Google Maps

Google Maps

File:Google Maps directions.png Screenshot of Google Maps showing a route from San Francisco to Los Angeles on Interstate 5.
Type of site	Web mapping
Available in	Multilingual
Owner	Google
Created by	Google
URL	maps.google.com
Registration	No

Google Maps (formerly Google Local) is a web mapping service application and technology provided by Google, free (for non-commercial use), that powers many map-based services, including the Google Maps website, Google Ride Finder, Google Transit, and maps embedded on third-party websites via the Google Maps API. It offers street maps, a route planner for traveling by foot, car, or public transport and an urban business locator for numerous countries around the world. According to one of its creators (Lars Rasmussen), Google Maps is "a way of organizing the world's information geographically".

Google Maps uses a close variant of the Mercator projection, so it cannot show areas around the poles. A related product is Google Earth, a stand-alone program which offers more globe-viewing features, including showing polar areas.

Satellite view

Google Maps provides high-resolution satellite images for most urban areas in the United States (including Hawaii, Alaska, Puerto Rico, and the U.S. Virgin Islands), Canada, and the United Kingdom, as well as parts of Australia and many other countries. The high-resolution imagery has been used by Google Maps to cover all of Egypt's Nile Valley, Sahara desert and Sinai. Google Maps also covers many cities in the English speaking areas. However, Google Maps is not solely an English maps service, since its service is intended to cover the world.

Various governments have complained about the potential for terrorists to use the satellite images in planning attacks. Google has blurred some areas for security (mostly in the United States), including the U.S. Naval Observatory area (where the official residence of the Vice President is located), and previously the United States Capitol and the White House. Other well-known government installations, including Area 51 in the Nevada desert, are visible. Not all areas on satellite images are covered in the same resolution; less populated areas usually get less detail. Some areas may be obscured by patches of clouds.

With the introduction of an easily pannable and searchable mapping and satellite imagery tool, Google's mapping engine prompted a surge of interest in satellite imagery. Sites were established which feature satellite images of interesting natural and man-made landmarks, including such novelties as "large type" writing visible in the imagery, as well as famous stadia and unique geological formations. As of November 2008, the U.S. National Weather Service also now uses Google Maps within its local weather forecasts, showing the 5 x 5.

Although Google uses the word satellite, most of the high-resolution imagery is aerial photography taken from aircraft rather than from satellites.

Directions

Google Maps directions work

• Contiguously on the African mainland, with the exception of Egypt, Lesotho and the Spanish cities of Ceuta and Melilla
• Contiguously in Europe, the Middle East and South Asia: Andorra, Albania, Armenia, Austria, Azerbaijan, Bangladesh, Belgium, Belarus, Bulgaria, Croatia, Czech Republic, Denmark (excluding the Faroe Islands), Estonia, France, Finland, Germany, Greece, Gibraltar, Hungary, India, Iran, Ireland, Italy, Kazakhstan, Kyrgyzstan, Latvia, Liechtenstein, Lithuania, Luxembourg, FYR Macedonia, Moldova, Monaco, Montenegro, Nepal, The Netherlands, Norway, Pakistan, Poland, Portugal (excluding the Azores and Madeira), Romania, San Marino, Slovakia, Slovenia, Serbia, Spain (including the Canary Islands but excluding Ceuta and Melilla), Sweden, Switzerland, Tajikistan, Turkey, Turkmenistan, Ukraine, United Kingdom Uzbekistan, and the Vatican City
• Contiguously in North America: Canada and the United States
• Contiguously in South America: Argentina, Bolivia, Brazil, Chile, Paraguay and Peru
• Contiguously in Southeast Asia: Cambodia, Laos, Singapore, peninsular Malaysia, Thailand and Vietnam
• In certain noncontiguous countries and regions: Australia, China, Comoros, Egypt, Hawaii, Hispaniola (the Dominican Republic and Haiti), Hong Kong, Iceland, Indonesia (Bali, Java, Madura and Sumatra only), Israel (and parts of the West Bank), Jamaica, Japan, Jordan, South Korea, Lebanon, Macau, Madagascar, Malta, Mauritius, New Zealand, Puerto Rico, Réunion, Russia (Moscow area only), Sabah, Sarawak, Seychelles, Sri Lanka, Taiwan, and the US Virgin Islands.

