GeoLocationEncoding

Encoding Decoding of Geo Location for IOT network for sharing compacted-point-locations in M2M Transections.

Storing Latitude & Longitude in database occupy 32 bits each means total 64 bits. but while transmitting coordinates over http with content-type text/plain or text/html, all digits, signs, floating points & seprater are treated as text-charecter, which occupy 8 bits per charecter means with current 6-decimal-precision it moccupies 22 charecters max, equivalent to 176 bits. Hence, Here tried to compress Geo coordinate from base-10 to base36/62.

Base-62 Comperession

1. max 12 charectets compression from 22 charecters hence 96 bits occupied.
2. It is case sensitive, hence suitable to M2M (machine-to-machine) transections.

Base-36 Comperession

1. max 13 charectets compression from 22 charecters hence 104 bits occupied.
2. It is case in-sensitive, hence suitable to H2M (Humant-to-machine) / M2H / H2H transection.

String-Formation for Geo-Coordinate (Latitude,Longitude)

-	8	9	.	9	9	9	9	9	9	,	-	1	7	9	.	9	9	9	9	9	9
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22

Maximum 22 characters are required to store location (currently precision is upto 6 decimals for general public mpas)

Place Holder	What it denotes?
1	Sign for Latitude
2-3 & 5-10	Digits for Latitude
4	Floating Point for Latitude
11	Seprator b/w Latitude & Longitude
12	Sign for Longitude
13-15 & 17-22	Digits for Longitude
16	Floating Point for Longitude

Separator-Index

Seprator index denotes where is seprator situated after removal of Floating point & Signs. It means its value = No of Latitude Digits - 1

for example,

Coordinates	Separator-Index
0,175.2	0
-89.999999,175.2	7

± Sign

Sign defines that from which octant, the cordinate belongs to. its index value ranges from 0 to 3.

Sign	Sign-Index
+latitude, +longitude	0
+latitude, -longitude	1
-latitude, +longitude	2
-latitude, -longitude	3

Decimal-Index for Folating Points

Floating Points may be in Latitude & Longitude both.

Floating Point in Latitude

Latitude	Place-Index(lat)
0	0
89.9	1

Floating Point in Longitude

Longitude	Place-Index(lon)
0	0
17.99	1
179.9	2

Resultant Decimal-Index Matrix

Place-Index(lat)	Place-Index(lon)	Decimal-index
0	0	0
0	1	1
0	2	2
1	0	3
1	1	4
1	2	5

Encoding Logic

1. Defigning Sign-Index for given coordinates & then removing signs.
2. Defining Decimal-Index for coordinates received thru step-1 & then removing floating points.
3. Defining Seprator-Index for coordinates received thru step-2 & then removing seprator.
4. Encoding big number received thru step-3 for Base-36/62.
5. Concatanating Sign-Index & Deciimal-Index, then encoding them to Base-36/62.
6. Concatanating followings in sequence :
   • Encoded number received thru step-4
   • Sperator index received thru step-3
   • Encoded Charecter received thru step-5

Further development

1. Currently, Seprator-Index is not encoded because its max value is considered 7, but if decimals digits in Lat increases, it can be encoded
2. Encoding-Decoding functions are developed for client side in Javascript. which can be made for server side languages as well as device side platforms (like android)

Special Thanks

For handling bignumbers in javascript, I gone thru various libraries & their performance test result. Finally came accors @MikeMcl's bignumber.js library which I found best according to performance & usability.