Mobile Geographic Services

David Maguire
Director of Products, ESRI Inc., USA
Infocity, Madhapur, Hyderabad – 500 035
dmaguire@esri.com


It seems that change is the only thing that is constant in the world of information and communication technologies. Just as the mainframe and minicomputers of the 1960s and 1970s, gave way to the workstations and personal computers of the 1980s and 1990s, another revolution is upon us. Stimulated by the need for an up to date geographically sensitive information, advances in hardware size, performance and power consumption, and improvements in network bandwidth, a new breed of mobile geographic applications is being developed that promise to change forever the way we use geography in home and professional life.

Mobile geographic applications are characterised by their ability to support itinerant, distributed and ubiquitous computing.
  • Itinerant - providing computing capability while moving with a person, in a vehicle, or on an aircraft or ship
  • Distributed -integrating functions that are performed at different places in a way that is transparent to the user
  • Ubiquitous - delivering the same functionality independent of a user’s location.
The term ‘location-based services’ has been suggested recently to describe this new suite of geographic information system (GIS) applications. In these applications geographic data and processing are provided as a type of service over a wireless network connection. This means that simple, low powered devices, such as pagers and mobile phones can now take advantage of geography. The term ‘mobile geographic services’ is preferred here because of its wider definition and focus on geography and GIS.


Fig. 1: Key elements of mobile GIS


Geographic services
In this context a service is a server-based application that delivers data and/or processing to clients on demand. Geographic services receive requests from clients (pagers, phones, Pocket PCs, PCs, etc.) for geographic data and/or processing (e.g. make a map, geocode an address, download data for an area). The query, analysis and mapping operations are performed on the server, or in the case of more advanced clients, possible on the client as well as the server. In the either case the results are displayed on the client. The results could be a map, a list of geocoded addresses, or a data file. Services have a number of important properties: they are always available (subject to security and connectivity constraints), they can support lightweight clients, they can process multiple clients at the same time, they can scale to support large numbers of requests, by adding additional machines, and they can be maintained centrally in secure facilities by specially trained staff. An Internet web site that draws maps is an example of a simple geographic service. Service-based architectures are increasingly being used to build traditional enterprise and new mobile geographic applications.

Applications
Busy people who are frequently on the move and want to use their time efficiently are increasingly requesting access to geographically sensitive data and services. Good quality, up to date and timely geographic data and services enable a range of new mobile geographic applications. Examples include Mapping, Yellow pages , Routing , Tracking , Advertising, Variable tariffs , Data collection , Public safety, etc.


Fig. 2: ESRI ArcGIS architecture


Mobile GIS
A mobile geographic information system is not a conventional GIS modified to operate on a small computer such as a laptop. It is a system built using a fundamentally new paradigm based on the key elements shown in Figure 1.

Wireless network
Many methods of wireless communication are available for mobile geographic systems including radio communication, but commercial cellular telephone systems are increasingly preferred. The number of mobile phone users now exceeds 50% in many European and Asian countries (it is above 75% in both Finland and Norway1 ). There are several options available for low and high level communication over cellular telephone networks.


Fig. 3: ArcPad – mobile geographic software.


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