Web mapping


Web mapping or an online mapping is the process of using, creating, and distributing maps on the World Wide Web, usually through the use of Web geographic information systems. A web map or an online map is both served and consumed, thus, web mapping is more than just web cartography, it is an interactive service where consumers may choose what the map will show.

Introduction

The advent of web mapping can be regarded as a major new trend in cartography. Until recently, cartography was restricted to a few companies, institutes and mapping agencies, requiring relatively expensive and complex hardware and software as well as skilled cartographers and geomatics engineers.
Web mapping has brought many geographical datasets, including free ones generated by OpenStreetMap and proprietary datasets owned by Baidu, Google, HERE, TomTom, and others. A range of free software to generate maps has also been conceived and implemented alongside proprietary tools like ArcGIS. As a result, the barrier to entry for serving maps on the web has been lowered.
The terms web GIS and web mapping are often used interchangeably, but the terms are distinct. Web GIS uses and enables web maps, and end users who are web mapping are gaining analytical capabilities from Web GIS, however Web GIS has more applications than web mapping, and web mapping can be accomplished without Web GIS. Web GIS emphasizes geodata processing aspects more involved with design aspects such as data acquisition and server software architecture such as data storage and algorithms, than it does the end-user reports themselves. The term location-based services refers to web mapping consumer goods and services. Web mapping usually involves a web browser or other user agent capable of client-server interactions. Questions of quality, usability, social benefits, and legal constraints are driving its evolution.

Types

A first classification of web maps has been made by Kraak in 2001. He distinguished static and dynamic web maps and further distinguished interactive and view only web maps. Today there is an increased number of dynamic web maps types, and static web map sources.

Analytical web maps

Analytical web maps offer GIS analysis. The geodata can be a static provision, or need updates. The borderline between analytical web maps and web GIS is fuzzy. Parts of the analysis can be carried out by the GIS geodata server. As web clients gain capabilities processing is distributed.

Animated and realtime

Realtime maps show the situation of a phenomenon in close to realtime. They are usually animated. Data is collected by sensors and the maps are generated or updated at regular intervals or on demand.
Animated maps show changes in the map over time by animating one of the graphical or temporal variables. Technologies enabling client-side display of animated web maps include scalable vector graphics, Adobe Flash, Java, QuickTime, and others. Web maps with real-time animation include weather maps, traffic congestion maps and vehicle monitoring systems.
CartoDB launched an open source library, Torque, which enables the creation of dynamic animated maps with millions of records. Twitter uses this technology to create maps to reflect how users reacted to news and events worldwide.

Collaborative web maps

are a developing potential. In proprietary or open source collaborative software, users collaborate to create and improve the web mapping experience. This type of web mapping is the most popular or familiar amongst the population today. Some collaborative web mapping projects are:
  • Google Map Maker
  • Here Map Creator
  • OpenStreetMap
  • WikiMapia
  • meta:Maps - a survey of Wikimedia movement web mapping proposals

    Online atlases

Online atlases are collections of maps in a specific period of  time like general reference maps, thematic maps, and geographical information. The traditional atlas goes through a remarkably large transition when hosted on the web. Atlases can cease their printed editions or offer printing on demand. Some atlases also offer raw data downloads of the underlying geospatial data sources.

Static web maps

Static web pages are view only without animation or interactivity. These maps were often used before technological advancements allowed the user to interact. These files are created once, often manually, and infrequently updated. Typical graphics formats for static web maps are PNG, JPEG, GIF, or TIFF for raster files, SVG, PDF or SWF for vector files. These include scanned paper maps not 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.

Web GIS in the cloud

Various companies now offer web mapping as a cloud based software as a service. These service providers allow users to create and share maps by uploading data to their servers. The maps are created either by using an in browser editor or writing scripts that leverage the service providers API's.

Advantages of mapping software

Compared to traditional techniques, mapping software has many advantages. The disadvantages are also stated.
  • Web maps can easily deliver up to date information. If maps are generated automatically from databases, they can display information in almost realtime. They do not need to be printed, mastered and distributed. Examples:
  • * A map displaying election results, as soon as the election results become available.
  • * A traffic congestion map 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. Geodata, on the other hand, is not; satellites and fleets of automobiles use expensive equipment to collect the information on an ongoing basis. Perhaps owing to this, many people are still reluctant to publish geodata, especially in places where geodata are expensive. They fear copyright infringements by other people using their data without proper requests for permission.
  • 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, a map update takes 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 occur more often. Perhaps owing to this, many web maps are of poor quality, both in symbolization, content and data accuracy.
  • Web maps can combine distributed data sources. Using open standards and documented APIs one can integrate 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. In addition, 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.
  • 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 cannot easily distinguish. Despite this, as with paper, web maps have the problem of limited screen space, but more so. This is in particular a problem for mobile web maps; the equipment carried usually has a very small screen, making it less likely that there is room for personalisation.
  • Web maps enable collaborative mapping similar to 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, and 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.
  • 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. However, development of web maps is complicated enough as it is: Despite the increasing availability of free and commercial tools to create web mapping and web GIS applications, it is still a more complex task to create interactive web maps than to typeset and print images. Many technologies, modules, services and data sources have to be mastered and integrated. The development and debugging environments of a conglomerate of different web technologies is still awkward and uncomfortable.