View source for Restrictions on geographic data in China

{{short description|Restrictions on using GPS in China}}
{{Use dmy dates|date=August 2015}}
Under Chinese law, the use of [[Geographic information systems in China|geographic information in the People's Republic of China]] is restricted to entities that have special authorization from the administrative department for surveying and mapping under the [[State Council of the People's Republic of China|State Council]].<ref name="law">{{cite web|title=Surveying and Mapping Law of the People's Republic of China|url=http://en.nasg.gov.cn/article/Lawsandregulations/201312/20131200005471.shtml|publisher=National Administration of Surveying, Mapping and Geoinformation of China|access-date=7 April 2015|archive-url=https://web.archive.org/web/20170525200020/http://en.nasg.gov.cn/article/Lawsandregulations/201312/20131200005471.shtml|archive-date=25 May 2017|url-status=dead}}</ref> Consequences of the restriction include fines for unauthorized surveys, lack of [[geotagging]] information on many cameras when the [[Global Positioning System|GPS]] chip detects a location within China, and incorrect alignment of street maps with satellite maps in various applications.<ref>{{cite conference|author1=Rabaza Bergua, Carlos S.|author2=López-de-Larrínzar-Galdámez, Juan|author3=Salvador Suárez, Iván|author4=Usón Montesinos, Miguel|author5=Muro Medrano, Pedro R.|title=Restricciones al trabajo con información geográfica online en China|url=http://www.idee.es/resources/presentaciones/JIIDE13/miercoles/15_restriscciones_IG_MapasEnChina_presentacion.pdf|conference=IV Jornadas Ibéricas de Infraestructuras de Datos Espaciales|publisher=JIIDE 2013|location=Universidad de Castilla-La Mancha, Campus Tecnológico Fábrica de Armas, Toledo|date=13 November 2013}}</ref>

Chinese lawmakers said that these restrictions are to "safeguard the security of China's geographic information".<ref name="Reuters-2017">{{Cite news|date=2017-04-27|title=China revises mapping law to bolster territorial claims|language=en|work=Reuters|url=https://www.reuters.com/article/us-china-lawmaking-idUSKBN17T1S4|access-date=2021-02-14}}</ref> Song Chaozhi, an official of the [[State Bureau of Surveying and Mapping]], said "foreign organizations who wish to carry out mapping or surveying work within China must make clear that they will not touch upon state secrets or endanger state security".<ref name="Reuters-2017" /> Critics outside of China point out that the laws close critical sectors of the Chinese economy to foreign companies, and assist with cracking down on dissent.<ref name="Reuters-2017" />

== Legislation ==

=== Surveying ===
According to articles 7, 26, 40 and 42 of the ''Surveying and Mapping Law of the People's Republic of China'', private surveying and mapping activities have been illegal in mainland China since 2002. The law prohibits:<ref>{{cite wikisource |wslink=中华人民共和国测绘法 |title=中华人民共和国测绘法 |date=1992 |wslanguage=zh}}</ref>

{{Blockquote
|publishing, without authorization, significant geographic information and data concerning the territorial air, land and waters, as well as other sea areas under the jurisdiction of the People's Republic of China.
|author=The National Administration of Surveying, Mapping and Geoinformation of China
|title=Surveying and Mapping Law of the People's Republic of China
}}

Article 1 says:

{{Blockquote
|This Law is enacted to strengthen the administration of the surveying and mapping undertaking, promote its development and ensure that it renders service to development of the national economy, the building up of national defence, and progress of the society.<ref name="en.nasg.gov.cn">{{Cite web|url=http://en.nasg.gov.cn/article/Lawsandregulations/201312/20131200005471.shtml|title=Surveying and Mapping Law of the People's Republic of China— National Administration of Surveying, Mapping and Geoinformation|website=en.nasg.gov.cn|access-date=2018-02-27|quote=Articles 7, 26, 40 and 42|archive-url=https://web.archive.org/web/20170525200020/http://en.nasg.gov.cn/article/Lawsandregulations/201312/20131200005471.shtml|archive-date=25 May 2017|url-status=dead}}</ref>
}}

Fines range from 10,000 to 500,000 [[Renminbi|CNY]] (US${{To USD|10000|CHN|round=yes}}–{{To USD|500000|CHN|round=yes}}). Foreign individuals or organizations that wish to conduct surveying must form a Chinese-foreign joint venture.<ref name="law" />