Implementation

Like many other Google web applications, Google Maps uses JavaScript extensively. As the user drags the map, the grid squares are downloaded from the server and inserted into the page. When a user searches for a business, the results are downloaded in the background for insertion into the side panel and map; the page is not reloaded. Locations are drawn dynamically by positioning a red pin (composed of several partially-transparent PNGs) on top of the map images.

A hidden IFrame with form submission is used because it preserves browser history. The site also uses JSON for data transfer rather than XML, for performance reasons. These techniques both fall under the broad Ajax umbrella.

Extensibility and customization

As Google Maps is coded almost entirely in JavaScript and XML, some end users have reverse-engineered the tool and produced client-side scripts and server-side hooks which allowed a user or website to introduce expanded or customized features into the Google Maps interface.

Using the core engine and the map/satellite images hosted by Google, such tools can introduce custom location icons, location coordinates and metadata, and even custom map image sources into the Google Maps interface. The script-insertion tool Greasemonkey provides a large number of client-side scripts to customize Google Maps data.

Combinations with photo sharing websites, such as Flickr, are used to create "memory maps". Using copies of the Keyhole satellite photos, users have taken advantage of image annotation features to provide personal histories and information regarding particular points of the area.

Google Maps API

Google launched the Google Maps API in June 2005 to allow developers to integrate Google Maps into their websites. It is a free service, and currently does not contain ads, but Google states in their terms of use that they reserve the right to display ads in the future.

By using the Google Maps API, it is possible to embed Google Maps site into an external website, on to which site specific data can be overlaid. Although initially only a JavaScript API, the Maps API has since expanded to include an API for Adobe Flash applications, a service for retrieving static map images, and web services for performing geocoding, generating driving directions, and obtaining elevation profiles. Over 350,000 web sites use the Google Maps API, making it the most heavily used web application development API.

The Google Maps API is free for commercial use providing that the site on which it is being used is publicly accessible and does not charge for access. Sites that do not meet these requirements can purchase Google Maps API Premier.

The success of the Google Maps API has spawned a number of competing alternatives, including the Yahoo! Maps API, Bing Maps Platform, MapQuest Development Platform, and OpenLayers.

Google Maps for Mobile

In 2006, Google introduced a Java application called Google Maps for Mobile, intended to run on any Java-based phone or mobile device. Many of the web-based site's features are provided in the application.

On November 28, 2007, Google Maps for Mobile 2.0 was released. It introduced a GPS-like location service that does not require a GPS receiver. The "my location" feature works by utilizing the GPS location of the mobile device, if it is available. This information is supplemented by the software determining the nearest wireless networks and cell sites. The software then looks up the location of the cell site using a database of known wireless networks and cell sites. The Cell-site location method is used by triangulating the different signal strengths from different cell transmiters and then using their location property (retrieved from the online cell site database) to aid My Location in determining the user's current location. Wireless network location method is calculated by discovering the nearby WiFi hotspots and using their location property (retrieved from the online WiFi database, in the same way as the cell site database) to further discover the user's location. The order in which these take precedence is:

• GPS-based services
• WLAN-based / WiFi-based services
• Cell transmitter-based services

The software plots the streets in blue that are available with a yellow icon and a green circle around the estimated range of the cell site based on the transmitter's rated power (among other variables). The estimate is refined using the strength of the cell phone signal to estimate how close to the cell site the mobile device is.

As of December 15, 2008, this service is available for the following platforms:

• Android
• iOS (iPhone/iPod Touch/iPad)
• Windows Mobile
• Nokia/Symbian (S60 3rd edition only)
• Symbian OS (UIQ v3)
• BlackBerry
• Phones with Java-Platform (MIDP 2.0 and up), for example the Sony Ericsson K800i
• Palm OS (Centro and newer)
• Palm webOS (Palm Pre and Palm Pixi)

On November 4, 2009, Google Maps Navigation was released in conjunction with Google Android OS 2.0 Eclair on the Motorola Droid, adding voice commands, traffic reports, and street view support. The initial release is limited to the United States.

