Distributed GIS - Web Mapping Services

Web Mapping Services

A web mapping service is a means of displaying and interacting with maps on the Web. The first web mapping service was the Xerox PARC Map Viewer built in 1993 and decommissioned in 2000.

There have been 3 generations of web map service. The first generation was from 1993 onwards and consisted of simple image maps which had a single click function. The second generation was from 1996 onwards and still used image maps the one click function. However, they also had zoom and pan capabilities (although slow) and could be customised through the use of the URL API. The third generation was from 1998 onwards and were the first to include slippy maps. They utilise AJAX technology which enables seamless panning and zooming. They are customisable using the URL API and can have extended functionality programmed in using the DOM.

Web map services are based on the concept of the image map whereby this defines the area overlaying an image (e.g. GIF). An image map can be processed client or server side. As functionality is built into the web server, performance is good. Image maps can be dynamic. When image maps are used for geographic purposes, the co-ordinate system must be transformed to the geographical origin to conform to the geographical standard of having the origin at the bottom left corner.

Web maps are used for location based services.

Examples of web mapping services are:

• Streetmaps
• Google Maps
• Multimap