Between 2006 and 2011, the authorities pursued around 40 illegal cases of mapping and surveying.<ref>{{cite journal|last1=Hvistendahl|first1=M.|title=Foreigners Run Afoul of China's Tightening Secrecy Rules|journal=Science|date=24 January 2013|volume=339|issue=6118|pages=384–385|doi=10.1126/science.339.6118.384|pmid=23349263|bibcode=2013Sci...339..384H}}</ref> The media has reported on other cases of unlawful surveys:
* March 7, 2007 — Japanese and Korean scholars fined; joint-venture Weihai hired foreign surveyors without approval from the government<ref>{{cite news|last1=Dingding|first1=Xin|title=Unlawful surveys to be dealt severely|url=http://www.chinadaily.com.cn/china/2007-03/07/content_821274.htm|publisher=[[China Daily]]|date=7 March 2007}}</ref>
* March 25, 2008 — China's [[State Bureau of Surveying and Mapping]] cracks down on some of the 10,000 websites that publish maps in China, most without authorization.<ref>{{cite news|last1=Liang|first1=Yan|title=China cracks down on illegal online map services to protect state security|url=http://news.xinhuanet.com/english/2008-03/25/content_7858467.htm|archive-url=https://web.archive.org/web/20080330050203/http://news.xinhuanet.com/english/2008-03/25/content_7858467.htm|url-status=dead|archive-date=30 March 2008|agency=[[Xinhua News Agency]]|date=25 March 2008|location=Beijing}}</ref>
* January 6, 2009 — Chinese authorities fine UK students for "illegal map-making activities".<ref>{{cite news|url=http://www.chinapost.com.tw/china/national-news/2009/01/06/190764/China-fines.htm|title=China fines UK students for 'illegal map-making'|date=6 January 2009|archive-url=https://web.archive.org/web/20100616150006/http://www.chinapost.com.tw/china/national-news/2009/01/06/190764/China-fines.htm|archive-date=2010-06-16|agency=AFP}}</ref>
* 2010 — Chinese authorities to crack down on the unregistered or illegal among 42,000 online map providers, targeting incorrect information and leaks of sensitive information involving state secrets. New standards require all Internet map providers to keep servers storing map data inside China.<ref>{{cite news|last1=Wang|first1=Guanqun|title=China issues new rules on Internet map publishing|url=http://news.xinhuanet.com/english2010/china/2010-05/19/c_13302696.htm|archive-url=https://web.archive.org/web/20100523060424/http://news.xinhuanet.com/english2010/china/2010-05/19/c_13302696.htm|url-status=dead|archive-date=23 May 2010|agency=Xinhua News Agency|date=19 May 2010}}</ref>
* March 14, 2014 — Coca-Cola is accused of illegal mapping.<ref name="motherboard">{{cite web|last1=Pasternack|first1=Alex|title=If You're a Foreigner Using GPS in China, You Could Be a Spy|url=https://motherboard.vice.com/en_us/article/3ddmzv/if-youre-a-foreigner-in-china-it-is-illegal-to-use-gps|publisher=[[Vice (magazine)|Vice]]|date=14 March 2013}}</ref>

As a consequence, major digital camera manufacturers including Panasonic, Leica, FujiFilm, Nikon and Samsung restrict location information within China.<ref>{{cite web|last=Doctorow |first=Cory |author-link=Cory Doctorow |title=Why your camera's GPS won't work in China (maybe) |url=http://ogleearth.com/2012/05/why-do-panasonic-leica-fujifilm-samsung-and-nikon-censor-their-gps-cameras/ |date=23 May 2015 |publisher=[[Boing Boing]] |archive-url=https://web.archive.org/web/20150525154414/http://ogleearth.com/2012/05/why-do-panasonic-leica-fujifilm-samsung-and-nikon-censor-their-gps-cameras/ |archive-date=25 May 2015 }}</ref>

[[OpenStreetMap]], the [[crowdsourcing|crowdsourced]] project to assemble a map of the world, advises that "private surveying and mapping activities are illegal in China".<ref name="osm-pjcn-legal">{{cite web|title=Legality|url=https://wiki.openstreetmap.org/wiki/WikiProject_China#Legality|website=Project China|publisher=[[OpenStreetMap]]|access-date=7 April 2015}}</ref>