Google Maps Android 2.0.
Cell phones are being increasingly used for navigation assistance. However, written driving instructions are sometimes very confusing to follow. While navigation devices have become a billion dollar industry, Google Maps Navigation for Android 2.0 is free.

Features Provided in the Application:

• Search in plain English
• Search by voice
• Traffic view
• Search along route
• Satellite view
• Street View
• Car dock mode

Impact
Google Maps Navigation is free and this will have a major impact on the navigation industry. The drawback of Google Maps for Android is that an internet connection is required to get maps and related information from Google Maps, just like with iPhone’s Google Maps application. It may be possible for Google to circumvent the Internet requirement. A similar system is being developed for the iPhone.

Shares of Tom-Tom, Garmin and other navigation service providers fell by almost twenty-five percent after Google's announcement of Google Maps for Navigation. The application is only available initially to Verizon users with Android 2.0 or higher. It is doubtful that users will continue to pay for navigation service if Google provides it for free.

Google's Navigation was launched in the UK on 20 April 2010, although it is still unknown when this feature will come to the rest of the world.

Google Maps parameters

In Google Maps, URL parameters may be tweaked to offer views and options not normally available through on-screen controls.

For instance, the maximum zoom level offered is normally 18, but if higher-resolution images are available, changing the z parameter, which sets the zoom level, will allow the user to access them, as in this view of elephants or this view of people at a well deep in Chad, Africa using the parameter z=23.

Development history

Google Maps first started as a software application developed by Lars and Jens Rasmussen for the company Where2. In October 2004 the company was acquired by Google Inc where it transformed into the web application Google Maps. The application was first announced on the Google Blog on February 8, 2005, and was located at Google. It originally only supported users of Internet Explorer and Mozilla web browsers, but support for Opera and Safari was added on February 25, 2005, but currently Opera is removed from the system requirements list. As of September 2009 Internet Explorer 6.0+, Firefox 2.0+, Safari 3.1+, and Google Chrome are supported. It was in beta for six months before becoming part of Google Local on October 6, 2005.

In April 2005, Google created Google Ride Finder using Google Maps. In June 2005, Google released the Google Maps API. In July 2005, Google began Google Maps and Google Local services for Japan, including road maps. On July 22, 2005, Google released "Hybrid View". Together with this change, the satellite image data was converted from plate carrée to Mercator projection, which makes for a less distorted image in the temperate climes latitudes. In July 2005, in honor of the thirty-sixth anniversary of the Apollo Moon landing, Google Moon was launched. In September 2005, in the aftermath of Hurricane Katrina, Google Maps quickly updated its satellite imagery of New Orleans to allow users to view the extent of the flooding in various parts of that city. (Oddly, in March 2007, imagery showing hurricane damage was replaced with images from before the storm; this replacement was not made on Google Earth, which still uses post-Katrina imagery).

As of January 2, 2006, Google Maps featured road maps for the United States, Puerto Rico, Canada, the United Kingdom, Japan, and certain cities in the Republic of Ireland. Coverage of the area around Turin was added in time for the 2006 Winter Olympics. On January 23, 2006, Google Maps was updated to use the same satellite image database as Google Earth. On March 12, 2006, Google Mars was launched, which features a draggable map and satellite imagery of the planet Mars. In April 2006, Google Local was merged into the main Google Maps site. On April 3, 2006, version 2 of the Maps API was released. On June 11, 2006, Google added geocoding capabilities to the API, satisfying the most developer-requested feature for this service. On June 14, 2006, Google Maps for Enterprise was officially launched. As a commercial service, it features intranet and advertisement-free implementations. In July 2006 Google started including Google Maps business listings in the form of Local OneBoxes in the main Google search results. On December 9 Google integrates the PlusBox in the main search results. On December 19 Google added a feature that lets you add multiple destinations to your driving directions. Beginning in February 2007, buildings and subway stops are displayed in Google Maps "map view" for parts of New York City, Washington, D.C., London, San Francisco, and some other cities.

