Global Positioning System Reference
In-Depth Information
communications (e.g., the GPRS service of GSM). The data thus collected is
known as “floating car data” or “probe data,” and in early experiments it was
found useful to use fleets of taxis that randomly “float” around a city. An
alternative, more controlled situation, can use buses to probe specific routes
regularly.
It is generally considered that if just a few percent of moving vehicles are
probing, a useful statistic is collected that can be fed back to drivers (via their
navigation units) to help them avoid traffic jams and thus improve the overall
traffic flow efficiency.
8.8.2
Calendars, Diaries, and Logistics
The movement of people can also be managed by a 4D map that can be
considered as part of an electronic diary or calendar. Already there is much static
groupware (i.e., collaborative software applications), for example the personal
calendar in Microsoft Outlook. If these are combined with a personal positioning
system, perhaps based on wire communication access (using WiFi hotspot or
cellular radio), and a GIS, maps can be made on demand to show where people
are located (with varying degrees of likelihood as the a priori nature of diary
entries is confirmed by physical measurements).
The logistics of physical objects of high significance can be treated in much
the same ways as for people, except rather than a calendar database there will be
custom enterprise software that performs the event processing wrapped up in
solutions associated with supply chain management such as stock control and
warehousing.
8.8.3
Event Processing
Overall, however, there is a need to converge all these locations and event
functions into an overall system of Whereness, so that the common functions of
4D mapping and event processing can benefit from economies of scale and
conform to an open standard.
An event engine can be added to systems using GIS, for example, a traffic
management system or a groupware calendar/whereabouts system. Both need to
generate events in the form of messages or software processes, in response to
specific temporal-spatial combinations. For example, a dispatcher may wish to
know when a specific truck has reached a way point to predict if a delivery will be
late or on time. A manager may wish to see if the planned meeting is viable given
the progress the attendees are making with their various routes and personal
schedules. A police department may wish to be alerted if an unusual traffic pattern
of vehicles or people is being detected that may be indicating a forthcoming crime
that could be as serious as an act of terrorism.
