Google Maps
Google Maps (for a time named Google Local) is a free web map server application and technology provided by Google that powers many map-based services including Google Maps, Google Ride Finder and embedded maps on third-party websites via the Google Maps API. It offers street maps, a route planner and an urban business locator for Australia, Canada, Japan, New Zealand, the United States, most western European countries, numerous cities in Eastern Europe (street coverage in Moscow and St. Petersburg and main highways connecting Kiev, Minsk, Vilnius, Riga, Tallinn, and others), the Canary Islands, and Brazil, and satellite images for the whole world.
A related product is Google Earth, a standalone Apple Mac, Windows and Linux program that offers enhanced globe-viewing features.
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Features
Google Maps features a map that can be navigated by dragging the mouse, or zoomed in (scrolling the mouse wheel up) and out (scrolling the mouse wheel down) to show detailed street information. The user can also control the map with the arrow keys to move to the desired location. To allow for quick movement, the "+" and "-" keys can be used to control the zoom level. Users may enter an address, intersection or general area to quickly find it on the map.
Search results can be restricted to a certain area, thanks to Google Local. For example, someone can enter a query such as "Waffles in Ottawa"[1] to find restaurants serving waffles near the city. This can be used to find a wide variety of businesses, such as theatres, restaurants or hotels.
Like many other map services, Google Maps allows for the creation of driving directions. It gives the user a step-by-step list of how to get to their destination, along with an estimate of the time required to reach it and the distance between the two locations.
Google Maps offers three viewing modes by default: Map (Street map views), Satellite (satellite and high-resolution aerial photographs) and Hybrid (Street maps overlaid on satellite and high-resolution aerial photographs).
The "link to this page" link on each Google Maps map targets a URL which can be used to find the location on the map at a later time. The latitude and longitude can be used as input to NASA World Wind or TerraServer-USA, which in some cases have higher-resolution imagery.
Satellite view
Google Maps provides high-resolution (full-zoom) satellite images for most urban areas in Canada and the United States (including Hawaii, Alaska, Puerto Rico, and the U.S. Virgin Islands) as well as parts of Australia, France, Iceland, Italy, Iraq, Japan, the Bahamas, Bermuda, Kuwait, Mexico, the Netherlands, the United Kingdom and many other countries. Google Maps also covers the cities of Moscow, Istanbul, and also Bangalore, Chennai, Salem, Mumbai and New Delhi in India.
All the images shown in Google Maps' satellite mode are at least a year old and in some places up to five years old. Despite this various governments have complained over the potential for terrorists to use the satellite images in planning attacks on nuclear power stations. 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 until recently, the United States Capitol and the White House (which formerly featured erased housetop). Other well-known government installations are visible including the infamous Area 51 in the Nevada desert.
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 such as Google Sightseeing and Google Globetrotting 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 stadiums and unique earth formations.
Implementation
Like other Google web applications, a large amount of JavaScript was used to create Google Maps. As the user drags the map, the grid squares are downloaded from the server and displayed to the user. When a user searches for a business, the location is pin-pointed with a red pin, which is actually a transparent PNG placed over the map. The technique of providing greater user-interactivity by performing asynchronous network requests with Javascript and XML has recently become known as Ajax. Specifically, Google Maps was built using the AjaXSLT framework.
The GIS (map) data used in Google Maps are provided by Tele Atlas and NAVTEQ, while the small patches of high-resolution satellite imagery are largely provided by DigitalGlobe and its QuickBird satellite, with some imagery also from government sources. The main global imagery base called NaturalVue was derived from Landsat 7 imagery by MDA Federal (formerly Earth Satellite Corporation). This global image base provides the essential foundation for the entire application.
The underlying technology used in both Google and Yahoo! maps is available from deCarta (formerly Telcontar)[2].
