of shortest distances corresponding in a one to one relationship to said intermediate data points;

    determining the longest of each of said shortest distances and assigning said intermediate data point corresponding to said longest distance to a variable L and assigning said longest distance to a variable D;

    comparing said variable D to a threshold value;

    increasing the value of counter N by one, storing said variable L in said memory stack at memory location S(C), assigning the value of variable L to variable E, and returning to said comparing said counter C to zero step;

    if D is greater than said threshold value;

    decreasing the value of counter C by one, assigning the value of variable E to variable B and assigning the value of stack memory location S(c−

    1) to variable E, and returning to said comparing said counter C to zero step;

    if D is less than or equal to said threshold value;

    conducting the following steps if variable C is less than or equal to zero;

    comparing N to a predetermined memory limit;

    increasing said threshold value by a predetermined value, and returning to initializing a counter C step;

    if N is greater than said memory limit; and

    navigating to said first position utilizing said positions stored in said stack as way-points for said global positioning system.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×