Compact text encoding of latitude/longitude coordinates

• US 20050023524A1
• Filed: 07/31/2003
• Published: 02/03/2005
• Est. Priority Date: 07/31/2003
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Beatty, Bryan Kendall
• Granted Patent: US 7,302,343 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• CPC Class Codes: G06F 16/9566 URL specific, e.g. using aliases, detecting broken or misspelled links
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching

Abstract

Methods are disclosed for encoding latitude/longitude coordinates within a URL in a relatively compact form. The method includes converting latitude and longitude coordinates from floating-point numbers to non-negative integers. A set of base-N string representations are generated for the integers (N represents the number of characters in an implementation-defined character set being utilized). The latitude string and longitude string are then concatenated to yield a single output string. The output string is utilized as a geographic indicator with a URL.

Claims

1. A computer implemented method of reducing the number of characters contained in a geographically-oriented string that includes a floating-point coordinate value, the method comprising:

converting the floating-point coordinate value to an integer value; and

converting the integer value to a base-N string, wherein N represents the number of characters in an implementation-defined character set; and

using the base-N string as part of the geographically-oriented string.

2. The method of claim 1, wherein the geographically-oriented string is a geographically-oriented Uniform Resource Locator associated with a web page.

3. The method of claim 2, wherein converting a floating-point coordinate value to an integer value comprises converting a floating-point representation of a latitude or longitude coordinate to an integer value.

4. The method of claim 2, wherein converting a floating-point coordinate value to an integer value comprises applying a mapping algorithm that preserves a desired level of accuracy.

5. The method of claim 4, wherein applying a mapping algorithm comprises applying a mapping algorithm based at least in part on the circumference of the earth.

6. The method of claim 5, wherein applying a mapping algorithm further comprises applying a mapping algorithm based at least in part on a desired error level in describing a position on the earth.

7. The method of claim 2, further comprising:

converting a second floating-point coordinate value to a second integer value;

converting the second integer value to a second base-N string, wherein N represents the number of characters in an implementation-defined character set;

concatenating the base-N string and the second base-N string to form a concatenated string; and

using the concatenated string as part of a Uniform Resource Locator.

8. A computer implemented method of reducing the number of characters required to represent coordinates within a geographically-oriented string, the method comprising:

selecting a character set having a predetermined number of characters;

selecting a maximum level of allowable error;

calculating, based at least in part on the predetermined number of characters and the maximum level of allowable error, a number of character spaces required to represent a coordinate;

deriving a reduced character coordinate string representation of a coordinate based, at least in part, on the predetermined number of characters, the allowable error, and the number of character spaces; and

placing the reduced character coordinate string representation of the coordinate within the geographically-oriented string.

9. The method of claim 8, wherein the geographically-oriented string is a geographically-oriented Uniform Resource Locator.

10. The method of claim 8, wherein deriving the reduced character coordinate string representation comprises determining an integer mapping range.

11. The method of claim 10, wherein determining an integer mapping range comprises determining an integer mapping range based at least in part on the number of character spaces, and based at least in part on the predetermined number of characters.

12. The method of claim 10, wherein deriving a reduced character coordinate string representation comprises:

converting a floating point coordinate to an integer value based at least in part on the size of the integer mapping range.

13. The method of claim 12, wherein converting a floating point coordinate comprises converting a latitude coordinate.

14. The method of claim 12, wherein converting a floating point coordinate comprises converting a longitude coordinate.

15. The method of claim 12, wherein deriving a reduced character coordinate string representation further comprises:

converting the integer value to a base-N string, wherein N represents the predetermined number of characters.

16. The method of claim 8, wherein deriving a reduced character coordinate string representation further comprises determining a latitude base-N string and a longitude base-N string.

17. The method of claim 16, further comprising concatenating the latitude base-N string and the longitude base-N string to derive a concatenated coordinate string.

18. The method of claim 17, wherein placing the reduced character coordinate string representation within the geographically-oriented string comprises placing the concatenated coordinate string within the geographically-oriented string.

19. A method of reducing the number of characters associated with a set of latitude and longitude coordinates, the method comprising:

converting a floating-point latitude value to a latitude integer value; and

converting the latitude integer value to a first base-N string, wherein N represents the number of characters in an implementation-defined character set;

converting a floating-point longitude value to a longitude integer value; and

converting the longitude integer value to a second base-N string, wherein N represents the number of characters in an implementation-defined character set.

20. The method of claim 19, further comprising concatenating the first and second base-N strings to form a concatenated string.

21. The method of claim 19, wherein converting a floating-point latitude value to a latitude integer value comprises applying a mapping algorithm that is based at least in part on a desired level of accuracy.