On January 29, 2007 Local Universal results were upgraded and more data included in the main Google results page. On February 28, 2007, Google Traffic info was officially launched to automatically include real-time traffic flow conditions to the maps of 30 major cities of the United States. On March 8, 2007, the Local Business Center was upgraded. On May 16, 2007 Google rolled out Universal search results, including more Map information on the main Google results page. On May 18, 2007 Google added neighborhood search capabilities. On May 29, 2007, Google driving directions support was added to the Google Maps API. On May 29, 2007, Street View was added, giving a ground-level 360-degree view of streets in some major cities in United States. On June 19, 2007, reviews were allowed to be added directly to businesses on Google Maps. On June 28, 2007, draggable driving directions] were introduced. On July 31, 2007, support for the hCard microformat was announced. Unfortunately, the implementation is broken. On August 21, 2007, Google announced a simple way to embed Google Maps into other websites. On September 13, 2007, 54 new countries were added to Google Maps in Latin America and Asia. On October 3, 2007, Google Transit was integrated into Google Maps making public transportation routing possible on Google Maps. On October 27, 2007, Google Maps started mapping the geoweb and showing the results in Google Maps. On October 27, 2007, Google Maps added a searchable interface for coupons in the business listings. On November 27, 2007, "Terrain" view showing basic topographic features was added. The button for "Hybrid" view was removed, and replaced with a "Show labels" checkbox under the "Satellite" button to switch between "Hybrid" and "Satellite" views.

On January 22, 2008, Google expanded the Local Onebox from 3 business listings to 10. On February 20, 2008, Google Maps allowed searches to be refined by User Rating & neighborhoods. On March 18, 2008, Google allowed end users to edit business listings and add new places. On March 19, 2008, Google added unlimited category options in the Local Business Center. On April 2, 2008, Google added contour lines to the Terrain view. In April 2008, a button to view recent Saved Locations was added to the right of the search field. In May 2008, a "More" button was added alongside the "Map", "Satellite", and "Terrain" buttons, permitting access to geographically-related photos on Panoramio and articles on Wikipedia. On May 15, 2008, Google Maps was ported to Flash and ActionScript 3 as a foundation for richer internet applications. On July 15, 2008, walking directions were added. On August 4, 2008, Street View launched in Japan and Australia. On August 15, 2008, the user interface was redesigned. On August 29, 2008, Google signed a deal under which GeoEye would supply them with imagery from a satellite, and introduced the Map Maker tool for creation of map data. On September 9, 2008, a reverse business lookup feature was added. On September 23, 2008, information for the New York City Metropolitan Transit Authority was added. On October 7, 2008, GeoEye-1 took its first image, a bird's-eye view of Kutztown University in Pennsylvania. On October 26, 2008, reverse geocoding was added to the Maps API. On November 11, 2008, Street View in Spain, Italy, and France was introduced. On November 23, 2008, AIR support for the Maps API for Flash was added. On November 25, 2008, a new user interface for Street View was introduced. On November 27, 2008, maps, local business information, and local trends for China were introduced. On December 9, 2008, 2x Street View coverage was introduced.

In May, 2009, a new Google Maps logo was introduced. In early October 2009, Google replaced Tele Atlas as their primary supplier of geospatial data in the U.S. version of Maps and use their own data. In October 2009, the railroads were redone, featuring a slightly new look and updated, removing older lines. Also in the same month, maps in several areas were changed to include paper streets and other odd roads that don't exist, as well as lot lines showing up on the map interface. On February 11, 2010, Google Maps Labs was added. On March 11, 2010, Street View in the United Kingdom, Hong Kong, Macau, and more locations in Japan were launched. On May 25, 2010, public transportation routing for Denmark was added by integrating with Rejseplanen.dk.

Google's use of Google Maps

The main Google Maps site includes a local search feature, which can be used to locate businesses of a certain type in a geographic area.

Google Ditu

Google Ditu (谷歌地图 lit. "Google Maps") was released to the public on February 9, 2007, and replaced the old Google Bendi (谷歌本地 lit. "Google Local"). This is the Chinese localized version of Google Maps and Google Local services.

In order to be compliant with the requirements of Chinese law, Google had to remove or modify some Google Maps features in Google Ditu:

• Google Ditu does not allow overlay of user-generated content from Panoramio, Youtube, Wikipedia and webcams.
• Google Ditu shows the disputed border areas between China and India as being part of China, while on Google Maps those disputed areas are shown inside dotted lines.

