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So it is known that the maps, either the regular street map or the satellite map, does not line up correctly in specific parts of China. So which map lines up correctly, the satellite map or the default street map? Some sites suggest that the satellite map is correct. But the Google Geocoder is placing locations correctly on the google street map and not on the satellite map. So if the satellite map is considered to be correctly aligned with China, does that mean that the Google Geocoder is also returning incorrect coordinates for locations in China? I have not been able to find any official document on this.

james
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2 Answers2

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Satellite image is correct. The government of China enforces a kind of non-linear shift to online map provider for security concern. You can see overlapped streets on the border of China. For example, populated border area on Hong Kong-China border, Macau-China border and Vietnam-China border are the proofs. If you are using Google map in China, there is another version report streets correctly.

OmniBus
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Based on my tests, only the street-map is shifted but the satellite-map is correctly aligned with the GPS coordinates. You can use http://ditu.google.com/maps?output=classic instead of the classic Google Maps.

In Google Earth you could try this overlay: http://ge-map-overlays.appspot.com/google-maps/china.

By the way, this is not only in specific parts of China maps, but in all China maps, and it seems to be due to some legal issues which Google never explained.

Nikita 웃
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  • Thanks for the response. How did you determine that the street map is correct? It sounds like you are using some known coordinates or where did you get the coordinates from? Do you know if the coordinates that you used are 100% correct? I'm just wondering if the coordinates from Google's geocoder is based on their street map, or if it is actually the exact coordinates of the location. Unfortunately I don't know anyone from China to confirm. – james May 14 '14 at 23:01
  • Yes, used my own coordinates from mobile while being in China. Fully tested. – Nikita 웃 May 14 '14 at 23:10
  • @james is my post missing something or not answering your question? if so, please let me know what additional info you need. – Nikita 웃 May 15 '14 at 05:56
  • Im looking for some official documentation relating to the accuracy of the satellite vs road map. So far I haven't been able to find any...many sites say that the satellite map is correct and the road is incorrect, while you are saying that the road is correct, and satellite is incorrect. So it makes it difficult to figure out if Google's geocoder is accurate for China – james May 15 '14 at 23:47
  • @james - Google is aware of the problem since 2009 and never released any official documentation or statements regarding this, thus the documentation you are looking for, as you may have noticed yourself, just doesn't exist. As for the accuracy of the maps in relation to the GPS geocoding, my answer is 100% correct, and has been tested first hand in 7 different Chinese provinces (while traveling in China) just a few months ago: On the map view - my exact location always matched the map but when I switched to satellite view - the image was shifted/misaligned. Always. – Nikita 웃 May 16 '14 at 06:01
  • I know this is an old issue. Wanted to ask, did you use your own coordinates from a mobile phone or gps system? Was the mobile phone/GPS system manufactured in China with the intent to be sold in China. In speaking with the Bing Maps Team, they are saying that the Satellite map is correct and the Road map contains a shift. If the gps system was manufactured in China with the intent of being sold in China, it will geocode correctly on the satellite map, and offset correctly to align on the street maps. If manufactured outside, then it will align only with the aerial, as intended – james Oct 29 '15 at 17:51
  • I have just returned back from China and had a chance to test again. This time it clearly showed that the satellite map location was correct, while the Basic map was always shifted. I have revised my answer accordingly. – Nikita 웃 Jan 17 '16 at 12:04