=== Map content ===
{{Wikisourcelang|zh|分类:中华人民共和国地图|Category:PRC maps}}

Chinese law and regulations also rule on the contents of any published map:
* The "Certain Provisions on the Display of Public Map Content" ({{zh|s=公开地图内容表示若干规定|links=no}}) of 2003 by the [[Bureau of Surveying and Mapping]] (BSM) prohibits the representation of sensitive information such as airports (except those specially listed), military bases, and waterway depths. It also describes the handling and naming of disputed territories and former Qing territories ceded to Russia.<ref>{{cite wikisource |wslink=公开地图内容表示若干规定 |date=2003 |wslanguage=zh}}</ref>
* The "Supplementary rules on the content presentation of public maps, trial version" ({{zh|s=公开地图内容表示补充规定（试行）|links=no}}) of 2009 from the BSM additionally prohibits, among other things:<ref>{{cite wikisource |wslink=公开地图内容表示补充规定（试行） |title=公开地图内容表示补充规定（试行） |date=2009 |wslanguage=zh}}</ref>
** Locations having a precision of finer than {{convert|50|m|yd}} and the use of grids finer than {{convert|100|m|yd}} for elevation data.
** Showing the locations of key infrastructure (power, dams, weather stations) and public safety installations (prisons, mandatory drug rehab facilities).
** Showing the internal structures of airports and ferry ports.
** Showing the weight and height limits of bridges, roads, and tunnels; showing the material of roads.
* The "Map management regulation" ({{zh|地图管理条例|links=no}}) of 2015 from the State Council mandates that all Internet maps must be stored in mainland China, among other rules about national security. The law also details punishments, some of which criminal, for violations.<ref>{{cite wikisource |wslink=地图管理条例 |title=地图管理条例 |date=2015 |wslanguage=zh}}</ref>

In 2016, a large-scale search by Chinese law enforcement found 253 types of problematic paper maps and 1000 problematic online map websites, most pertaining to the depiction of [[Taiwan]] and [[9-dash line]].<ref>{{cite web |trans-title=What problems do "problematic maps" bring?|title="问题地图"会带来哪些问题？ |url=http://www.xinhuanet.com/mil/2017-02/15/c_129480599.htm |website=新华网 |language=zh-Hans-CN}}</ref>

== Coordinate systems ==
{{geodesy}}
[[File:PRcoords Cheatsheet.pdf|220px|thumb|right|JavaScript implementation of coordinate "processing" methods used in China]]

Chinese regulations require that approved map service providers in China use a specific coordinate system, called GCJ-02 (colloquially ''Mars Coordinates''). [[Baidu Maps]] uses yet another coordinate system - BD-09,<ref name="bd-09">{{cite web|title=Coordinate conversion|url=http://developer.baidu.com/map/jsdemo.htm#a5_1|publisher=[[Baidu Maps]]|access-date=7 April 2015|language=zh}}</ref><ref name="baidu-map-api-coordinate-conversion"/> which seems to be based on GCJ-02.<ref name="caijun"/>

{{Blockquote
|Technical spatial processing must be applied to electronic navigational maps prior to publication, sales, redistribution, and usage.
|title=GB 20263―2006 "[[s:zh:GB 20263-2006 导航电子地图安全处理技术基本要求|Basic security processes for electronic navigational maps]]", 4.1
}}

=== GCJ-02 ===
'''GCJ-02''' ({{zh|s=地形图非线性保密处理算法|p=Dìxíng tú fēixiànxìng bǎomì chǔlǐ suànfǎ|l=Topographic map non-linear confidentiality algorithm}})<ref name="cpc_chengming" /> is a [[geodetic datum]] used by the Chinese [[State Bureau of Surveying and Mapping]], and based on [[WGS-84]].<ref>{{cite web|title=Quickstart|url=https://angular-ui.github.io/angular-google-maps/#!/use |website=Google Maps for AngularJS |access-date=7 April 2015 }}</ref> It uses an obfuscation algorithm<ref>{{cite web |url=http://m.it168.com/article_1778861.html |title=手机地理轨迹取证步骤大解密 |publisher=IT168 }}</ref> which adds apparently random offsets to both the latitude and longitude, with the alleged goal of improving national security.<ref name="caijun" /><ref>{{cite web|url=http://www.site-digger.com/html/articles/20140115/72.html |title=国内常见的电子地图坐标介绍 |publisher=鲲鹏Web数据抓取 }}</ref> There is a license fee associated with using this mandatory algorithm in China.<ref name="cpc_chengming"/>

