Global Navigation Grid Code

The Global Navigation Grid Code (GNGC) is a Chinese developed point reference system of grid references commonly designed for the global navigation. It is similar in design to the national grid reference systems used throughout other nations. The GNGC was developed based on the work of GeoSOT team in Institute of Remote Sensing and GIS, Peking University. The concept was first proposed in 2015 in Bin Li's dissertation, Navigation Computing Model of Global Navigation Grid Code.

Conception

English: Global Navigation Grid Code(GNGC) Chinese: 全球导航网格码 Definition: The code based on global grid for navigation is called Global Navigation Grid Code(GNGC). In the research of global spatial information sub-division, global navigation grid code is a geographic grid coding model with characters of multi-scale, discrete and suitable for navigation service. The grid coding model can not only solve the problem of navigation and positioning related, but also solve the problem in organization, integration, sharing and efficient service of spatial information.

Subdivision Method

The subdivision method for Global Navigation Grid Code

The GNGC is based on GeoSOT (Geographic coordinate Subdivision grid with One dimension integer coding on 2ⁿ Tree) theory. GeoSOT has some extensions:

Extension 1: Normally 1°=60′，here we extend 1°=64′;

Extension 2: Normally 1′=60″，here we extend 1′=64″

The purpose to make above extension is that 64=26, it will be easy for subdivision by a quad-tree method and will be good for computer to do simple binary operation.

Generally speaking, GNGC’s subdivision is to subdivide the earth surface by Longitude difference and Latitude difference. The subdivision contains total seven steps:

Step1: The first step of subdivision is according to the standard 1:1000000 international map. The cross point of the equator and the Greenwich meridian is set as the origin point. For the northern and southern hemispheres, use N and S to present the first code for each grid. For the latitude direction, use number 1-60 as the grid code; for the longitude direction, use A-V as the grid code. From this step, the 1:1000000 international map is divided by 6°×4°grids covering the area between north latitude 88° and south latitude 88°. For the Polar Regions other coding method will be used, which will not specify here.

After this step, we get 60×44 grids, each grid is 6°×4°. For example, we can get a grid with the code N32G as shown in Figure 1.

Step2: Divide the 6°× 4°grids by 16'×16' grid. Since we have extended 1° from 60′ to 64′, we can get integral 24×16 grids for each 6°× 4°grid in this step (6×64/16=24, 4×64/16=16) . The 16'×16' grid is about 32km×32km ground size in the corresponding earth surface near equator. And the coding method in each quadrant is as following: In North-east hemisphere, give each grid a code of one English alphabet by using A-X from left to right and A-P from bottom to top; In South-east hemisphere, give each grid a code of one English alphabet by using A-X from left to right and A-P from top to bottom; In South-west hemisphere, give each grid a code of one English alphabet by using A-X from right to left and A-P from top to bottom; In North-west hemisphere, give each grid a code of one English alphabet by using A-X from right to left and A-P from bottom to top; For example, we can get a 16'×16' grid with the code N32GEH.

Step3: Divide each 16'×16' grid to 4'×4' grids. And for each 4'×4'grid, use one English alphabet of A-P to define the grid code. The 16'×16' grid is about 8km×8km ground size in the corresponding earth surface near equator. Since we have made extensions of 1° from 60′ to 64′, there will be some grids (grids no color) which is not actually existing in the real world. In this step, we can get a 4'×4' grid with the code N32GEHD.

Step4: Divide each 4'×4' grid to 32″×32″grids. Since we have extended 1′ from 60″ to 64″, we can get integral 8×8 grids for each 4'×4' grid in this step (4×64/32=8, 4×64/32=8) . And in this step we code the grid by two numbers by using 0-7 from left to right and 0-7 from bottom to top. For example, in this step we can get a grid with code N32GEHD42. The 32″×32″ grid is about 2km×2km ground size in the corresponding earth surface near equator.

Step5: Divide each 32″×32″ grid to 4″×4″grids. In this step we code the grid by two numbers by using 0-7 from left to right and 0-7 from bottom to top. For example, in this step we can get a grid with code N32GEHD4723. The 4″×4″ grid is about 128m×128m ground size in the corresponding earth surface near equator.

Step6: Divide each 4″×4″ grid to 1/2″×1/2″ grids. In this step we code the grid by two numbers by using 0-7 from left to right and 0-7 from bottom to top. For example, in this step we can get a grid with code N32GEHD471236. The 1/2″×1/2″ grid is about 16m×16m ground size in the corresponding earth surface near equator.

Step7: Divide each 1/2″×1/2″ grid to 1/32″×1/32″ grids. In this step we code the grid by two numbers by using 0-7 from left to right and 0-7 from bottom to top. For example, in this step we can get a grid with code N32GEHD47102366. The 1/32″×1/32″ grid is about 2m×2m ground size in the corresponding earth surface near equator.

After the seven subdivision steps, we can get the grid code from levels of globe to 2-meter size. The 2-meter size is detailed enough for navigation application and other related public data management.

