CHAPTER 1 : Understanding Reality — From Physical to Virtual

Prof.(Dr.) D G Mahto, Founder & CEO -

CHAPTER 1

Understanding Reality — From Physical to Virtual**

1.1 Introduction to the Nature of Reality

Human beings perceive the world not as it truly is, but as our senses interpret it. What we call “reality” is constructed by our brain using signals from our eyes, ears, skin, and other sensory systems. These perceptions allow us to interact with the world—but they also have limitations. We see only certain wavelengths of light, hear only specific frequencies, and can process only a fraction of the sensory data around us.

This chapter explores how Extended Reality (XR) builds upon the boundaries of human perception by altering, supplementing, or simulating sensory input. Before we understand XR technologies, we must understand what “reality” means in the human context.

1.2 Human Perception: How We Sense Reality

1.2.1 Vision: The Dominant Sense

More than 70% of human sensory input is visual. Our eyes collect light, convert it into electrical signals, and send it to the brain’s visual cortex. However:

  • The field of view is limited.

  • Depth perception depends on binocular vision.

  • We cannot perceive very small, very large, or very fast-moving objects accurately.

XR technologies extend these limitations by offering wider fields of view, enhanced details, and spatially realistic environments.

1.2.2 Hearing: Understanding Sound in 3D

Humans localize sound using differences in timing and intensity between our ears. XR audio—often called spatial audio—mimics this by digitally placing sounds in three-dimensional space.

1.2.3 Touch, Balance, and Body Awareness

Other senses used in XR include:

  • Haptics for touch simulation

  • Proprioception for body position awareness

  • Vestibular system for balance

These senses are crucial for immersive realism and reducing motion sickness.

1.3 The Reality–Virtuality Continuum

A key framework for understanding XR is the Reality–Virtuality Continuum, proposed by Paul Milgram and Fumio Kishino.

Physical Reality  ←———→  Augmented Reality  ←———→  Mixed Reality  ←———→  Virtual Reality

1.3.1 Physical Reality

The real world, as perceived naturally.

1.3.2 Augmented Reality (AR)

Digital elements are overlaid onto the real world.
Examples:

  • Pokémon Go

  • Google ARCore

  • Microsoft HoloLens (limited AR mode)

1.3.3 Mixed Reality (MR)

Digital and physical objects interact in real time.
Examples:

  • HoloLens 2 holograms anchored to real surfaces

  • MR for industrial training

1.3.4 Virtual Reality (VR)

A fully immersive artificial environment that replaces physical surroundings.
Examples:

  • Meta Quest

  • HTC Vive

  • VR surgical simulators

Understanding this continuum is essential as XR applications often blend these states.

1.4 The Evolution of Virtual and Augmented Worlds

1.4.1 Early Attempts at Simulation

Before XR devices existed, humans simulated reality through:

  • Paintings

  • Panoramic murals

  • Optical illusions

  • Motion pictures

  • Early flight simulators

These formed the philosophical foundation of immersive technology.

1.4.2 The Birth of VR (1960s–1980s)

Key milestones include:

  • Sensorama (1962): Multi-sensory immersive booth

  • Sword of Damocles (1968): First head-mounted display

  • Early computer graphics experiments

1.4.3 The 1990s Boom and Crash

VR entered gaming arcades but failed commercially due to:

  • Low computing power

  • Poor graphics

  • Bulky headsets

1.4.4 The XR Renaissance (2010–Present)

The modern era transformed XR through:

  • Smartphone-level processors

  • Lightweight displays

  • High-resolution screens

  • Motion tracking systems

  • Affordable VR devices like Oculus Rift

Today, XR is used in education, design, medicine, engineering, and entertainment.

1.5 Why Humans Accept Virtual Worlds

1.5.1 Immersion

The technical ability of a system to deliver a convincing environment.

