# Development of a Virtual Reality Tool for Train Crew Training
## 2 Literature Review  
### Immersive Virtual Reality (IVR)  
Virtual reality is an artificially created digital environment, and its task is to reproduce real life. Two attributes characterize this environment:  
1. \"immersion\"--means an objective level of sensory fidelity that a VR system provides [11];
2. \"presence\"--refers to the user's subjective experience resulting from being in the immersive environment [12]. However, some authors (e.g., [13; 14]) indicate that one more attribute should be added to the basic features of VR technology--\"interactivity\", which Steuer [15] defined as the degree to which a user can modify the VR environment in real time. The level of immersion determines the extent to which high-fidelity physical stimuli (e.g., light patterns, sound waves) are delivered to various senses (sight, hearing, and touch) to enhance the illusion of reality [16]. For this reason, in many publications, VR technology is divided into two major types based on the level of interaction and immersive environment [16; 17; 18]: (1) non-immersive virtual environment (desktop VR) and (2) immersive virtual environment (IVE). In a non-immersive virtual environment, the training simulation is presented on a conventional personal computer and is typically explored using a keyboard, mouse, wand, joystick, or touchscreen. This is the simplest type of virtual reality application. The training is presented on multiple room-size screens or a stereoscopic, head-mounted display unit in an immersive virtual environment. Audio, haptic, and sensory interfaces may enhance these systems. In his research, [PERSON] distinguished the third group of VR technologies, which is an intermediate between the abovementioned groups. He referred to it as semi-immersive (fish tank VR) systems [16]. These systems support head tracking and improve the feeling of \"being there\" thanks to the motion parallax effect. They still use a conventional monitor but generally do not support sensory output. The \"Immersive training system for railway personnel using virtual reality technology\" project aims to develop training solutions using IVR technology. IVR tools provide a seamless, scalable environment capable of simulating a full range of sensory stimuli and allowing the user to experience 360\({}^{\circ}\) visual immersion and manipulate virtual objects in real time [18; 19]. For this reason, some authors emphasize that the three main features provided by IVR are as follows [11]: the sense of immersion, real-time interaction, and imagination. IVR in the training system allows isolating the participant from external cues and uncontrolled stimuli from his/her physical word. This allows the participant to experience immersive and interactive scenery and interact with objects and tools in a desirable manner [20]. However, attention should be paid to the results of studies by [PERSON] et al. [21], according to which learners with certain individual traits and characteristics will benefit less from learning in VR (e.g., people with more anxious or reserved personalities). In their research, [PERSON] and [PERSON] [12] proved that immersive HMD learners were more engaged; spent more time on learning tasks; and acquired better cognitive, psychomotor, and affective skills. However, they also noted that the graphical quality of VR and the awareness when using VR, for instance, can reduce the sense of presence. Some authors classify the phenomenon of immersion used in VR solutions. Two classifications presented in Figure 2 deserve attention here. [PERSON] distinguished three dimensions of immersion in his research: tactical, strategic, and narrative immersion. A similar classification was proposed by [PERSON] and [PERSON], who used the term sensory-motoric, cognitive, and emotional immersion for analogous dimensions.