In most of the world, geographic data is built on open, global standards. Systems like the World Geodetic System 1984 (WGS 84) act as a common language, allowing anyone from a software developer to a hobbyist to create and share accurate maps.
In the People’s Republic of China, geographic data is a tool of state control. The Chinese government intentionally rejects global standards and enforces its own proprietary and distorted coordinate system, known as GCJ-02. This system is not a technical upgrade; it is a digital barrier designed to control information and, most significantly, to prevent ordinary Chinese citizens from mapping their own country.
The GCJ-02 Standard
The GCJ-02 system is the legally mandated standard for all maps used within China. At its core, it is based on the WGS-84 standard, but with a crucial difference: the Chinese state applies a secret, non-linear algorithm to every coordinate.
This algorithm systematically shifts latitude and longitude points, introducing artificial errors that can range from 50 to 500 meters. The distortion uses complex trigonometric functions to make the shifts appear random, preventing a simple conversion. The result is that a standard WGS-84 GPS coordinate, when plotted on a Chinese map, will appear in the wrong location. Satellite imagery will not align with street grids.
The intent is clear. This is not for technical enhancement or to protect a legacy system. The purpose is obfuscation. The fact that the conversion algorithm had to be reverse-engineered by programmers outside of China proves that its goal is not interoperability, but to create a closed, state-controlled information ecosystem.
Mapping Your Own Street is a Prohibited Act
The technical barrier of the GCJ-02 system is enforced by severe legal prohibitions aimed directly at everyday people. The most aggressive restriction is the state’s ban on private surveying and mapping.
Under Chinese law, a private citizen is forbidden from creating maps. This regulation is not limited to large-scale commercial activity; it applies at the most basic level. An individual cannot legally survey their own neighborhood, track a hiking trail with a standard GPS device for public sharing, or contribute data about a new local shop to an open map. The simple act of documenting one’s own surroundings with geographic coordinates is reserved for the state and state-approved entities.
This has a chilling effect on citizen-led initiatives. Collaborative, open-source projects like OpenStreetMap, which rely on volunteers to map the world, are effectively off-limits for domestic contributors in China. While a person in another country can add to the map of China without issue, a Chinese citizen doing the same faces legal punishment.
Combination of technical and legal measures
The combination of the GCJ-02 coordinate system and the strict anti-mapping laws serves a single purpose: to ensure the state is the sole source and arbiter of geographic truth. By preventing its citizens from independently collecting and sharing map data, the Chinese government asserts absolute authority over how the nation is depicted.
This strategy effectively makes accurate, independent cartography a criminal act for 1.4 billion people. It denies ordinary citizens a fundamental tool for understanding, documenting, and interacting with their own environment, reinforcing state control over both the digital and physical landscape of the nation.
Related and useful links
https://en.wikipedia.org/wiki/Restrictions_on_geographic_data_in_China
https://wuyongzheng.github.io/china-map-deviation/paper.html
https://wuyongzheng.wordpress.com/2010/01/22/china-map-deviation-as-a-regression-problem/
https://github.com/baijs/GCJ02-Coordinate-Transformation
https://github.com/googollee/eviltransform
Tags: China