A marker with GCJ-02 coordinates will be displayed at the correct location on a GCJ-02 map. However, the offsets can result in a 100–700 meter error from the actual location if a WGS-84 marker (such as a GPS location) is placed on a GCJ-02 map, or vice versa. The [[Google Maps]] street map is offset by 50–500 meters from its satellite imagery.<ref name=motherboard /><ref>{{cite web|title=Google.com hybrid map of The Bund|url=https://www.google.com/maps/place/The+Bund/@31.2417003,121.49003,1096m/data=!3m1!1e3!4m2!3m1!1s0x35b270578b874861:0x4d56fbed10d1af64|access-date=7 April 2015}}</ref> [[Yahoo! Maps]] also displayed the street map without major errors when compared to the satellite imagery.<ref name="yahoo-map">{{cite web|title=Yahoo! Map of The Bund|url=https://maps.yahoo.com/place/?lat=31.24175591400924&lon=121.49212718009949&q=shanghai&bb=31.24629644%2C121.48394644%2C31.23721516%2C121.50030792&addr=shanghai|access-date=7 April 2015}}</ref> MapQuest overlays OpenStreetMap data perfectly as well.<ref>{{cite web|title=MapQuest map of The Bund|url=http://mapq.st/1C9QlaP|access-date=7 April 2015}}{{Dead link|date=March 2020 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

Despite the secrecy surrounding the GCJ-02 obfuscation, several open-source projects exist that provide conversions between GCJ-02 and WGS-84, for languages including [[C Sharp (programming language)|C#]],<ref name=leak>{{cite web|title=EvilTransform.cs|url=https://on4wp7.codeplex.com/SourceControl/changeset/view/21455#EvilTransform.cs|date=2 February 2013}}</ref> [[C (programming language)|C]], [[Go (programming language)|Go]], [[Java (programming language)|Java]], [[JavaScript]], [[PHP]],<ref name=evil-gh>{{cite web|last=Lee |first=Googol |title=Transform coordinates between Earth (WGS-84) and Mars in China (GCJ-02) |website=[[GitHub]] |date=14 October 2021 |url=https://github.com/googollee/eviltransform }}</ref> [[Python (programming language)|Python]],<ref>{{cite web|title=China GPS offset problem |url=http://blog.snapdragon.cc/2013/07/17/china-gps-offset-problem/ |website=SnapDragon Blog }}</ref> [[R (programming language)|R]],<ref name=caijun /> and [[Ruby (programming language)|Ruby]].<ref>{{cite web |title=MarsGeo |url=https://www.omniref.com/ruby/gems/mars_geo/0.0.1 |publisher=Omniref |archive-url=https://web.archive.org/web/20150416161655/https://www.omniref.com/ruby/gems/mars_geo/0.0.1 |archive-date=16 April 2015 |url-status=dead |df=dmy-all}}</ref><ref>{{cite web |title=EvilTransform Ruby gem |url=https://rubygems.org/gems/evil_transform/versions/0.0.1}}</ref> They appear to be based on leaked code for the WGS to GCJ part.<ref>{{cite web|last=Feng |first=Zili |title=ChinaMapDeviation|website=[[GitHub]] |url=https://github.com/maxime/ChinaMapDeviation/issues/1#issuecomment-89987212 |archive-url=https://web.archive.org/web/20150407111031/https://github.com/maxime/ChinaMapDeviation/issues/1 |archive-date=7 April 2015 |date=6 April 2015}}</ref> Other solutions to the conversion involve interpolating coordinates based on [[regression analysis|regression]] from a data set of Google China and satellite imagery coordinates.<ref name=guilbot-reg>{{cite web |last=Guilbot |first=Maxime |title=ChinaMapDeviation |website=[[GitHub]] |url=https://github.com/maxime/ChinaMapDeviation |date=28 May 2013}}</ref> An attempt by Wu Yongzheng using [[fast Fourier transform]] analysis gave a result much like the leaked code.<ref name="wu-regression">{{cite web |last=Wu| first=Yongzheng |title=The Deviation of China Map as a Regression Problem |url=https://wuyongzheng.github.io/china-map-deviation/paper.html |website=GitHub Pages |access-date=1 February 2016}}</ref>

From the leaked code,<ref name=leak/><ref>{{Cite web |title=EvilTransform |website=[[GitHub]] |url=https://github.com/Leask/EvilTransform}}</ref> GCJ-02 uses parameters from the [[SK-42 reference system]]. The parameters were used to calculate lengths of one degree of [[Latitude#Length of a degree of latitude|latitude]] and [[Longitude#Length of a degree of longitude|longitude]], so that offsets in meters previously calculated can be converted to degrees for the WGS-84 input coordinates.

