Web mapping

Web mapping is the process of designing, implementing, generating and delivering maps on the World Wide Web and its product. While web mapping primarily deals with technological issues, web cartography additionally studies theoretic aspects: the use of web maps, the evaluation and optimization of techniques and workflows, the usability of web maps, social aspects, and more. Web GIS is similar to web mapping but with an emphasis on analysis, processing of project specific geodata and exploratory aspects. Often the terms web GIS and web mapping are used synonymously, even if they don't mean exactly the same. In fact, the border between web maps and web GIS is blurry. Web maps are often a presentation media in web GIS and web maps are increasingly gaining analytical capabilities.

A special case of web maps are mobile maps, displayed on mobile computing devices, such as mobile phones, smart phones, PDAs and GPS. If the maps on these devices are displayed by a mobile web browser or web user agent, they can be regarded as mobile web maps. If the mobile web maps also display context and location sensitive information, such as points of interest, the term Location-based services is frequently used."

"The use of the web as a dissemination medium for maps can be regarded as a major advancement in cartography and opens many new opportunities, such as realtime maps, cheaper dissemination, more frequent and cheaper updates of data and software, personalized map content, distributed data sources and sharing of geographic information. It also implicates many challenges due to technical restrictions (low display resolution and limited bandwidth, in particular with mobile computing devices, many of which are physically small, and use slow wireless Internet connections), copyright and security issues, reliability issues and technical complexity. While the first web maps were primarily static, today's web maps can be fully interactive and integrate multiple media. This means that both web mapping and web cartography also have to deal with interactivity, usability and multimedia issues."

Development and implementation

The advent of web mapping can be regarded as a major new trend in cartography. Previously, cartography was restricted to a few companies, institutes and mapping agencies, requiring expensive and complex hardware and software as well as skilled cartographers and geomatics engineers. With the rise of web mapping, a range of data and technology was born - from free data generated by OpenStreetMap to proprietary datasets owned by Navteq, Google, Waze, and others. A range of free software to generate maps has also been generated, alongside proprietary tools like ArcGIS. As a result, the barrier to entry for creating maps on the web has shifted from that of the paper atlas and other traditional cartography.

Types of web maps

A first classification of web maps has been made by Kraak. He distinguished static and dynamic web maps and further distinguished interactive and view only web maps. However, today in the light of an increased number of different web map types, this classification needs some revision. Today, there are additional possibilities regarding distributed data sources, collaborative maps, personalized maps, etc.

Analytic web maps

These web maps offer GIS analysis, either with geodata provided, or with geodata uploaded by the map user. As already mentioned, the borderline between analytic web maps and web GIS is blurry. Often, parts of the analysis are carried out by a serverside GIS and the client displays the result of the analysis. As web clients gain more and more capabilities, this task sharing may gradually shift.

Animated web maps

Animated Maps show changes in the map over time by animating one of the graphical or temporal variables. Various data and multimedia formats and technologies allow the display of animated web maps: SVG, Adobe Flash, Java, QuickTime, etc., also with varying degrees of interaction. Examples for animated web maps are weather maps, maps displaying dynamic natural or other phenomena (such as water currents, wind patterns, traffic flow, trade flow, communication patterns,social studies projects, and for college life, etc.).

Collaborative web maps

Main article: Collaborative mapping

Collaborative maps are still new, immature and complex to implement, but show a lot of potential. The method parallels the Wikipedia project where various people collaborate to create and improve maps on the web. Technically, an application allowing simultaneous editing across the web would have to ensure that geometric features being edited by one person are locked, so they can't be edited by other persons at the same time. Also, a minimal quality check would have to be made, before data goes public. Some collaborative map projects:

• HERE Map Creator
• Google Map Maker
• OpenStreetMap
• WikiMapia
• meta:Maps - survey of Wikimedia map proposals on Wikipedia:Meta
• (Please add additional notes, references and examples here!)

Dynamically created web maps

These maps are created on demand each time the user reloads the webpages, often from dynamic data sources, such as databases. The webserver generates the map using a web map server or self written software.

Online atlases

Atlas projects often went through a renaissance when they made a transition to a web based project. In the past, atlas projects often suffered from expensive map production, small circulation and limited audience. Updates were expensive to produce and took a long time until they hit the public. Many atlas projects, after moving to the web, can now reach a wider audience, produce cheaper, provide a larger number of maps and map types and integrate with and benefit from other web resources. Some atlases even ceased their printed editions after going online, sometimes offering printing on demand features from the online edition. Some atlases (primarily from North America) also offer raw data downloads of the underlying geospatial data sources.