Extensibility and customization
As the Google Maps code is almost entirely JavaScript and XML, some end-users 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. Some of the more well-known of these "Google Maps Hacks" include tools that display locations of Craigslist rental properties [4], student apartment rentals [5], and local map Chicago crime data [6] (or check Misdaadkaart.nl showing crimes of one entire country[7]). The script-insertion tool Greasemonkey provides a large number of client-side scripts to customize Google Maps data, and the mygmaps.com website provides an interface for easily adding your own set of locations and viewing them on Google Maps.
Combined with photo sharing websites such as Flickr, a phenomenon called "memory maps" emerged. Using copies of the Keyhole satellite photos of their home towns or other favorite places, the users take advantage of image annotation features to provide personal histories and information regarding particular points of the area.
Google Maps API
The Google Maps API was created by Google to facilitate developers integrating Google Maps into their web sites, with their own data points. It is a free service, that currently does not contain ads, but Google states in their terms of use [8] that they reserve the right to display ads in the future.
By using the Google Maps API you can embed the full Google Maps on an external web site (minus driving directions and KML). Start by creating an API Key [9], it will be bound to the web site and directory you enter when creating the key. Creating your own map interface involves adding the Google JavaScript code to your page, and then using Javascript functions to add points to the map.
When the API first launched it lacked the ability to geocode addresses, requiring you to manually add points in (latitude, longitude) format. This has since been rectified.
At the same time as the release of the Google Maps API, Yahoo! released their own Maps API [10] . Both were released to coincide with the O'Reilly Web 2.0 Conference. Yahoo! Maps lacks international support and aerial photos, but included a geocoder in the first release.
Development
Google Maps was first announced on the Google Blog on February 8, 2005 and was located at http://maps.google.com/. It originally only supported users of Internet Explorer and Mozilla web browsers, but support for Opera and Safari was added on February 25, 2005. Currently (July 1, 2006) Internet Explorer 6.0+, Firefox 0.8+, Safari 1.2.4+, Netscape 7.1+, Mozilla 1.4+, and Opera 8.02+ are supported (see Google Maps Help). It was in beta for 6 months before becoming part of Google Local on October 6, 2005.
Google's use of Google Maps
The main Google Maps site includes a local search feature, finding businesses of a certain category in a geographic area.
Copyright
Google Maps Terms and Conditions[4] state that usage of material from Google Maps is regulated by Google Terms of Service[5] and some additional restrictions. Terms and Conditions, among others, state:
- For individual users, Google Maps [...] is made available for your personal, non-commercial use only. For business users, Google Maps is made available for your internal use only and may not be commercially redistributed [...][6]
Criticism
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 authenticy 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. [7]
Google maps has gained most acclaim by web developers. GIS professionals however, tend to regard Google maps as a rather simplistic viewing tool compared to the features offered by standalone GIS applications.
There is also some disappointment among developers that the potential of Google's geocoding technology is limited by legal restrictions in some countries for web application development, notably the UK, where postcodes cannot be easily translated into latitudes and longitudes like Zip codes in the US. This is due to the crown copyright over this geographical data. Some sites have managed to circumvent this problem by purchasing their own postcode data and combining this with Google Maps. The usage of Google Maps on a large scale outside the US remains limited.
See also
References
- ↑ http://maps.google.com/maps?q=Georgetown,+Malaysia&spn=0.312132,0.515654&t=k&hl=en
- ↑ http://www.decarta.com/
- ↑ http://abcnews.go.com/Technology/wireStory?id=832264
- ↑ http://www.housingmaps.com/
- ↑ http://www.gooffcampus.com/
- ↑ http://www.chicagocrime.org/
- ↑ http://www.misdaadkaart.nl/
- ↑ "Google Maps API - Terms of use". http://www.google.com/apis/maps/terms.html.
- ↑ "Google Maps API key". http://www.google.com/apis/maps/signup.html.
- ↑ "Yahoo! Maps API". http://developer.yahoo.com/maps/index.html.
- ↑ http://mars.google.com/
- ↑ http://www.google.com/mars/about.html
31% from 2007)
References
- Adapted from the Wikipedia article, "Google_Maps" http://en.wikipedia.org/wiki/Google_Maps, used under the GNU Free Documentation License