Google Moon

Main article: Google Moon

File:Google-moon.png

Google Moon

In honor of the 36th anniversary of the Apollo 11 moon landing on July 20, 1969, Google took public domain imagery of the Moon, integrated it into the Google Maps interface, and created a tool called Google Moon. By default this tool, with a reduced set of features, also displays the points of landing of all Apollo spacecraft to land on the Moon. It also included an easter egg, displaying a Swiss cheese design at the highest zoom level, which Google has since removed. A recent collaborative project between NASA Ames Research Center and Google is integrating and improving the data that is used for Google Moon. This is the Planetary Content Project. Google Moon was linked from a special commemorative version of the Google logo displayed at the top of the main Google search page for July 20, 2005 (UTC) .

Google Mars

Main article: Google Mars

File:GoogleMars.png

Google Mars

Google Mars provides a visible imagery view, like Google Moon, as well as infrared imagery and shaded relief (elevation) of the planet Mars. Users can toggle between the elevation, visible, and infrared data, in the same manner as switching between map, satellite, and hybrid modes of Google Maps. In collaboration with NASA scientists at the Mars Space Flight Facility located at Arizona State University, Google has provided the public with data collected from two NASA Mars missions, Mars Global Surveyor and 2001 Mars Odyssey.

Now, with Google Earth 5 it is possible to access new improved Google Mars data at a much higher resolution, as well as being able to view the terrain in 3D, and viewing panoramas from various Mars landers in a similar way to Google Street View.

Google Sky

Main article: Google Sky

On August 27, 2007, Google introduced Google Sky, an online space mapping tool that allows users to pan through a map of the visible universe, using photographs taken by the Hubble Space Telescope.

Google Ride Finder

Google launched an experimental Google Maps-based tool called Ride Finder, tapping into in-car GPS units for a selection of participating taxi and limousine services. The tool displays the current location of all supported vehicles of the participating services in major U.S. cities, including Chicago and San Francisco, on a Google Maps street map. As of 2009 the tool seems to be discontinued. Not to be confused with carpooling.

Google Transit

In December 2005, Google launched Google Transit on Google Labs, a 20% project of Chris Harrelson and Avichal Garg. Google Transit launched initially with support for Portland, Oregon, and now includes hundreds of cities in the United States, Canada, Europe, Asia, Africa, Australia, and New Zealand. The service calculates route, transit time and cost, and can compare the trip to one using a car. In October 2007 Google Transit graduated from Google Labs and became fully integrated into Google Maps.

Coverage

The coverage of Google Transit is publicly available. It is spread worldwide, in hundreds of cities and sometimes in entire countries such as China, Japan, Switzerland. The coverage of major cities in the United States and in Canada is almost exhaustive, with a few notable exceptions (as of August 2010) such as Washington, DC and Toronto, ON.

In some areas, such as the United Kingdom, Google Transit covers only part of the transit agencies. For example Transport for London does not provide its data to Google Transit, but some bus companies do, leading to a warning "The coverage may be incomplete" when looking for transit directions in or around London.

In other areas, Google Transit does not provide public transit directions, but still provides the Transit Layer which overlays the schematic of the transit lines on the map. Notable examples include Paris, Berlin, Mexico City and many other capitals around the world.

Google Biking directions

On March 10, 2010, Google added the possibility to search for biking directions on Google Maps. Optimal routes are calculated from traffic, elevation change, bike paths, bike lanes, and preferred roads for biking. An optional layer also shows different types of biking paths, from bike-only trails to preferred roads. This service is only available in the US for now.

Google My Maps

In April 2007, My Maps was a new feature added to Google's local search maps. My Maps lets users and businesses create their own map by positioning markers, polylines and polygons onto a map. The interface is a straightforward overlay on the map. A set of eighty-four pre-designed markers is available, ranging from bars and restaurants to webcam and earthquake symbols. Polyline and Polygon color, width and opacity are selectable. Maps modified using My Maps can be saved for later viewing and made public or marked as unlisted, in which case a user will need the saved URL with a 42 character unique ID.

Each element added to a My Map has an editable tag. This tag can contain text, rich text or HTML. Embeddable video and other content can be included within the HTML tag.

