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China maps out of alignment in Google

 
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Darren
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Joined: 11/07/2002 14:36:40
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Location: Hampshire, UK

PostPosted: Thu Aug 20, 2015 10:21 am    Post subject: China maps out of alignment in Google Reply with quote

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A number of sites and blogs have flagged an alignment issue in Google maps of China recently. Presumably sparked by searches to locate Tianjin, the location of the huge explosions last week.

If you view a map of China and overlay it on Google Earth you can quickly see that all the roads and streets are offset from their actual locations. It's even more obvious when you compare a Google Earth view over the border with Hong Kong where the alignments is correct on the Hong King side (as per the headline image above).

So why is this happening? The simple answer is - China. China requires that any mapping of its country observe the GCJ-02 coordinate system rather than WGS-84 used in the rest of the world. This uses an algorithm that offsets the map by random amounts. Google adheres to this requirement as it has a Chinese presence.

Why China insists on this is presumably down to security concerns. China has strict regulations regarding the creation of maps that are used in the country with severe punishments for anyone who flouts them.
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Kremmen
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Joined: Mar 03, 2006
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Location: Reading

PostPosted: Thu Aug 20, 2015 2:05 pm    Post subject: Reply with quote

Google driverless cars are going to be fun in China then as they make use of fairly accurate GPS locations Smile
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dales
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Joined: May 04, 2008
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Location: Knaresborough, North Yorkshire.

PostPosted: Fri Aug 21, 2015 5:50 pm    Post subject: Reply with quote

If using a Chinese map, you must use a satnav sold by Garmin China to match the offset.

If using a non-Chinese satnav, it's sometimes possible to get a venus-shifted map to match it.

Dales.
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MaFt
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Joined: Aug 31, 2005
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Location: Bradford, West Yorkshire

PostPosted: Mon Aug 24, 2015 12:33 pm    Post subject: Reply with quote

Kremmen wrote:
Google driverless cars are going to be fun in China then as they make use of fairly accurate GPS locations Smile


I would hazard a guess that any Chinese driverless car would be set to use China's own Beidou positioning system as well as government 'approved' maps.

MaFt
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