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1.2.1. Types of Geographic Information

Background and Foreground

Most location based services will consist of a mixture of two general types of information; Background and Foreground Information.

Background

Background information describes the geographical setting for users’ activities. It is used for orientation and provide a framework for integrating the special purpose, foreground, information. Generally, background information is static, appropriate to many different activities and ready to use without much alteration. It is usually obtained from map product agencies (e.g. National Mapping Agencies). Typical background information includes; topographic base maps, land-cover, satellite imagery and aerial photographs.

Foreground

Foreground information is more special purpose information that will be dynamically filtered and adapted to suit a users’ interests and context. Generally, it is provided by information service providers as feeds of raw data, for example 'yellow-pages' providers. As such, it needs to be processed to integrate it within an application, for example, so that it can be displayed on a background map. Typical foreground information includes; points-of-interest, services of interest and driving restrictions information. The animation shows examples of different types of foreground and background data used in LBS.

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Examples of Content

Background Data

Base mapping – topographic vector and raster data sets over a range of scales. They include; road networks, railways, building outlines, elevation data and administrative boundaries.
Imagery - satellite, aerial and terrestrial imagery for visualisation.


Foreground Data

Points-of-interest - various categories of prominent places and landmarks (with attributes)
Services-of-interest - geocoded electronic yellow pages / business directory with detailed attributes of each service including URL links to Web pages.
Navigation data - public transport routes, street-level routing data including one-way systems, driving restrictions (e.g. no entry), key signs and other road furniture such as traffic lights and bus stops.
Sound clips - such as commentaries on features of interest and prerecorded navigation instructions.
Moving image clips - for example from Web-cams


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