=== BD-09 ===
{{Main article|Baidu Maps#Coordinate system}}
BD-09 is a geographic coordinate system used by [[Baidu Maps]], adding further obfuscation to GCJ-02 "to better protect users' privacy".<ref>{{cite web|url=http://developer.baidu.com/map/question.htm#qa0023 |title=Baidu LBS Open Platform FAQ |publisher=Baidu Developer |access-date=2016-12-19}}</ref><ref name="baidu-map-api-coordinate-conversion">{{cite web|title=坐标转换API|trans-title=Coordinate Conversion API|archive-url=https://archive.today/20170328095201/http://developer.baidu.com/map/changeposition.htm|archive-date=2017-03-28|url=http://developer.baidu.com/map/changeposition.htm|website=developer.baidu.com/map|publisher=Baidu|language=zh}}</ref> Baidu provides an API call to convert from Google or GPS (WGS-84), GCJ-02, BD-09, {{ill|MapBar|lt=|zh|图吧}} or {{ill|51ditu|lt=|zh|灵图}} coordinates into Baidu or GCJ-02 coordinates.<ref name="baidu-api-manual">{{cite web|url=http://lbsyun.baidu.com/index.php?title=webapi/guide/changeposition|title=WEB 服务 API – 坐标转换服务 |publisher=百度地图开放平台|language=zh|date=2014-03-06|access-date=2019-03-23 |quote=根据相关法律规定，不支持将任何一种坐标系坐标转换为WGS84类型。}}</ref><ref name="bd-09" /> As required by local law,<ref name="baidu-api-manual"/> there is no API to convert into WGS-84, but open source implementations in R<ref name="caijun">{{cite web|title=A package for geocoding, reverse geocoding and coordinate transformations between WGS-84, GCJ-02 and BD-09 coordinate systems|website=[[GitHub]]|url=https://github.com/caijun/geoChina|date=15 February 2014}}</ref> and various other languages<ref name=evil-gh/> exist.

=== Reverse transformation ===
As the actual algorithm is now available in open source form (see above), the text below is obsolete.

GCJ-02 appears to use multiple high-frequency noises of the form <math>20n \sin{}(180 k \times lat_{rad})</math>, effectively generating a [[transcendental equation]] and thus eliminating analytical solutions.{{citation needed|date=February 2019}} However, the open-source "reverse" transformations make use of the properties of GCJ-02 that the transformed coordinates are not too far from WGS-84 and are mostly monotonic related to corresponding WGS-84 coordinates:<ref name=fengzee /><ref name=caijun />

<syntaxhighlight lang="python">
from typing import Callable

# Represent coordinates with complex numbers for simplicity
coords = complex
# Coords-to-coords function
C2C = Callable[[coords], coords]

def rev_transform_rough(bad: coords, worsen: C2C) -> coords:
    """Roughly reverse the ``worsen`` transformation.

    Since ``bad = worsen(good)`` is close to ``good``,
    ``worsen(bad) - bad`` can be used to approximate ``bad - good``.

    First seen in eviltransform.
    """
    return bad - (worsen(bad) - bad)

def rev_transform(bad: coords, worsen: C2C) -> coords:
    """More precisely reverse the ``worsen`` transformation.

    Similar to ``rev_transform_rough``,
    ``worsen(a) - worsen(b)`` can be used to approximate ``a - b``.

    First seen in geoChina/R/cst.R (caijun 2014).
    Iteration-only version (without rough initialization) has been known
    since fengzee-me/ChinaMapShift (November 2013).
    """
    eps = 1e-6
    wgs = bad
    improvement = 99 + 99j  # dummy value

    while abs(improvement) > eps:
        improvement = worsen(wgs) - bad
        wgs = wgs - improvement
    return wgs
</syntaxhighlight>