Origins

From 2009-2013, research team in Institute of Remote Sensing and GIS at School of Earch and Space Science in Peking University, together with Wuhan University, Information Engineering University, Chinese University of Science and Technology, National University of Defense Technology finished the National 973 Project "Global Spatial Information Subdivision Theory and Application Method". In this research,the team proposed a global subdivision grid fram: Geographic coordinate Subdivision grid with One dimension integer coding on 2ⁿ Tree (GeoSOT). This work primarily solved the three big scientific problems in the spatial data organization : basic fram, location code and presentation model. GeoSOT is a grid system from center point of earth to 50000 km faraway outer space. And this grid system subdivided the earth space by 32 levels to millions of small grids of centimeter size. A total of 28 patents applied and published a work Introduction to Spatial Information Subdivision.

In the project, the research team proposed a complete area location coding system called "1+4 basic code, N serial extended codes". Above these codes, the global subdivision grid code is a basic job and completed already. Current research is grid codes on remote sensing, GIS, navigation and internet, and make proposals and methods to industry and departments. Global navigation grid code is one of the topics in the research frame for navigation application. Global navigation grid code was first proposed into public in Bin Li's dissertation for doctor degree Navigation Computing Model of Global Navigation Grid Code. IT is a primary research and exploration for the application of GNGC for navigation.

Research background

Global Navigation Grid Code is part of research on Global Sub-division Grid(GSG). GSG is also called global descrete grid, a reference grid system by subdividing the earth surface into samll pieces of grid cells by certain rules(also called geographic grid or spatial information grid). The research of GSG contains the methods of how to subdivide the earth(or earth surface) to the grid cells with same area and same shape of different levels. Through further research on mathematic modeling and algorithm, GSG improves the proficiency on the spatial informaiton presentation and data organization. Today, with the progress in mathematic tool and computer sicence and technology, global sub-division grid is one of the key method in the research of Geo-information Science.

Global Subdivision grid has a lot of potential applications and has been applied in some fields. For example, the expression of complex geographical phenomena can be studied in complex geological problems. For the expression of natural and human data, the problem of human society can be studied. For the expression of the function and behavior of the geographical system, the relationship between human and land can be studied. With the development of modern technology, the method of earth observing has been developed by leaps and bounds, thus promoting the application of GSG. The role of GSG has evolved from the traditional map location framework and the expression of geographical phenomena to a new level. Main applications include the new application of geographic spatial data fusion, multi-source data fusion, geo-science comprehensive analysis and so on.

In China on the basis of the actual situation of their own, Chinese research team in Peking University designed GNGC that conforms to the habit of Chinese country industry application, easy to calculation of space and spatial index, and can be further extended to the global use of navigation mesh coding. It is necessary and this demand is to replace foreign trellis coded. With the establishment and improvement of the Beidou navigation system, to develop a new navigation grid code with independent intellectual property rights, globally applicable standards and global navigation trellis coded has important strategic significance. It can rise to the height of the China will. Due to the natural advantage of the global partition model in spatial location, it is feasible to build the global grid and design the grid and its coding for navigation applications based on the earth subdivision model.

Functions

Global navigation grid code can not only be applied to navigation, but also can be applied to many departments and fields. It has strong application potential and value. From the reality of the situation, human activities on the demand for spatial information and dependence is getting higher and higher, a variety of new information applications are emerging, has been showing a big data, information explosion characteristics. In particular, location service data, because of its extensive use of the data, resulting in a huge amount of data and update speed. According to statistics, a prefecture level city alone, mobile location service data and the data to be added daily volume reached more than 1 billion. At the same time, to increase these big data rapid growth has not brought the corresponding value of the message. On the contrary, the world for the use of these data is very low income. Due to technical and some subjective factors, the number of spatial information is divided, use and waste, and useful to human activity information is often difficult to get comprehensive, timely and accurate. Especially, for human by the age of the Internet into the mobile Internet era, with all can be wearable devices and mobile terminal, a lot of social perception data can be seen, these human societal perception of big data analysis and processing has become an important research focus.Therefore, how to more effectively to global, massive, high dynamic spatial information were acquisition, storage, computing, processing, and call (i.e., organization), allows users to truly realize the "according to need" to be comprehensive, timely, accurate and useful spatial information has become a key subject in the modern information technology development.

Global navigation grid code can not only mark the location, but also can identify areas to meet the massive spatial information only, in the position of elements on the expression of multi-scale and hierarchical Association, and seamless non overlapping requirements. And the truing number coding design can greatly simplify the location area identification, expression and calculation, and traditional the latitude and longitude of identity are not contradictory, the existing based on latitude and longitude, and vector network navigation system a good supplement and perfect.

With the development and application of satellite navigation and positioning technology, digital map, digital street map, wireless communications and other technology, especially the popularization of vehicle navigation and portable navigation terminal, it will be great practical value to design new navigation coding method and related service models to meet the navigation aplication demands according to the characteristics of satellite navigation system.