Nov 9 in History: Lost in Translation: GPS in China
/
RSS Feed
Introduction:
●
Start the episode by introducing the topic of GPS and map accuracy. Briefly explain how GPS works and its reliance on satellite signals.
●
Introduce the concept of map projections and how they can sometimes lead to slight discrepancies between digital maps and the real world.
●
Transition to the main topic: the unique situation in China where Google Maps and other mapping services display locations that are significantly offset from their actual positions.
The Discovery:
●
Recount blogger Jian Shuo Wang’s discovery of the offset in 2008 when Google added a traffic map feature to its China service.
●
He observed that while the traffic data aligned perfectly with the street maps, it didn’t match the satellite imagery, revealing a noticeable shift.
●
Wang’s investigation showed the real location could be anywhere from 0 to 500 meters north, south, east, or west of what’s displayed on the map.
Theories and Speculation:
●
Explore the various theories put forward in the blog’s comment section to explain the offset.
○
Intentional Distortion: Many commenters, including some claiming to be Chinese natives, suggest the Chinese government mandates this distortion for security reasons. The offset is seen as a way to make foreign maps less useful for military purposes.
○
Different Coordinate Systems: A commenter with cartography expertise argues the mismatch stems from China using a different coordinate system (Krasovsky or Xi’an 80) for its street maps compared to the WGS84 system used for satellite imagery.
○
Commercial Interests: Another theory is that the offset aims to protect the market share of local Chinese mapping companies by making foreign services like Google Maps less reliable.
Evidence and Examples:
●
Highlight the evidence presented in the blog post and comments to support the theories.
○
Apple Maps: Some users point out that Apple Maps on iPhones seem to be accurate in both street and satellite views, suggesting the problem isn’t with GPS itself but with the map data provided to Google.
○
ABC Maps: A Chinese mapping app called ABC Maps emerged, claiming to automatically correct the offset. This lends credibility to the idea that the distortion is deliberate and can be reversed with the right adjustments.
○
GPS Device Issues: Commenters sharing their experiences with GPS devices purchased outside of China describe experiencing the offset. This supports the theory of government control over GPS chips or map data.
Impact and Solutions:
●
Discuss the implications of the map offset for people living in and visiting China.
●
Mention the frustration and inconvenience it causes for navigation and location-based services.
●
Explain the emergence of solutions like ABC Maps and firmware patches for GPS devices.
●
Note that while the exact cause of the offset remains somewhat unclear, the sources strongly indicate it’s a deliberate measure, potentially for security or commercial reasons.
Conclusion:
●
End the episode by summarizing the mystery surrounding the Google Maps offset in China.
●
Reiterate the various theories and the evidence supporting them.
●
Leave listeners with a sense of intrigue and encourage them to research further or share their own experiences with mapping services in China.