on October 21, 2006 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 (
CD,
DVD, etc.), 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 (
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. 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 (e.g. due to
color blindness). 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. ==History==