wgs-84 vs gcj-02

gps

• two coordinate systems, WGS-84 is the most common, but china uses the GCJ-02 system
• GCJ-02 system includes an algorithm to obfuscates the results
• there are some open source libraries to convert from one to the other
• this is why google maps is slightly off in china by around 50m, roads are slighty off
• https://ihatecoordinatesystems.com/
• https://www.youtube.com/watch?v=L9Di-UVC-_4