
The China GPS shift problem - minouye
https://en.wikipedia.org/wiki/Restrictions_on_geographic_data_in_China#The_China_GPS_shift_problem
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csense
It also links to
[https://en.wikipedia.org/wiki/Restrictions_on_geographic_dat...](https://en.wikipedia.org/wiki/Restrictions_on_geographic_data_in_China#Legislation)
which says "private surveying and mapping activities have been illegal in
mainland China since 2002."

So gathering data for crowdsourced maps like OpenStreetMap is illegal unless
you get the Chinese government's permission.

I wonder why? And also, how they could possibly enforce it -- if you drive
around with GPS logging turned on and don't tell anybody, how do they find
out?

EDIT: According to
[https://en.wikipedia.org/wiki/Restrictions_on_geographic_dat...](https://en.wikipedia.org/wiki/Restrictions_on_geographic_data_in_China#GCJ-02)
it "uses an obfuscation algorithm which adds apparently random offsets to both
the latitude and longitude, with the alleged goal of improving national
security."

True, there are probably legitimate military reasons to keep accurate maps of
your territory out of the hands of potential enemies. But surely any country
thinking of attacking China with, say, GPS guided missiles / bombs would also
be quite capable of getting an accurate map with satellite imagery, or for
that matter, a few agents carrying ordinary smartphones with GPS logging
turned on...

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cr0sh
I doubt it has anything to do with foreign adversaries, and more to do with
control of the internal population in some manner.

I tend to wonder how they'll get self-driving vehicles to work over there (hmm
- I wonder if there are any Baidu papers on this issue available?)...

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trapperkeeper74
Good GPS receivers allowed changes to datums. Furthermore, there is a
transformation possible between ellipsoids if you have their exact parameters.

Source: I worked at Trimble.

~~~
thisrod
I agree. How is this different from all the other failures caused by false
assumptions about map datums? (And why aren't those just another case of bad
metadata, comparable to character encoding issues?)

Edit, read the rest of the article to put the linked section into context. The
commies are trying to obfuscate a _map grid_? That's just nutty. Are they
really going to arrest everyone who is found in possession of a magnetised
needle?

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Taniwha
For a great example of this look at the border between Hong Kong and Shenzhen
on plain google maps ... turn on the street map layer, then the satellite
layer - they match on the HKG side of the border, but not to the north in
China

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peterburkimsher
This was an issue in earlier versions of Galileo Offline Maps.

[http://idea.galileo-app.com/?ia=20787](http://idea.galileo-app.com/?ia=20787)

