Wednesday, October 19, 2005

The definition of “easy usage” that Locapoint aim to be (The Story of Locapoint: 4)

The definition of “easy usage” that Locapoint aim to be

I have to define the meaning of “easy usage” for Locapoint, in another word, the significance of existence of Locapoint.

First, I re-consider merits and demerits of traditional latitude/longitude format. One of demerit is of course its length. That is why many ‘geo-codes’ are developed. In addition, other demerits are

1.Needs two data (latitude and longitude) to specify a location
2.Variable formats
3.Variable datum

On the other hand, merits are
1.Can be used at any precision level
2.Global availability
3.Values and physical location is continuously related. Increase or decrease in value in latitude/longitude can be intuitively related to physical location movement to North, South, West, and West.
4.Can locate on map, without electronic devices

Reviewing characteristics of traditional Lat/Lon format, it is not bad. Many ‘Geo-Codes’ is certainly shorter than Lat/Lon, but sacrifices most merit of Lat/Lon format. May Geo-code require electronic devices to encode/decode, and code-place relativity is not intuitive.

When I start developing Locapoint, I was about to startup a kind of ‘distress call dispatching service’ business. So, Geo-code that can’t be easily decoded into Lat/Lon without electronic devices is out of my option, because I mainly consider emergency or distress situation usage.
I also focuses on audio recognize ability. I imagine a emergency situation, digital devices are down or out of battery, and only you can use is ‘primitive devices’ such as telephone, walky-talky, Radio communication, or similar ‘analog audio’ devices.
If Geo-code is confusing, miss-listening the code could cause fatal result.

From this viewpoint of “easy usage for human”, I require Locapoint following restrictions.

1. Easily decodable to latitude and longitude with calculator.
2. Easy to read, say, listen.
3. Global availability.
4. Enough precision (hopefully, less than one meter = 3 feet)
5. Relativity between code value and physical location is intuitive.

These are very difficult conditions to realize. How other Geo-Codes is doing. What is merit and demerit of them?

Next, I’m going to introduce other ‘Geo-Codes’.


Data compression technique and length compression (The Story of Locapoint: 3)

The method to shorten display length using large base of radix (more than ten) is called digit length compression. I wrote about it in my previous post.

These is a similar word, "data compression". (Concept is different, though).
I consider about losslessly data compression techniques large file could be compressed a lot. In fact, there are lots of compression techniques in IT world. zip, cab, or tgz are a very popular extension for compressed file.
However, latitude and longitude for a point with 1 meter precision is only 50 bit. In byte, it only 7 bytes. Latitude and longitude for any place on earth means, data could be random value. Then 50 bit is minimum requirement. Data compression technology can't be used for single location data.

There is another way to 'fake' compression. Like G-Code on video recording, assign small number for frequently used object. For example, major channel, high viewing rate time, fixed record time (like one hour, two hours) will be assigned small number. When G-code is "23", it originally comes from "0000000000023" etc. (I don't actually know about G-code length). If you want record a minor TV-program, its G-Code should be long and close to original length.
Similarly, Major street in Paris is assigned a short digit, so address will be short and simple.

With this concept, Location code could assign short and convenient code to major cities, and assign longest code for ocean area.
"MAPCODE" designed by Denso Co. in Japan use this concept. Assign short number to Tokyo area, so any location in Tokyo can be expressed in 4 digits of numbers. But in country side, it needs 10 digits.

This method needs "assign" information between area and codes to encode/decode. In fact, if you want to use MAPCODE, you need to buy data from Denso Co.

I have written about demerit of latitude/longitude format. "too long".
However, what is the Merit of traditional latitude/longitude format ?

When someone is in distress in sea or mountain, Lat/Lon format is generally used for SAR(Search and rescue) operation. If you send a mayday with "MAPCODE" and SAR entity didn't buy a assigned data?
The biggest merit of Lat/Lon format is its generality.

I tried to create a code for "easy usage" but now I have to define what is "easy usage".

Next, I will write about my definition of "easy usage" for geographic location code.


Wednesday, October 12, 2005

Amount of information and Display length needed (The Story of Locapoint: 2)

To express ANY location on earth with about one meter (or 3.28 feet) precision, I calculated following.

Meridian of the earth is 40,000,000 meter, thus it needs 40,000,000 steps for 1 meter precision. Actually, it requires

20,000,000 steps in latitude direction (a half of meridian),
40,000,000 steps in longitude direction
= 8*10^14 steps

is required.

From technology's point of view, 8*10^14 steps is 49.507 bits of information.
To express this data, following length of digits is needed in various radix.

50 digits: binary notation (radix = 2)
15 digits: decimal (radix = 10)
13 digits: HEX (radix = 16)
11 digits: radix=26
10 digits: radix=36
9 digits: radix=60
4 digits: radix=10000

If I choose to create a code which is only using number, it requires at least 15 numbers. Like a credit card number (16 numbers), this is not easy to remember for human.

If I choose HEX notation (0-9 and A-E as 10-15), it needs at least 13 digits. it is shorter, but "28a6f6b021cf3" is NOT as easy to remember as telephone number.

If you know Chinese characters, and know 10000 characters, you may use only four letters for a code. This is much sorter, but it seems inconvenience. In addition, increasing in radix base doesn't look effective in decreasing display digits.

So, I had a two choice.
1. Decrease amount of information
with lower precision (like 30 meter or 100 feet)
by limiting cover area of the code (US only, Japan only, etc.)
2. Keep amount of information
but try to create a "Easy" code for human

Many existing code chose the first one. For example, "map code" by Denso Co. can express any location in Japan with 30 meter precision by 10 numbers. Or 3 meter precision by 12 numbers.

I wanted to create UNIVERSAL geographic code, then I had to choose the second one.
But at this time, I had no idea how to do it.


Tuesday, October 11, 2005

The Story of Locapoint

I'd like to record how Locapoint was born.

On 25th, October 2004, I was on a train from Nagano. I met a CEO of venture company in GIS (Geographic Information System) industry to ask some advice, because I was about to start up my own company next week.

I was on my way home to Nara from Nagano. That was a long trip. In a train, I was half-sleep, half-awake. I imagined situation like this.

I'm on my way to a bar to attend a party. But I don't know where the bar. I know telephone number, and I call the bar.
"Hi, I want to go there, but I don't know where you are. We,, I've got a latest cell-phone with GPS navigation. Tell me your latitude and longitude, so I can input them to my Navigator"
"Hey....We can tell you a direction but latitude and longitude!"

Who remember latitude and longitude of own home? Maybe no one.
But most people remember their telephone number. Why?

This question is the beginning of Locapoint Stories.

I thought, may be latitude/longitude is too long for human. There must be a limit in brain capacity to remembering, and it must be between telephone number (10 digits) and latitude/longitude (15-16 digits).

I thought about "G-code" that is used for VCR recording. G-Code is a compressed code that contains channel, start time, and end-time(or time length).

I thought I may develop a 'G-code' for location, so latitude/longitude information can be shorter than brain capacity limit. If people can easily use GIS information, so world will be more convenient!

I opened a lap-top, open excel, and start some calculation.


Saturday, October 01, 2005


Locapoint Website and "Direction Creator" is pre-opened today.
I announced pre-open to close friends.

I haven't had a enough sleep for a month to open this site...
There are lot of thing that I have to work on, but I'll take a rest tmorrow.

Thank you for comming to this blog.