Realtime web maps

Realtime maps show the situation of a phenomenon in close to realtime (only a few seconds or minutes delay). Data is collected by sensors and the maps are generated or updated at regular intervals or immediately on demand. Examples are weather maps, traffic maps or vehicle monitoring systems.

Static web maps

A USGS DRG - a static map

Static web pages are view only with no animation and interactivity. They are only created once, often manually and infrequently updated. Typical graphics formats for static web maps are PNG, JPEG, GIF, or TIFF (e.g., drg) for raster files, SVG, PDF or SWF for vector files. Often, these maps are scanned paper maps and had not been designed as screen maps. Paper maps have a much higher resolution and information density than typical computer displays of the same physical size, and might be unreadable when displayed on screens at the wrong resolution.

Advantages of web maps

A surface weather analysis for the United States on October 21, 2006.

• Web maps can easily deliver up to date information. If maps are generated automatically from databases, they can display information in almost realtime. They don't need to be printed, mastered and distributed. Examples:
  • A map displaying election results, as soon as the election results become available.
  • A map displaying the traffic situation near realtime by using traffic data collected by sensor networks.
  • A map showing the current locations of mass transit vehicles such as buses or trains, allowing patrons to minimize their waiting time at stops or stations, or be aware of delays in service.
  • Weather maps, such as NEXRAD.
• Software and hardware infrastructure for web maps is cheap. Web server hardware is cheaply available and many open source tools exist for producing web maps.
• Product updates can easily be distributed. Because web maps distribute both logic and data with each request or loading, product updates can happen every time the web user reloads the application. In traditional cartography, when dealing with printed maps or interactive maps distributed on offline media (CD, DVD, etc.), a map update caused serious efforts, triggering a reprint or remastering as well as a redistribution of the media. With web maps, data and product updates are easier, cheaper, and faster, and can occur more often.
• They work across browsers and operating systems. If web maps are implemented based on open standards, the underlying operating system and browser do not matter.
• Web maps can combine distributed data sources. Using open standards and documented APIs one can integrate (mash up) different data sources, if the projection system, map scale and data quality match. The use of centralized data sources removes the burden for individual organizations to maintain copies of the same data sets. The downside is that one has to rely on and trust the external data sources.
• Web maps allow for personalization. By using user profiles, personal filters and personal styling and symbolization, users can configure and design their own maps, if the web mapping systems supports personalization. Accessibility issues can be treated in the same way. If users can store their favourite colors and patterns they can avoid color combinations they can't easily distinguish (e.g. due to color blindness).
• Web maps enable collaborative mapping. Similar to the Wikipedia project, web mapping technologies, such as DHTML/Ajax, SVG, Java, Adobe Flash, etc. enable distributed data acquisition and collaborative efforts. Examples for such projects are the OpenStreetMap project or the Google Earth community. As with other open projects, quality assurance is very important, however!
• Web maps support hyperlinking to other information on the web. Just like any other web page or a wiki, web maps can act like an index to other information on the web. Any sensitive area in a map, a label text, etc. can provide hyperlinks to additional information. As an example a map showing public transport options can directly link to the corresponding section in the online train time table.
• It is easy to integrate multimedia in and with web maps. Current web browsers support the playback of video, audio and animation (SVG, SWF, QuickTime, and other multimedia frameworks).

Disadvantages of web maps and problematic issues

• Reliability issues – the reliability of the internet and web server infrastructure is not yet good enough. Especially if a web map relies on external, distributed data sources, the original author often cannot guarantee the availability of the information.
• Geodata are expensive – Unlike in the US, where geodata collected by governmental institutions is usually available for free or cheap, geodata is usually very expensive in Europe or other parts of the world.
• Bandwidth issues – Web maps usually need a relatively high bandwidth.
• Limited screen space – As with other screen based maps, web maps have the problem of limited screen space. This is in particular a problem for mobile web maps and location based services where maps have to be displayed in very small screens with resolutions as low as 100×100 pixels. Hopefully, technological advances will help to overcome these limitations.
• Quality and accuracy issues – Many web maps are of poor quality, both in symbolization, content and data accuracy.
• Complex to develop – Despite the increasing availability of free and commercial tools to create web mapping and web GIS applications, it is still a complex task to create interactive web maps. Many technologies, modules, services and data sources have to be mastered and integrated.
• Immature development tools – Compared to the development of standalone applications with integrated development tools, the development and debugging environments of a conglomerate of different web technologies is still awkward and uncomfortable.
• Copyright issues – Many people are still reluctant to publish geodata, especially in light of the fact that geodata are expensive in some parts of the world. They fear copyright infringements of other people using their data without proper requests for permission.
• Privacy issues – With detailed information available and the combination of distributed data sources, it is possible to find out and combine a lot of private and personal information of individual persons. Properties and estates of individuals are now accessible through high resolution aerial and satellite images throughout the world to anyone.