The rough method is reported to give some 1~2 meter accuracy for wgs2gcj,<ref name=evil-gh/> while the exact ([[fixed point iteration]]) method is able to get "centimeter accuracy" in two calls to the forward function.{{NoteTag|1=i.e. <code>wgs -= worsen(wgs) - bad</code> done twice, with <code>wgs</code> initialized as <code>bad</code> so that the first iteration is equivalent to a rough pass.}}<ref name="gh_86ae326">{{cite web|author1=bewantbe|title=make gcj2wgs_exact() much faster, by using fixed…|url=https://github.com/bewantbe/eviltransform/commit/86ae326|website=GitHub|access-date=29 February 2016}}</ref><ref name=fengzee>{{cite web|language=zh|title=中国地图偏移算法|url=http://wenku.baidu.com/view/9a53e4edd5bbfd0a795673c6.html|archive-url=https://web.archive.org/web/20200324031931/https://wenku.baidu.com/view/9a53e4edd5bbfd0a795673c6.html|archive-date=2020-03-24}} [https://gist.github.com/anonymous/e7c6f67555099180ce1ae8da4ba2c513 Alt URL]</ref> The BD-to-GCJ code works in a manner much like the rough method, except that it removes the explicitly-applied constant shift of ~20 seconds of arc on both coordinates first and works in polar coordinates like the forward function does.<ref name=caijun />

The establishment of working conversion methods both ways largely renders obsolete datasets for deviations mentioned below.<ref name="Corr"/>

== GPS shift problem ==
[[File:Google.com Maps in China coordinate system misalignment.png|thumb|right|Google Maps displays satellite imagery using the WGS-84 coordinate system, and street maps using the GCJ-02 datum]]

The China GPS shift (or offset) problem is a class of issues stemming from the difference between the [[#GCJ-02|GCJ-02]] and [[WGS-84]] [[geodetic datum|datum]]s. [[Global Positioning System]] coordinates are expressed using the WGS-84 standard and when plotted on street maps of China that follow the GCJ-02 coordinates, they appear off by a large and variable amount (often over {{convert|500|m|disp=sqbr}}). Authorized providers of location-based services and digital maps (such as [[AutoNavi]], NavInfo, or [[Apple Maps]]<ref>{{cite web|title=Gaia GPS & China's GPS Restrictions |url=https://blog.gaiagps.com/gaia-gps-chinas-gps-restrictions/ |date=8 February 2016 }}</ref>) must purchase a "shift correction" algorithm that enables plotting GPS locations correctly on the map.<ref name="Corr">{{cite web|last=Feng |first=Zili |title=The government charges Chinese companies for the "shift correction" feature |url=https://github.com/maxime/ChinaMapDeviation/issues/1#issuecomment-90462107 |website=[[GitHub]] |date=7 April 2015}}</ref> Satellite imagery and user-contributed street map data sets, such as those from [[OpenStreetMap]] also display correctly because they have been collected using GPS devices (albeit technically illegally).

Some map providers, such as [[Here (company)|Here]], choose to also offset their satellite imagery layer to match the GCJ-02 street map.<ref>{{cite web|author1=Monument to the People's Heroes|author-link1=Monument to the People's Heroes (Shanghai)|title=Nokia Here street map and satellite map both use GCJ-02 coordinates|url=https://www.here.com/?map=31.24427,121.48695,18|access-date=8 April 2015}}</ref>

Google has worked with Chinese location-based service provider [[AutoNavi]] since 2006 to source its maps in China.<ref name=bloomberg>{{cite news|last1=Lee|first1=Mark|title=Apple Shares Google China Map Partner in Win for AutoNavi: Tech|newspaper=Bloomberg.com|url=https://www.bloomberg.com/news/articles/2012-07-05/apple-shares-google-china-map-partner-in-win-for-autonavi|publisher=Bloomberg|date=6 July 2012}}</ref>
Google uses GCJ-02 data for the street map, but does not shift the satellite imagery layer, which continues to use WGS-84 coordinates,<ref>{{cite web|author1=Monument to the People's Heroes|author-link1=Monument to the People's Heroes (Shanghai)|title=Google.com satellite imagery uses WGS-84 coordinates|url=https://www.google.com/maps/@31.2423,121.4914,267m/data=!3m1!1e3|access-date=8 April 2015}}</ref> with the benefit that WGS-84 positions can still be overlaid correctly on the satellite image (but not the street map). Google Earth also uses WGS-84 to display the satellite imagery.<ref>{{cite web|title=Could you please correct the offset in China due to GCJ-02 coordinate?|url=https://productforums.google.com/forum/#!topic/earth/4PPOyz5YA8g|website=Google Earth|publisher=Google Product Forums|date=6 April 2014}}</ref>

