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This page is an archive. LocaPoint(this version) is Obsolate and moved to "LP Address" for better solution.
For more detail, please refer LP Address (LocaPoint2) Web site


LocaPoint Specification

Version 2.0.0    2,July,2006

1. Format

LocaPoint has following format and total 15 letters in length.

AAN.AAN.AAN.AAN

"A": represents one of alphabet, A-Z
"N": represents one of number, 0-9
".": period as delimiter

2. Chunks

"AAN" block is called "Chunk".
From left to right, each chunk has following names and meanings.
  • First Chunk: Latitude element of Area Code
  • Second Chunk: Longitude element of Area Code
  • Third Chunk: Latitide element of Local Code
  • Fourth Chunk: Longitude element of Local Code

3. Possible Value

Each chunk can have a value from "AA0" to "ZZ9", 6760 ( =26 * 26* 10) patterns total.

Incrementing:
Chunk starts from "AA0", then increment as:
"AA1", "AA2", "AA3",....

Number digit increments as 0,1, 2 ...8, 9, and Alphabet digit increments as A, B, C, .....Y, Z.

Carry Over:
Carry over happens when increment on "9" or "Z" as:

..., "AA8", "AA9", "AB0", "AB1", "AB2", ...

..., "AZ8", "AZ9", "BA0", "BA1", "BA2", ...

4. Area Code

AAN.AAN.AAN.AAN
First and Second Chunk constructs Area Code.
Both latitude and longitude for whole world are divided into 6760 areas, then name them from "AA0" to "ZZ9" in east or north direction.

5. Local Code

AAN.AAN.AAN.AAN
Third and Forth Chunk constructs Local Code.
Local Code points a location within Area.
Both latitude and longitude within each Area are divided into 6760 areas correspondingly, then name them from "AA0" to "ZZ9" in east or north direction.
 

6. Encode/Decode Logic

LocaPoint has a linear relationships with Latitude and Longitude in WGS84 datum.
To be precise, LocaPoint corresponds latitude and longitude of South-West corner of a small area that is determined by LocaPoint.

6-1. Latitude

Jointing First and Third Chunk constructs Latitude Code, which is used for encoding/decoding.
AAN.AAN.AAN.AAN
Latitude Code from "AA0 AA0" to "ZZ9 ZZ9" corresponds 0 to 45697599 in decimal integer, and linearly corresponds latitude -90 degree to +89.99999 degree.

Calculation:
 (Latitude Code in decimal integer) = Roundoff ((Latitude + 90) /180 * 45697600)

Minimum Value Mid value Maximum Value
Latitude -90.0(South) 0(equator) +89.999999(North)
Latitude Code AA0.***.AA0.*** NA0.***.AA0.*** ZZ9.***.ZZ9.***
Latitude Code in decimal 0 22848800 45697599

- sample program code here -
 

6-2. Longitude

Jointing Second and Forth Chunk constructs Longitude Code, which is used for encoding/decoding.
AAN
.AAN.AAN.AAN

Longitude Code from "AA0AA0" to "ZZ9ZZ9" corresponds 0 to 45697599 in decimal integer, and linearly corresponds latitude -180 degree to +179.99999 degree.

Calculation
 (Longitude Code in decimal integer) = Roundoff (Longitude + 180) /360 * 45697600)
 

Minimum Value Mid value Maximum Value
Longitude -180(West) 0(Greenwich) +179.999999(East)
Longitude Code ***.AA0.***.AA0 ***.NA0.***.AA0 ***.ZZ9.***.ZZ9
Londitude Code in decimal 0 22848800 45697599

- sample program code here -