There are rumor that all printed maps that is available in domestic market are transformed. The goal is to make the map useless for military situation to protect the safety of the country.
I heard about it but I didn’t really believe it. I thought to protect the country from foreign intelligence agents by transforming all maps available in a country is just a fool decision.
I do know that in certain Shanghai map, because of the streets in downtown is so crowded, and in other places, density is lower. So they transformed the map to cover as much as places possible while keep the downtown street clear enough to recognize.
However, the rumor is not about this specialize map. It is about all maps in China.
Google Map Revealed the Secret
In most places in China, Google map has a feature to hybrid map and satellite images. I found that handy. In China, however, there are no this feature.
Recently, Google added traffic map. When traffic map overlaid on top of local map, it fits each other perfectly. If the map is overlaid on a satellite map, you see the huge transformation.
Google Traffic on Map
Look at this: the traffic line and the map fit each other perfectly. You see the yellow line as Huashan Road – the road before where I work, and the green thin line is Huaihai Road, and the upper left double green lines are Elevated Highway.
Google Map on Satellite Maps
Look at this again.
The traffic lines are still there, but if you see the reality – the satellite image, you will find out the maps are completely transformed. The real Huashan Road is about 300 meters west of what is shown on the map, and the Huahai Road is actually 200 meters north of it. Meanwhile, it is not a consistent transforming – it is very random.
I checked other maps, and my conclusion is:
Look at a Chinese map, the real location may be 0 – 500 meters north, south, west, or east (randomly) of what the real location is. You have no idea about where the real location is because the transform is random.
It is Not a Problem of a Map Provider
Is it the error of a single map provider? In this case, is mapabc.com, the map source that provided the wrong data? I don’t think so. I talked with Google people about this, and talked with map expert. It seems all the maps are transformed.
I Hope We Release Real Map
Civil usage of GPS was once forced to add some noises so it is not accurate as GPS technology can provide. Now, the ban was lifted, and people can get knowledge of where they are via GPS.
I don’t think today, we can protect anything just by transforming a map. It reminded me about the claim of many local "map experts" that Google maps has released the national secret of China. I think the real national secret is, how narrow minded the "experts" are.
If the rumor is true, then how can GPS device work in China?
I enjoy reading your blog -thanks for the interesting posts.
However, while some maps are altered (in the UK, where I’m from, the standard OS maps miss many details close to armed forces bases, etc) and I’m sure it happens in China too, the Google Maps issue you’ve spotted is not down to this.
The transformation is due to a different map projection type being used on the map source used by Google. If you’re interested you can read about map projections here: http://en.wikipedia.org/wiki/Map_Projection.
I live in SH and use a Internet Tablet / GPS device which takes it’s images from maps.google.com (and ditu.google.cn) and I have to set an “offset” to show the maps in the correct location. The offset is not random, it is the same deviation N/E every time this map source is used.
i will be in Shanghai soon too and also face the problem with the offset i have seen on Google Maps. Can you tell me how you did this in your software and maybe provide some offset data for me?
So is it true the Map data is correct and only the satellite images are mapped wrong due to the projection method google uses?
Thanks in advance
PS: Maybe we can meet in Shanghai in March when you tell me the coordinates. Then you can show me. :)
@Dagobert, if you just need to get directions, the transformed map is OK since the relative locations of the map is workable for you. However, if you use GPS, that can bring a big problem.
That means GPS isnt working in Shanghai (for example)? How can there be Navigationsystems for cars? Or do they get real maps? I did a fast check on Johns offset tip and it seems everywhere is the same offset. So this would lead to my assumption the streetmap is accurate like he mentioned but not the mapping of the google satellite view. Maybe its really only a projection problem of google?
yeah I noticed on my Iphone….basically the SATELLITE VIEW show the correct position, instead the MAP is offset.
the bad thinks is the “direction function” is based on the map and not on the satelllite so basically the device will ask you to turn when it’s yet too late or too early creating a big mess!!
how come no one talk about this? :( I want t ouse my Iphone as GPS!!
thanks for your help
You’re not alone Gio. I am in Guangzhou and it’s the same thing. The GPS of the satellite view is perfect. Switch it to map view and I’m off 300-400 meters of where I’m suppose to be.
This really sucks as I can care less about the satellite view. I wish there’s a way we can set the offset in Maps in my iPhone but I don’t see many people care about it to even talk about it. I can’t find anything in google about this at all.
This is actually the first site I found that talked about it but I was actually searching for “How to report google map problem”. : /
If you’re using an Android mobile and get trouble on the incorrect my location because of the transformed maps, just try this application: http://sites.google.com/site/hereimapp/english
I am using HTC magic and also have this issue. But today(Jun 16), I update google map program from “market”. It seems this deviation issue fixed.
Friends with Android phone, take a try and see if your problem fixed.