Overlaying GPS tracks on [[Google Maps]] and any street maps sourced from Google.com via its API, will lead to a similar display offset problem, because GPS tracks use WGS-84, and Google Maps uses GCJ-02. The issue has been reported numerous times on the Google Product Forums since 2009,<ref>{{cite web|title=OFFSET MAPPING ISSUE IN CHINA|url=https://productforums.google.com/d/msg/maps/zVmRao1Im3w/bvk-n_jgPvQJ|website=Google Product Forums|date=5 March 2012}}</ref> with 3rd party applications emerging to fix it.<ref>{{cite web|title=ABCMaps application to fix the China GPS offset|url=https://productforums.google.com/d/msg/maps/4betfwupNjE/IEUe3x5oPpAJ|date=24 July 2010}}</ref> Data sets with offsets for large lists of Chinese cities existed for sale.<ref>{{cite web|last1=Pasden|first1=John|title=A More Complete iOS Solution to the China GPS Offset Problem|url=http://www.sinosplice.com/life/archives/2013/07/16/a-more-complete-ios-solution-to-the-china-gps-offset-problem|date=23 December 2014}}</ref> The problem was observed as early as 2008, and the causes were unclear, with (misguided) speculation that imported GPS chips were tampered with code that caused incorrect reporting of coordinates.<ref>{{cite web|last1=Wang|first1=Jian Shuo|title=All Maps in China are Transformed|url=http://home.wangjianshuo.com/archives/20081109_all_maps_in_china_are_transformed.htm|archive-url=https://web.archive.org/web/20140116215242/http://home.wangjianshuo.com/archives/20081109_all_maps_in_china_are_transformed.htm|archive-date=16 January 2014}}</ref>

=== Hong Kong and Macau ===
Under [[One Country Two Systems]], legislation in mainland China does not apply in [[Hong Kong]] and [[Macau]] SARs and there are no similar restrictions in the SARs.{{citation needed|date=August 2023}} Therefore, the GPS shift problem does not apply. However, at the border between the SARs and mainland China, the data shown by online maps, such as Google Maps,<ref>{{cite web|url=https://www.google.com.hk/maps/@22.5274336,114.0849645,14z |title=Google Maps near Hong Kong-Shenzhen border |publisher=Google Maps |access-date=2016-12-19}}</ref> are broken where the shifted data and correct data overlap. This poses problems to users travelling across the border,{{clarify|date=August 2023|reason=What problems do they experience?}} especially visitors unaware of the issue.{{citation needed|date=August 2023}}

==See also==
* [[Geographic information systems in China]]
* [[Restrictions on geographic data in South Korea]]

==Notes==
{{notefoot}}

== References ==
{{reflist|refs=
<ref name="cpc_chengming">{{cite web|title=科研要为祖国和人民服务――记中国测绘科学研究院地图学与地理信息系统研究所党支部书记、所长李成名| trans-title=Scientific Research Should Serve the Motherland and the People: On Li Chengming, Secretary of the Party Branch and Director of the Institute of Cartography and Geographic Information System, China Academy of Surveying and Mapping Sciences |url=http://cxzy.people.com.cn/GB/196034/14908095.html |website=中国共产党新闻网 |publisher=人民网（创先争优）|access-date=2017-03-30 |archive-url=https://archive.today/20110804185923/http://cxzy.people.com.cn/GB/196034/14908095.html |archive-date=2011-08-04 |language=zh-CN 
|quote=李成名怀着“要为国家做点什么，要为百姓做点什么”的信念，带领团队研制出地形图非线性保密处理算法，开发出“新地图”系列软件，有效解决了测绘成果保密与民用的两难问题。 [...] 然而，李成名及其团队作出决定：将“新地图”软件以只收取成本费用甚至免费的方式提供给各个城市。
|trans-quote=LCM believed that he had to "do something for the state and the people". He led his team in the R&D of a topographic map non-linear confidentiality algorithm and a "new map" software suite, thereby effectively solving the conflict of confidentiality and civilian use of survey results. However, Li Chengwan and his team decided to provide the "new map" software to cities at cost or even for free.}}</ref>
}}

{{Censorship in China}}

[[Category:Censorship in China]]
[[Category:Internet censorship in China]]
[[Category:Web mapping]]
[[Category:Geographic data and information regulation]]