Upon the launch of My Maps there was no facility to embed the created maps into a webpage or blog. A few independent websites have now produced tools to let users embed maps and add further functionality to their maps. This has been resolved with version 2.78.

Google Street View

Main article: Google Street View

On May 25, 2007, Google released Street View, a new feature of Google Maps which provides 360° panoramic street-level views of various U.S. cities. On this date, the feature only included five cities, but has since expanded to thousands of locations in Australia, Canada, China, the Czech Republic, France, Hong Kong, Italy, Japan, Mexico, New Zealand, South Africa, Spain, Sweden, Switzerland, the Netherlands, Norway, the United Kingdom, and the United States.

In August 2008, Australia was added to the Street View feature with nearly all Australian highways, roads and streets having the feature. In addition in that month Japan was added and the Tour de France route was added on July 2 of that year. In December 2008, New Zealand was added to street view. United Kingdom, Australia and New Zealand are the only countries to date with almost all roads and highways featured.

July 2009, Google begins mapping college campuses and surrounding paths and trails. Mexico's main cities and tourist points are added to Street View.

Street View garnered much controversy after its release because of privacy concerns about the uncensored nature of the panoramic photographs. Since then, Google has begun blurring faces through automatic face detection.

Google Aerial View

In May 2010, Google released Aerial View, a new feature of Google Maps. It was introduced first for major South African cities, including Durban, Bloemfontein, Port Elizabeth and Johannesburg.

Google Latitude

Main article: Google Latitude

Google Latitude is a feature from Google that lets users share their physical locations with other people. This service is based on Google Maps, specifically on mobile devices. There's an iGoogle widget for Desktops and Laptops as well. Some concerns have been expressed about the privacy issues raised by the use of the service.

Google Flu Shot Finder

Google Flu Shot Finder allows users in the United States to identify locations where both the pandemic H1N1/09 virus and seasonal flu vaccines are available near a given address or ZIP code.

Monopoly City Streets

Monopoly City Streets is a live worldwide version of the game Monopoly using Google Maps as the game board. It was created by Google and Hasbro. The game has now ended.

Mashups

Main article: Mashup (web application hybrid)

Google maps links to the geo-tags placed in Wikipedia articles. It also links to photos with GPS tags from Panoramio.

Copyright

The Google Maps terms and conditions state that usage of material from Google Maps is regulated by Google Terms of Service and some additional restrictions.

Criticism

See also: Satellite map images with missing or unclear data

Street map overlays, in some areas, may not match up precisely with the corresponding satellite images. The street data may be entirely erroneous, or simply out of date:

" 'The biggest challenge is the currency of data, the authenticity of data,' said Google Earth representative Brian McLendon. In other words: The main complaints the Google guys get are 'that's not my house' and 'that's not my car.' Google Maps satellite images are not in real time; they are several years old."

As a result, in March 2008 Google added a feature to edit the locations of houses and businesses.

Restrictions have been placed on Google Maps through the apparent censoring of locations deemed potential security threats. In some cases the area of redaction is for specific buildings, but in other cases, such as Washington, D.C., the restriction is to use outdated imagery. These locations are fully listed on Satellite map images with missing or unclear data.

Google Maps has difficulty processing road data when dealing with cross-boundary situations. For example, users are unable to obtain a route from Hong Kong to Shenzhen via Shatoujiao, because Google Maps does not display and plan the road map of two overlapping places.

Sometimes objects and even regions on Google Maps are hidden by clouds. For example, the mast of Arbrå Transmitter near Bollnäs in Sweden is, as of August 25, 2010, hidden under a cloud.

Sometimes the names of geographical locations are inaccurate. An example of this type of error may be found in Google Maps Laona, Wisconsin. In this instance Google Maps identifies one of the town's two major lakes as "Dawson Lake"; the USGS, State of Wisconsin, and local government maps all identify that map feature as "Scattered Rice Lake". Another example is Samoa, labeled with "Western Samoa", accurate only as recently as 1997.

