The Natural Area Coding System

THE NAC GEOGRAPHIC AND GEODETIC INFORMATION MANAGEMENT SYSTEM

Since The Natural Area Coding System has generated simple NACs for all areas on the earth and three-dimensional regions in the universe and short coordinates for all geodetic points, the system can significantly improve the structure of a geographic or geospatial database and reduce its storage size more than 80%. One of the structures of the system for managing a geographic database is described in the following:

A NAC geographic information database for the whole earth surface stored in a computer contains two main directories. The first main directory is called the main NAC directory under which all geographic information is saved according to the NAC structure. The second main directory is called the main index directory under which all the information about geographic identities are linked to the NAC areas and the information about these identities can be retrieved from the NAC directories through the linkage.

The main NAC directory contains several files and first level NAC directories. The files are the information of the global geographic identities such as continent borders, ocean borders, country borders, global transportation networks, etc. The first NAC level directories contain the information of the first level NAC areas and named by the NAC of the first level NAC areas with a lower case hypen to link the two parts of a NAC such as N_K for NAC: N K. There are 900 first level NAC areas on the earth, so there will be 900 first level directories under the main NAC directory.

A first level NAC directory contains several files and second level NAC directories. The files are the information of the geographic identities of the size suitable to be shown on the first level NAC area map such as country borders, rivers, province borders, forests, deserts, etc. The geodetic coordinates of the geographic identities will be saved in relative NACs of the first level NAC area such as the absolute NAC of a geodetic point at NAC: NJKL KGDF will be saved as "JKL GDF" under the first NAC directory named by N_K. This arrangement can save lots of required memory. A second level NAC directory containes the geographic information of the second level NAC area and named by the relative NAC of the second level NAC area such as the second level NAC directory for the second level NAC area of NAC: NJ KG will be named as J_G under the first level NAC directory named by N_K. There are 900 second level NAC directories in total.

A second level NAC directory contains several files and third level NAC directories. The files are the geographic information suitable to be shown on the second level NAC area map. All the geodetic coordinates of the geographic information will be saved in relative NACs such as a geodetic point at NAC: NJKL KGDF will be saved as "KL DF" under the second level NAC directory named by J_G under the first level NAC directory named by N_K. A third level NAC directory will be named by its relative NAC such as the third level NAC directory for the third level NAC area of NAC: NJK KGD will be named as K_D under the second NAC directory named by J_G under the first level NAC directory named by N_K.

A third level NAC directory will be created in the same way as the second level NAC directory, so do a fourth or fifth level NAC directory.

The geographic identities such as a straight line section of any length parallel to the lines of constant longitude or constant latitude or an area of any size and any side ratio bounded by lines of constant longitude and constant latitude can be simply represented by a single NAC such as NAC: HJKL KG and NAC: HJKL KG--K are straight line sections while NAC: HJK KGD and NAC: HJK KGD-F are areas. These notations can save a lot of memory to represent these geographic identities. Many state and county boundaries in the United States are straight line sections parallel to the lines of constant longitude and constant latitude.

The second main directory is the main index directory which containes an index file and first level index directories for global geographic identities such as oceans, countries, etc. The index file lists all the names and their variations of the global geographic identities with their sequence indexes alphabetically. The sequence index of a global identity is a 30-based number expressed by 30 NAC characters. The index file contains the names of global geographic identities and their indexes with one line for one geographic identity. For example, a line for the United States in the file may look like:

United States of America; US; USA; United States; 23B

where the first one is the official name, and others are its variations, and the last one is the index. The index uses only NAC characters to make it shorter than only numerals. Excluding vowels is to eliminate combinations to be words. The indexes will be used as file names in NAC directories.

A first level index directory for a geographic identity will be named by its sequence index.

A first level index directory contains one index file and second level index directories for its second level geographic identities such as provinces, states, etc. The index file lists the NACs of the NAC areas covering the geographic identity on the first line and lists the names and their variations of second level geographic identities with their sequence indexes alphabetically. The second level index directories are named by their indexes listed in the index file.

A second level index directory has the same structure as the first level index directory, so does a third or fourth level index directory.

The name of a file in a NAC directory will be the absolute index of its corresponding geographic identity defined in an index directory plus an extension. The index will function as the key between NAC directories and index directories.

The indexes in the index file in the main index directory will be directly used as the file names in the NAC directories because they are already absolute indexes, while indexes in the index files in sub index directories will be prefixed by its directory name, parent directory name, or even its grand parent directory name because these indexes are relative indexes and the names of index directories under the main index directory are named by their relative indexes. For example, an geographic identity with index of 583 listed in an index file at

Main Index Directory/23B/4H7/Q8R/index.txt

Its detail description files in a NAC directory will be named as:

23B_4H7_Q8R_583.ext

where ext can be any extension you want to distinguish different files about the geographic identity.

When you try to find this object, you can first look up it in the index directories and find its index and the NAC it resides in. Then go to this NAC directory to find all files about this geographic identity.

A user interface for the database may allow the user to input either a NAC of an area or a name of a geographic identity to retrieve the geographic data. If a NAC of an area is input, the computer will directly go to the NAC directory to retrieve the data. If a name of a geographic identity is input, the computer will go to the index directory to find out the NACs of the NAC areas covering the geographic identity, and then go to the NAC directories to retrieve the corresponding data.

There are many significant advantages of the NAC system over other databases:

Using absolute NACs to represent geodetic points can save about 50% of memory compared with using other systems;
Using absolute NACs to represent straight line sections parallel to the lines of constant longitude or constant latitude can save more then 75% of memory;
Using absolute NACs to represent rectangular areas with the sides of constant longitude and constant latitude can save 87% of memory;
Using relative NACs to represent geodetic point, straight line sections or rectangular areas can save even more meomory.
If a 5-bit integer is introduced to represent a NAC character in the computer program, there will be another 40 percent of required memory to be saved when the geographic data are stored as binary files.
Using NACs to name the geographic database instead of direct using names of geographic identities can easily link the geographic information between neighboring geographic identities without the overlaps of geographic data;
Using NACs to name the geographic databases allows users to retrieve their interesting areas directly by typing in very few character NACs;
The system can also help users to store their own geographic data into the database efficiently if it includes a function for users to view and edit the database since the database structure is so systematic that any geographic data can be saved as a feature file under the directory named by the NAC of the area. Therefore, a NAC geographic information management system is a progressive system which can be updated by users all the time.

A NAC geodetic information management system for a three-dimensional database can be constructed in a way similar to a NAC geographic information management system for the earth surface, using the NACs of three-dimensional NAC geodetic blocks instead of two-dimensional NAC geographic cells as the directory names. The three-dimensional system will be even more efficient than the two-dimensional NAC geographic information management system because of the higher efficiency of the NACs in representing three-dimensional regions.

With so many significant advantages, the NAC geographic and geodetic information management system will be the most economic, efficient and user friendly geographic and geodetic information system.