History of web mapping

Event types

Cartography-related events Technical events directly related to web mapping General technical events Events relating to Web standards

This section contains some of the milestones of web mapping, online mapping services and atlases.

• 1989-90: Birth of the WWW, WWW invented at CERN for the exchange of research documents.
• 1993-07: Xerox PARC Map Viewer, The first mapserver based on CGI/Perl, allowed reprojection styling and definition of map extent.
• 1994: The World Wide Earthquake Locator, the first interactive web mapping mashup was released, based on the Xerox PARC map view.
• 1994-06: The National Atlas of Canada, The first version of the National Atlas of Canada was released. Can be regarded as the first online atlas.
• 1995: The Gazetteer for Scotland, The prototype version of the Gazetteer for Scotland was released. The first geographical database with interactive mapping.
• 1995: MapGuide, First introduced as Argus MapGuide.
• 1996-02: Mapquest, The first popular online Address Matching and Routing Service with mapping output.
• 1996-06: MultiMap, The UK-based MultiMap website launched offering online mapping, routing and location based services. Grew into one of the most popular UK web sites.
• 1996-11: Geomedia WebMap 1.0, First version of Geomedia WebMap, already supports vector graphics through the use of ActiveCGM.
• 1996-fall: MapGuide, Autodesk acquired Argus Technologies.and introduced Autodesk MapGuide 2.0.

National Atlas of the United States logo

• 1997-06: US Online National Atlas Initiative, The USGS received the mandate to coordinate and create the online National Atlas of the United States of America [3].
• 1997-07: UMN MapServer 1.0, Developed as Part of the NASA ForNet Project. Grew out of the need to deliver remote sensing data across the web for foresters.
• 1997-10: GeoInfoMapper - GeoInfo Solutions developed the first Java GIS Applet called 'JavaMap'. The application supported the export and conversion of MapInfo data for display in the thematic mapping tool for the web. GeoinfoMapper was demonstrated at the Victoria Computer Show in 1997 and referenced in the Universal Locator project at UC Berkeley School of Information.
• 1998-06: Terraserver USA, A Web Map Service serving aerial images (mainly b+w) and USGS DRGs was released. One of the first popular WMS. This service is a joint effort of USGS, Microsoft and HP.
• 1998-07: UMN MapServer 2.0, Added reprojection support (PROJ.4).
• 1998-08: MapObjects Internet Map Server, ESRI's entry into the web mapping business.
• 1999-08: National Atlas of Canada, 6th edition, This new version was launched at the ICA 1999 conference in Ottawa. Introduced many new features and topics. Is being improved gradually, since then, and kept up-to-date with technical advancements.
• 2000-02: ArcIMS 3.0, The first public release of ESRI's ArcIMS.
• 2000-06: ESRI Geography Network, ESRI founded Geography Network to distribute data and web map services.
• 2000-06: UMN MapServer 3.0, Developed as part of the NASA TerraSIP Project. This is also the first public, open source release of UMN Mapserver. Added raster support and support for TrueType fonts (FreeType).
• 2001 GeoServer, starts of the GeoServer project (Geoserver History)
• 2001-06: MapScript [4] 1.0 for UMN MapServer, Adds a lot of flexibility to UMN MapServer solutions.
• 2001-09: Tirolatlas, A highly interactive online atlas, the first to be based on the SVG standard.
• 2002-06: UMN MapServer 3.5, Added support for PostGIS and ArcSDE. Version 3.6 adds initial OGC WMS support.
• 2002-07: ArcIMS 4.0, Version 4 of the ArcIMS web map server.