Factors include:

  • Field of view

  • Motion tracking accuracy

  • Visual fidelity

  • Refresh rate

  • Latency

1.5.2 Presence

The psychological feeling of “being there.”
Presence is influenced by:

  • Realistic physics

  • Responsive interactions

  • Spatial audio

  • Reduction of sensory conflict

1.5.3 The Sense of Agency

Users feel they control virtual actions.
This is critical for training, simulation, and gaming.

1.6 The Science Behind XR Display and Interaction

1.6.1 Displays

XR uses different display technologies:

  • LCD / OLED panels

  • MicroLED

  • Waveguides (for AR glasses)

  • Projection-based optics

1.6.2 Tracking Systems

Tracking enables the system to know:

  • Where the user is

  • How they are moving

  • What they are looking at

Types include:

  • Inside-out tracking (cameras on device)

  • Outside-in tracking (external sensors)

  • Marker-based tracking

  • SLAM (Simultaneous Localization and Mapping)

1.6.3 Interaction Models

Users interact through:

  • Controllers

  • Hand tracking

  • Eye tracking

  • Voice commands

  • Haptic gloves

  • Spatial gestures

1.7 The Role of Spatial Computing

Spatial computing is the backbone of XR. It enables devices to:

  • Understand the environment

  • Map surfaces and obstacles

  • Anchor objects in physical space

  • Recognize gestures

  • Enable multi-user shared spaces

Companies like Apple (Vision Pro), Meta, and Microsoft lead in this domain.

1.8 Benefits of XR: Why It Matters

1.8.1 Learning and Education

  • Concept visualization

  • Immersive classrooms

  • Virtual field trips

1.8.2 Industry and Manufacturing

  • Digital twins

  • Assembly training

  • Remote maintenance

1.8.3 Medicine and Healthcare

  • Surgical training

  • Patient therapy

  • Medical imaging overlays

1.8.4 Entertainment and Social XR

  • Gaming

  • Virtual concerts

  • Social VR platforms

1.8.5 Architecture and Design

  • Virtual walkthroughs

  • Real-time modelling

1.9 Challenges in Perception and Cognition

1.9.1 Motion Sickness

Occurs when sensory systems disagree.

1.9.2 Cognitive Overload

Too much information can reduce usability.

1.9.3 Physical Fatigue

Standing or wearing heavy headsets for long durations.

These challenges push XR designers to focus more on ergonomics and user comfort.

1.10 Conclusion of Chapter 1

Understanding reality is the foundation of understanding Extended Reality. This chapter built the conceptual base by exploring how humans perceive the world and how XR manipulates or extends that perception.

Key takeaways include:

  • Reality is subjective and shaped by sensory interpretation.

  • XR lies on a continuum from physical to fully virtual environments.

  • Human psychology plays a crucial role in immersion and presence.

  • Spatial computing, displays, and tracking systems define the technical backbone.

  • XR offers transformative potential across industries but also presents cognitive and ergonomic challenges.

In the next chapter, we will move deeper into the technical components underpinning XR devices.

Prof. (Dr.) D. G. Mahto: A Visionary Director, Professor, Leader & Educator With over 25 years of excellence, Prof. (Dr.) D. G. Mahto is a Director, Professor, Philanthropist, HEI Builder, writer, consultant, reviewer, and career advisor at "Career Education for Success—Discover, Apply, Succeed!" He has empowered individuals, brands, and institutions through insightful content, innovation, and mentorship. Holding a Ph.D. in Engineering from NIT Jamshedpur, he has pursued Post-Doctoral Programs at IITs, NITs, and IIITs, reinforcing his expertise. A member of prestigious global organizations like NPA (USA), IET (UK), ASME, IAENG, and MRSI, he actively contributes to engineering, research, and education. An accomplished writer and researcher, he shares knowledge via Career Education Success Now, Career Edus, and Discover Knowledge Wisely. His vision integrates technology, innovation, and leadership, bridging gaps between aspirations and achievements. Connect with him for insights into education, research, and professional growth.

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