So finally, I found some other people with the same frustrating experience as me! It’s been driving me crazy and I keep re-installing my software hoping to see a difference… the latest 3.0 update still didn’t help with the offset, but made it really clear on my iphone where the offset was once i could see the traffic maps. And just to reiterate, it is the MAP that’s offset, the SATELLITE is perfect.
So if China Unicom is going to launch the iPhone in China later this year, should we expect a fix to this soon? Otherwise you’re going to have millions of people with legitimate phones who are going to be pissed the GPS functions blows chunks. Since I had to “hack” mine to work, I accept a certain loss of functionality or convenience… but not for long.
Interesting posts. I bought garmin nuvi road gps abroad and had also issue with offset in map (indeed in NW direction, 300-400m [in Wuxi]). Through garmin service guy (who is friend of me) I got the solution which is a small piece of firmware that corrects the map offset (offset different over china?). The china maps (in this case garmin china map, maybe/probably same source as google maps?) all have offset.
The reason for this seems to be that locally made GPS devices are all corrected via firmware for this offset. So either they want to protect local gps brands or it has to do with military reasons that all maps have offset (which sounds like an outdated method anyway)?
I also have other (foreign) gps device which has exactly same offset (so the offset is definetly in the maps, not in the gps). Did not find any solution for e.g. google maps or google earth (if you have an easy way to “calibrate” either the maps in google maps or the tracks with offset, then let me know)
I have seen this problem for some time with GPS data in Beijing, Guangzhou and Shanghai. You can also see problems with road mismatches at Chines borders. Can anyone confirm how maps are behaving on the iphone now being sold in China? And do you see this problem also on Yahoo maps? Microsoft Bing?
Use http://ditu.google.com/ and the problem appears to go away. It’s strange as both ‘ditu’ and ‘maps’ use data from Mapabc.
The problem is not looking at maps. It is the position of the GPS dot is off. You can’t access GPS with http://ditu.google.com/
If I didn’t need to pin point my position on Maps with GPS, it would work just fine as a regular map.
When I recently tried to put the China map into my old Garmin Nuvi 200 I bought in US, I noticed this issue discussed at a forum:
The satellites we all use today for GPS navigation is controlled by US. I guess the data transmitted by satellites can be manipulated by US whenever necessary. So in theory the reading of every GPS device can be controlled by US. This certainly makes Chinese government nervous. They want to use their own GPS navigation satellites. By providing erroneous map data they try to discourage the use of existing GPS platform. Ideally all those random errors can be only perfectly corrected by using the data transmitted from China-made navigation satellites in the future.
No. I don’t think it’s a problem with the Sats at all. China have been using GPS for years. They have them built into cars, and you can buy portable GPS virtually anywhere they sell electronics. I have a Mio I got myself and have been using it for almost 3 years now. It is accurite to a few meters.
I doubt China will launch their own Sats as it is too costly and I don’t really see a need for it. If they need to rely on other means of location service, they can always use the massive cell phone network.
I do really believe the problem lies with Google maps and some Chinese policy. I’m wondering if iPhones sold in China have this problem? That would suck cuz their iPhones are already lacking wifi.
This is not a problem with Google or the GPS satellites. Because the Chinese government fears the military use of the US GPS system, they control all the GPS chips imported into the country. The Chinese government overlays a code that causes all GPS co-ordinates to offset a specific distance from their actual physical location. The government then issues “official” maps that match the GPS offset. This is why satellite images and “official” maps do not line up properly. But approved navigation systems work perfectly well. Because the offset is specific to China, unofficially imported GPS chips, like those in mobile phones, will not properly plot.
I have bought a garmin zumo 550 gps in denmark and the china navigator map from canada.
It did not work here in China because of the off set of approximately 400 meter.
Have tried every thing, downloaded the bin file, talked to garmin, updated my garmin, downloaded maps from the net. Nothing worked.
Then I found http://www.vttown.com
They just wanted type, model and id number of my garmin and 2 days later I got the navigator map and every thing works perfect.
So if you have problems contact vttown.
James: If that’s the case, then why does the satellite view of google maps work perfectly? Does that mean the “hidden” code is built into the satellite part of the maps but not the road part?
No offense but the “military” excuse just doesn’t make sense. Anyone can come here and buy a GPS that works perfectly. So in a sense, any military from any country can buy one. Heck, I can buy one and send it anywhere in the world. Then extract whatever code and apply it to their GPS system.
The more realiatic view on this is just money. You can’t buy GPS from outside China so people will need to buy it in China. Simple as that.
For iPhone,if you want to solve the China maps misalignment issue. Try
In China, the built-in iPhone Maps application is distorted and will
show you a position that is 300-1000m randomly from reality. The
ABCMaps application is to align the maps to the real place.
