The expansion to extended reality (XR

iii. Sensory Feedback. VR, in order to fully transmit a sense of immersion, requires to simulate all

senses and provide sensory feedback from actions. Adequate stimuli such as a proper sound can

stimulate certain responses or feedbacks.

iv. Interactivity. Interactivity refers to the degree of information and data exchange in the virtual

world and to the amount of involvement of the user in experiencing and exchanging in the

virtual world. Involvement is related to the ability to act and transform the environment which

enhance the virtual experience. In virtual reality, audience can navigate through space, travel the

virtual world, change the point of view, communicate and exchange information but also

interact with objects found in the environment, selecting them, move and manipulate their

state.

Figure 92 Factors that create a vivid virtual experience

The expansion to extended reality (XR)

Virtual reality systems are categorized based on three main characteristics: Interactivity, 3d spatial

model, real-time – feedback. In the recent years, due to the increase of computer graphics processing

performance, VR is moving to an extended reality form such as virtual reality (VR), mixed reality (MR)

and augmented reality (AR), augmented vitality (AV) etc. They are exploring the frontiers of innovation

regarding the interactive level. In fact, in addition to the basic forms of VR, they combine together the

virtual and the real environment and develop response, which mean that the system either virtual or real

responds to the user. Mobile location-based devices for example can show people bus timetables in real

time. The most basic virtual reality representations were linked to 360-degree video. These are video

recordings with a spherical camera that allows a view in multiple directions. 360 videos can be videos on

the real environment (cinematography or videography), or animation captures from a 3D model), or

both. They can run on game engines and can be seen through headset. Nowadays virtual space can be

rebuilding through detailed 3D models and explored in a variety of forms, being connected also to the

real world. In this regard, Milgram et al, (1994) claimed a Reality-Virtuality Continuum and identifies

different types of virtual reality such as: AR, AV, VR, XR.

- Augmented reality AR

Augmented reality is a semi-immersive experience that allows to overlay virtual objects over the physical

environment (Fischer et al., 2006) delivered via technical device such as a mobile phone, live camera or AR glasses. This data can be 2D images, 3D graphics/models, text, information etc. Technology allows to

sense proprieties and data from the virtual world and to use them in real-time, enriching the real world

experience. In AR, the system provides information or data to the user in real time, meaning that it is

related directly with his current experience. Azumaet al. (2001) highlighted three main characteristics of

an augmented reality (AR):

Figure 93 Milgram’s Reality-Virtuality Continuum concept (Milgram and Kishino, 1994)

1. the combination of real and virtual objects in a real world;

2. real time processing,

3. the align of real and virtual objects with each other.

A classic example is the train timetable updated by tracking user’s location. Augmented reality is based on real environment elements tracking, which are than synchronised with a model or data in 3D virtual

environment.

Moreover, multisensory interactions are possible through devicesattached to the body (helmets, gloves, sensors, chips, Force Balls/Tracking Balls, Controller Wands, Trackpads, Motion Trackers/Bodysuits,

smart lenses, AR glasses, Motion Platforms etc.) and the room or CAVE(Cave Automated Virtual

Environment.

- Mixed-reality

Mixed – reality is a combination of Virtual Environment, virtual reality and Real World. According to Milgram & Kishino (1994), mix reality incorporates AR in terms of a “mix of real and virtual objects within

a single display.” It lets you to see the real world on one side and an imaginary environment on the

other, linking the two worlds. However, it differs as AR is a navigation environment while MR has the

possibility to manipulate the environment in real time. Milgram et al. (1995) proposed the concept of

Reality-Virtuality Continuum. The five senses of reality can be included in MR in order to make it more