Geodetic Coordinate System 2002(GCJ-02)

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Introduction

Geodetic Coordinate System 2002, also known as GCJ-02 or nonlinear confidentiality processing technology for topographic maps, is a coordinate system for geographic information systems developed by the China National Administration of Surveying, Mapping and Geoinformation in 2002. It is an encryption algorithm for longitude and latitude data. By adding random deviations, the real coordinates are encrypted into false coordinates to achieve the confidentiality of geographic information. The Mars coordinate system is widely used in domestic map services, such as Amap and Baidu Maps, which must use this coordinate system to encrypt geographic locations.

Data Representation

Data in the Geodetic Coordinate System 2002 is usually represented as a series of numbers or strings, and the specific format may vary depending on different applications or platforms. The following are some common representations:

Numerical representation:

Longitude: such as 116.397128°

Latitude: such as 39.916527°

Altitude (optional): such as 50m (indicates 50 meters above the ground)

String representation:

Combination of longitude and latitude: such as “116.397128,39.916527”

Combination of longitude and latitude and altitude (optional): such as “116.397128,39.916527,50”

Pros

1. Strong confidentiality: GCJ-02 converts real coordinates into false coordinates through encryption algorithms, thereby effectively preventing the leakage and abuse of geographic information.

2. Wide application: As the standard coordinate system for domestic map services, GCJ-02 is widely used in various map applications and geographic information systems.

3. Ensure national security: The use of the GCJ-02 can strengthen the control of domestic geographic information, prevent important geographic information from being obtained and used by external forces, and thus ensure national security.

Cons

1. Coordinate offset: Since the GCJ-02 is obtained by adding offset to the real coordinates, there will be a coordinate offset when it is used. This may affect some applications that require high-precision positioning.

2. Complex conversion: Converting other coordinate systems to the GCJ-02 requires certain algorithms and technical support, which may increase some technical difficulty and cost.

3. Restriction on freedom of information: Although the GCJ-02 can ensure the confidentiality of geographic information, it also restricts the free flow and sharing of information to a certain extent.

Application Scenario

Due to the needs of national security and information confidentiality, various domestic map systems (including electronic forms) must use GCJ-02 to encrypt geographic locations for the first time. Therefore, GCJ-02 has become the standard coordinate system for domestic map services. GCJ-02 has been widely used in the fields of domestic map services, navigation and positioning. These applications usually need to process a large amount of geographic location data and ensure the accuracy and confidentiality of the data. By using GCJ-02, these applications can provide users with accurate geographic location information while preventing the leakage of sensitive information.

Example

Overview of GCJ-02.

GCJ-02 transformation plugin for QGIS.