Screenshot from NASA World Wind

• 2003-06: NASA World Wind, NASA World Wind Released. An open virtual globe that loads data from distributed resources across the internet. Terrain and buildings can be viewed 3 dimensionally. The (XML based) markup language allows users to integrate their own personal content. This virtual globe needs special software and doesn't run in a web browser.
• 2003-07: UMN MapServer 4.0, Adds 24bit raster output support and support for PDF and SWF.
• 2004-07: OpenStreetMap, an open source, open content world map founded by Steve Coast.
• 2005-02: Google Maps, The first version of Google Maps. Based on raster tiles organized in a quad tree scheme, data loading done with XMLHttpRequests. This mapping application became highly popular on the web, also because it allowed other people to integrate google map services into their own website.
• 2005-04: UMN MapServer 4.6, Adds support for SVG.

• 2005-06: Google Earth, The first version of Google Earth was released building on the virtual globe metaphor. Terrain and buildings can be viewed 3 dimensionally. The KML (XML based) markup language allows users to integrate their own personal content. This virtual globe needs special software and doesn't run in a web browser.
• 2005-06 OpenLayers, the first version of the OpenSource Javascript library OpenLayers.
• 2006-05: WikiMapia Launched
• 2009-01 Nokia makes Ovi Maps free on its smartphones.

Web mapping technologies

The potential number of technologies to implement web mapping projects is almost infinite. Any programming environment, programming language and serverside framework can be used to implement web mapping projects. In any case, both server and client side technologies have to be used. Following is a list of potential and popular server and client side technologies utilized for web mapping.

• Spatial databases are usually object relational databases enhanced with geographic data types, methods and properties. They are necessary whenever a web mapping application has to deal with dynamic data (that changes frequently) or with huge amount of geographic data. Spatial databases allow spatial queries, sub selects, reprojections, geometry manipulations and offer various import and export formats. A popular example for an open source spatial database is PostGIS. MySQL also implements some spatial features, although not as mature as PostGIS. Commercial alternatives are Oracle Spatial or spatial extensions of Microsoft SQL Server and IBM DB2. The OGC Simple Features for SQL Specification is a standard geometry data model and operator set for spatial databases. Most spatial databases implement this OGC standard.
• WMS servers can generate maps on request, using parameters, such as map layer order, styling/symbolization, map extent, data format, projection, etc. The OGC Consortium defined the WMS standard to define the map requests and return data formats, while other systems use standards like Tile Map Service for a similar purpose. Typical image formats for the map result are PNG, JPEG, GIF or SVG. There are open source WMS Servers such as UMN Mapserver and Mapnik. Commercial alternatives exist from most commercial GIS vendors, such as ESRI ArcIMS and CadCorp.

See also

• Comparison of web map services
• Geographic Information Systems (GIS)
• List of online map services
• Neogeography
• Public Participation GIS (PPGIS)
• Soundmap
• Volunteered Geographic Information (VGI)

Further reading

• Fu, P., and J. Sun. 2010. Web GIS: Principles and Applications. ESRI Press. Redlands, CA. ISBN 1-58948-245-X.
• Graham, M. 2010. Neogeography and the Palimpsests of Place. Tijdschrift voor Economische en Sociale Geografie. 101(4), 422-436.
• Kraak, Menno-Jan and Allan Brown (2001): Web Cartography – Developments and prospects, Taylor & Francis, New York, ISBN 0-7484-0869-X.
• Mitchell, Tyler (2005): Web Mapping Illustrated, O'Reilly, Sebastopol, 350 pages, ISBN 0-596-00865-1. This book discusses various Open Source Web Mapping projects and provides hints and tricks as well as examples.
• Peterson, Michael P. (ed.) (2003): Maps and the Internet, Elsevier, ISBN 0-08-044201-3.
• Rambaldi G, Chambers R., McCall M, And Fox J. 2006. Practical ethics for PGIS practitioners, facilitators, technology intermediaries and researchers. PLA 54:106-113, IIED, London, UK

External links

Sites

• UMN MapServer documentation and tutorials
• Webmapping with SVG, Postgis and UMN MapServer tutorials
• International Cartographic Association (ICA), the world body for mapping and GIScience professionals

Networks

• Open Forum on Participatory Geographic Information Systems and Technologies - a global network of PGIS/PPGIS practitioners with Spanish, Portuguese and French-speaking chapters.
• Geowanking