Ubiquitous User Localization for Pervasive Context-Aware Construction Applications - Mobile and Pervasive Computing in Construction - page 88

(PDR) system, and a hybrid tracking system, the Integrated Tracking System (ITS),
which integrates the GPS and the PDR localization systems to seamlessly transition
between GPS available and GPS denied environments. In addition to position and
head orientation tracking, monitoring eye motion or gaze tracking also offer several
possibilities to refine a user's spatial context. However, due to the relatively nascent
stages of development they are in, these latter technologies are not considered in
this chapter.
The developed methods and the components of the localization systems for
pervasive context-aware computing applications have been validated through
several experiments conducted at the University of Michigan, the National Institute
of Standards and Technology (NIST), and the Disaster City urban search and rescue
test bed in Texas.

6.2 Current state of knowledge

In early years, the human-computer interface was dominated by the prevalence of
so-called standard peripheral input devices, such as keyboards, mice, trackballs,
light pens and two/three-axis joysticks, in addition to some other forms of input
system,suchasthegraphicstablet,touchscreenor,insomecases,speech
recognition. However, a recent surge of interest in using computers for real-
time applications that require using input devices in six degrees of freedom
(DOF), namely the Cartesian translation in x, y and z, and Euler orientation in
roll, pitch and yaw, hasmanifested the inadequacies of using traditional computer
peripherals.
Examples of applications requiring accurate six-DOF input include robotics
(Cleary and Brooks, 1993), computer-aided design (CAD) (Barbi c and James,

2007), biomechanic analysis for the instrumentation of the human body (Aranov
et al ., 2004), military applications, such as in-cockpit head tracking (Lu et al ., 2002),
digital antique cataloguing, and archaeological site surveys, for the rapid pro-
duction of digital records of everything from temporarily uncovered sites to
preserved bodies.
In the field of construction specifically, all prior applications have been based on
exclusively using location-aware tracking systems that only provide the position of
mobile users (Aziz et al ., 2005). The three dimensional head orientation has been
ignored in the computations. To automatically provide constructors, engineers,
inspectors, and other field users with accurate prioritized contextual information
for critical decision making, six-DOF tracking details obtained from both position
and head orientation tracking systems are needed.
The position (i.e. location) of users is an important component of mobile
computing that can assist users with their desired goals, andmake the workplace
more intelligent. One of the most popular research areas in pervasive computing
is the development of location-aware systems. Location-aware techniques,
also called positioning technologies, are systems in which computing devices
provide the users with specific information depending on their location and