The Wikipedia option of Google maps has introduced interesting errors by incorporating incorrect or wildly misleading data:

• Chennai district of India found in the Arctic's Kara Sea
• Giraavaru (Kaafu Atoll) in the Arctic instead of Male' Atoll in the Indian Ocean
• South Magnetic Pole located very near the North Magnetic Pole

Google collates business listings from multiple on-line and off-line sources. To reduce duplication in the index, Google's algorithm combines listings automatically based on address, phone number, or geocode, but sometimes information for separate businesses will be inadvertently merged with each other, resulting in listings inaccurately incorporating elements from multiple businesses.

Google has also recruited volunteers to check and correct ground truth data.

There are some differences in frontier alignments between Google Ditu and Google Maps. On Google Maps, sections of the Chinese border with India and Pakistan are shown with dotted lines, indicating areas or frontiers in dispute. However, Google Ditu shows the Chinese frontier strictly according to Chinese claims with no dotted lines indicating the border with India and Pakistan. For example, the area now administered by India called Arunachal Pradesh (referred to as "South Tibet" by China) is shown inside the Chinese frontier by Google Ditu, with Indian highways ending abruptly at the Chinese claim line. Google Ditu also shows Taiwan and the South China Sea Islands as part of China. As of May 2009, Google Ditu's street map coverage of Taiwan also omits major state organs, such as the Presidential Palace, the five Yuans, and the Supreme Court.

There are some differences between ditu.google.cn and ditu.google.com. For example, the former does not feature My Maps. On the other hand, while the former displays virtually all text in Chinese, the latter displays most text (user-selectable real text as well as those on map) in English. This behavior of displaying English text is not consistent but intermittent - sometimes it is in English, sometimes it is in Chinese. The criteria for choosing which language is displayed is not known.

Phantom Settlements

Google Maps have featured the following villages on their maps which in fact do not exist:

• Argleton - was situated near Aughton, Lancashire
• Dummy1325 - situated near Holmeswood, Lancashire
• Mawdesky - situated near the village of Mawdesley, Lancashire
• Penworthamdale - situated near the town of Penwortham, Lancashire.

Map projection

Google Maps is based on a close variant of the Mercator projection. If the earth were perfectly spherical, the projection would be the same as the Mercator. Google Maps uses the formulæ for the spherical Mercator, but the coordinates of features on Google Maps are the GPS coordinates based on the WGS 84 datum. The difference between a sphere and the WGS 84 ellipsoid causes the resultant projection not to be precisely conformal. The discrepancy is meaningless at the global scale but causes maps of local areas to deviate slightly from true ellipsoidal Mercator maps at the same scale.

Because the Mercator projects the poles at infinity, Google Maps cannot show the poles. Instead it cuts off coverage at 85° north and south. This is not considered a limitation, given the purpose of the service. There are no roads at those latitudes.

Comparable services

• Bing Maps – Microsoft's mapping service with road maps and aerial/satellite imagery
  • TerraServer-USA – public domain (older than five years) satellite imagery via Microsoft servers
  • Bing Maps for Enterprise - formerly Microsoft Virtual Earth
• deCarta - Drill Down Server - web services platform offers AJAX, Flash, iPhone APIs for mapping, geocoding, routing and reverse geocoding services.
• Géoportail – a French rival offering detailed aerial photographs of French territories
• MapQuest
• Mappy.com - a French rival
• Multimap.com
• OpenStreetMap – a royalty free, editable map of the world
• Ovi Maps – a service offered by Nokia that allows synchronizing with user's mobile phones
• Pictometry – a birdseye imagery provider which can be integrated into all mapping programs
• Seat Pagine Gialle – an Italian competitor offering detailed satellite pictures of Italian territories and navigable street level panoramas of Rome (similar to Street View)
• Terralink International
• ViaMichelin
• Yahoo! Maps
• ABmaps

See also

• Bhuvan
• Comparison of web map services
• lmx filetype
• Placeopedia
• PlaceSpotting
• Ship location mapping service
• WikiMapia, a mashup combining Google Maps and a wiki aimed at "describing the whole planet earth"
• Wikipediavision

External links

• Google Maps
  • Mobile phone version
  • Google Sky
  • Google Moon
  • Google Mars
  • Google Transit
  • Google Flushot
• Google Maps Development
• Google Maps parameters
• Desktop client for Mars provided by NASA.
• Mars maps provided by the Mars Space Flight Facility Arizona State University