5.1. Classifification of technology characteristics and major challenges
5.1.1. State-of-the-art studies of VR/AR technologies
A VR/AR system is typically referred to hardware components,
Fig. 5.Number of VR/AR-CS Papers Published in the Selected Journals.
Fig. 6.Number of VR/AR-CS papers distributed in the difffferent countries/regions.
Automation in Construction 86 (2018) 150–162
153software, and algorithms. Hardware incorporates a processor, display,
sensors and input/output devices, and software and algorithms refer to
the main measures regarding how realistically a VR/AR scenario can be
achieved, the input devices (taxonomy is created asFig. 8) are the
means by which the user interacts with the virtual world[31]. They
send signals to the system about the action of the user, so as to provide
appropriate reactions back to the user through the output devices
(taxonomy is created asFig. 9) in real time[32]. The computer with
VR/AR engine handles the interaction with users and serves as an in
terface with the Input/Output (I/O) devices. For example, the more
processing power and a powerful graphics accelerator or distributed
computer systems interconnected through high-speed communication
network could make the calculating and generate graphical models,
object rendering, lighting, mapping, texturing, simulation and display
in real-time[15]. VR/AR system software is a collection of tools and
software for designing, developing and maintaining augmented or
virtual environments and the database where the information is stored
[33]. The VR/AR system could be confifigured or selected according to
the requirement of the application in construction safety to achieve the
difffferent level of immersion or interaction[34].
According to the level of immersion derived from a varied combi
nation of hardware and software confifigurations, the reviewed articles
can be further divided into seven categories (Table 1). Least-immersive
VR systems, also called Desktop VR system, Fish tank or Window on
World system is the least immersive and least expensive of the VR
systems, as it requires the least sophisticated components[35]. Its ap
plication areas in VR/AR-CS include education and training. Semi-Im
mersive VR system, also called hybrid systems, provides a high level of
immersion while keeping the simplicity of the desktop VR or utilizing
some physical model. An example of such system includes the CAVE
(Cave Automatic Virtual Environment), and an application is the crane
simulator[36]. Interestingly, full-immersive VR system takes an only
Fig. 7.VR/AR-CS review taxonomy.
Fig. 8.A Taxonomy of VR/AR Input Devices.
Automation in Construction 86 (2018) 150–162
154proportion of 6.7% in VR/AR-CS, on the other hand, it is the most
expensive and gives the highest level of immersion to give the user the
feeling of being part of the virtual environment. One of its applications
is in virtual walk-through of the construction site to recognize hazards
[6]. The tangible AR system (account for 32%) is widely applied in VR/
AR-CS particular in the process of inspection and instruction, which
objects in the real world are used as AR interface elements, and their
manipulation is used for interacting with virtual contents[37]. 4.5%
and 5.5% of the VR/AR-CS studies focused on collaborative AR and
distributed-VR/AR respectively. This number is reasonable and not
surprising, considering these two technology categories are emerging in
construction safety. In collaborative AR, users share space that contains
both real and virtual objects[38]. In this way, the interactions are not
only between a user and the AR system but are also among users.
Distributed-VR/AR also called Networked-VR/AR, which exists as a
result of rapid development of the internet. Its goal is to remove the
problem of distance, allowing people from many difffferent locations to
participate and interact in the same virtual world through the help of
the internet and other networks[39].
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