ABCMaps is Chinese only applcation now. However, it is so easy to use.
So even you can not read Chinese you can use it also. The English
version will come out in the future.
ABCMaps is upgraded to version 1.30, English support added.
Find out where you are really in China. If you travel in China,
sometimes you will be troubled by China maps offset. The ABCMaps application is to align automatically the maps to the real place .
If available in your area, real-time traffic conditions will be
displayed over the road as color-coded lines by click “Traffic” button.
What’s New In Version 1.30
1. English support added
2. Traditional Chinese support added
3. Small bug fix for iOS 3.0
Isn’t ABC maps also providing maps to Google? It seems like they are giving Google wrong (misaligned/offset) maps while pushing their own product without these errors?!
Ok, I’ve tried ABC maps. Works great! Too bad it’s lacking any features but it shows that it is possible. Also shows that the offset is NOT random and it only happen on the default Maps software.
What does this mean? Well it means what I’bebeen saying: that only the google map is affected, on purpose.
I don’t know exactly how ABC Maps re-align the gps coordinates but I know that’s the only thing they did because if you switch between street and sat view, they still don’t overlap exactly. ABC maps simply aligns the gps coordances and put them on the map view. Perhaps they simply use the sat views coordinates for the map view because the sat views are correct in the default map program.
But great start nonetheless. The ads do bug me a little and I honestly would pay money for this if it had more features and remove the ads. I’ve already used it a few times and the gps locations are spot on. Hope there will be more updates to come.
As a Chinese Native, I can confirm these offsets are done on purpose. There are regulations on how maps must be distorted especially for foreign maps providers. Actually GPS in China is quite accurate for GPS navigation software on Android or iPhone, at the cost they do not provide satellite maps. Yes there are many patches that can be found to fix these distortions, mostly in Chinese.
Sounds like they may have used a different geodetic datum transform or method. This is usually done in an effort to reduce position errors in legacy data, but the same mechanism with a synthetic or handmade datum would allow positions to be intentionally obfuscated. If you have access to the datum it is a simple matter to “undo.”
Great post. I am interested to hear more about bitcoin ussage in china
Hey, I live in ex-USSR near the western border, and the same situation is (was) here – in all soviet-time maps (and any recent maps based on them w/o starting from stratch), all the roads near the border and the Baltic sea are not quite matching reality; not mistake-like, but with seemingly systematic, intentional distortions on how their position is skewed by 0.5-2 km and the turns/crossings tend to be put in a misleading way.
That’s how closed societies tend to do things, but it’s really obsolete now as any random civilian gan get decent uncensored sat-maps and accurate geopositioning.
You should have some basic knowledge on cartography before posting this and commenting on this.
The mismatch between satellite map and street map is just because they use different coordinate system.
Generally speaking, the earth is a 3D object while the map is 2D. So we have to choose a mapping function do map a 3D coordinate (spherical coordinates) to a 2D coordinate (x,y). There isn’t a perfect global mapping so different countries choose their own mapping. In China, we use Krasovski system(Beijing 54) and then moved to Xi’an 80 system. All the street maps made in China are based on this system. However, the satellite map is made outside China by a WGS84 system. So you will find some mismatch between the two systems. You can also find the mismatch in Russia and many other countries which made their fundamental geographic information with another system.
Also, there is a law that you can’t use a common coordinate system (like WGS84) to make map in China.
Every map provider (including GPS manufacturer) has an encryption key. All of the services provided by this provider should be on a map transformed by this encryption key. For GPS, because both map and your current location are transformed by the same key, you won’t have any problem using it. But if you want to overlay map from one provider with one from another provider, because all their keys and transforms are different, result will be meaningless.
Hi there great post and one of the best explanations I’ve found in the web so far. What I’m still puzzled about is why this is the case. Is it because google maps somehow collaborates with the Chinese government. Surely the GPS is accurate as it comes from US Satellites so why don’t google just use maps that correspond with that and cut the Chinese out of the equation. Also many posts state that satellite view is correct but the street view is incorrect. I’ve found this to be the other way round on google maps for iPad (quite new I believe). On my iphone it seems to be correct in both views on apple and google maps.
Now I dare say there won’t be a logical answer to this but Why Oh Why! This is nonsensical if the US military wanted to bomb China they won’t be relying on google maps. Either this is completely paranoid and illogical (wouldn’t surprise me at all in China) o there must b some commercial reason behind this that benefits Chinese companies. Any explanation much appreciated particularly in regard to the google collaboration but. Cheers
Okay slight correction. Google maps on my iPhone also displaying wrong location in Satellite view. Apple Maps perfect. I guess any potential wrongdoer should just get an iPhone to beat China’s paranoid mapping bureau
ditu.google.cn works, but maps.google.com does not. Google could fix the problem easily by using the ditu data instead of the maps data.