Maps and Whereness - Ubiquitous Positioning - page 152

8.7.4 Agencies to Validate and Verify
It is not clear yet exactly how the mapping and ICT industry, and governments
will be dealing with the need to control open mapping. It seems reasonable to
suppose that industry groups will to an extent self-regulate but given the strategic
importance of reliable mapping it is likely that governments will see the need to
be active (as we saw in the section above). Although open mapping may be free,
there may be other versions of the same maps that have been checked where a fee
is payable (to cover the costs of checking). Organizations with trusted brands will
be prime candidates to perform this function which may become the main role for
today's traditional mapmakers.
These organizations may actually start to promote open mapping and
crowdsourcing as a cheap way to get an area mapped (and remapped regularly,
since it is the changes to maps—their maintenance—that is expensive). The quid
pro quo is that the free maps will be hosted and available for all in a verified and
validated form for mission-critical applications.
8.8 4D Maps and the Temporal Dimension
Dynamic information concerns things that are changing rapidly with respect to
time. Adding dynamic geospatial information to static maps was discussed in
Section 4.2. A spatial map may have three dimensions but the addition of time
adds a further dimension. For example, adding to each road link on the map its
real-time road congestion (as an impedance factor) allows a computer to calculate
not just the shortest route but the quickest route. Another transport example would
be the progress of a specific vehicle along a route that could be displayed as a
moving image overlay to the static map which remains stationary on a screen. A
good example of a dynamic map is Traffic England [2], where the U.K. Highways
Agency links the Web map of the U.K.'s main routes to the highway traffic
sensors and the messages displayed on the roadside variable message signs. The
map changes in real time (minute by minute) as the various events unfold. The
M25 motorway around London is one of the most congested roads and its
problems at busy times (i.e., most of the working day) result in large amounts of
dynamic information.
8.8.1 Floating Car Data
To map the dynamic state of vehicle congestion on roads it is necessary to sense
the traffic flow. Many types of stationary traffic sensors are used, including
inductive loops beneath the road surface, optical cameras, and infrared detectors
mounted above the road, but the most efficient option is to use the vehicles
themselves. If fitted with a GPS unit or other positioning system, the vehicle
becomes a sensor that can report dynamically in real time using mobile