i

SPECIAL STUDY ON VIRUAL REALITY TECHNOLOGY: VIRTUAL

REALITY HEAD-MOUNTED DISPLAY AND INTERACTION DEVICE

by

Sra Sontisirkit

Examination Committee: Prof. Sumanta Guha

Dr. Matthew N. Dailey

Dr. Raphael Duboz

Nationality: Thai

Previous Degree: Master of Computer Science

Asian Institute of Technology, Thailand

Asian Institute of Technology

School of Engineering and Technology

Thailand

August 2014

ii

TABLE OF CONTENTS

Chapter Title Page

Title Page i

Table of Contents ii

List of Figures iii

List of Tables iv

1 Introduction 1

1.1 Background 1

1.2 Problem Statement 1

1.3 Objectives 1

2 Literature Review 2

2.1 What is Virtual Reality? 2

2.2 History of Virtual Reality Technology 3

2.3 Definition of immersion and presences in virtual reality 5

2.4 Virtual reality display 6

2.4.1 Visual display 6

2.4.2 Audio display 7

2.4.3 Haptic display 8

2.4.4 Vestibular display 9

2.4.5 Other display 9

2.5 Present Technology 10

2.5.1 Head Mounted Display Technology in 2010s for Virtual reality 10

2.5.2 Interaction Technology 11

2.6 Virtual reality for learning/training system 13

2.7 Developing interactive virtual reality with Oculus rift DK2 and Leap

motion controller.

14

2.7.1 Hardware Specification 14

2.7.2 Software Specification 14

3 Conclusions and Future works 16

3.1 Objectives Review 16

3.2 Conclusions 16

3.3 Future works 17

References 18

iii

LIST OF FIGURES

Figure Title Page

2.1 4DX Theatre: the theatre can stimulate wind, bubbles, strobe light, fog,

scent, and vibration, short bursts of sharp air, face water and 3D display

2

2.2 A Holmes stereoscope and a Stereo card of a stereoscope 3

2.3 A poster of the Sensorama machin and Stereoscopic-Television Apparatus

for Individual Use that developed by Morton Heilig.

3

2.4 Interactive computer graphics with his Sketchpad application and the

Ultimate Display that invented by Ivan Sutherland.

4

2.5 The structure of the CAVE and the sample CAVE application 4

2.6 The PHANTOM Desktop Device and the PHANTOM Omni Device 5

2.7 Human-Virtual Environment interaction loop 5

2.8 Difference of quality of display between Oculus rift DK1 and DK2 6

2.9 A taxonomy of spatial manipulation (from the operator’s perspective), or

of spatial hearing (from the listener’s perspective)

7

2.10 Audio rendering pipeline 8

2.11 The system architecture of Dental Skills Training Simulator that

developed by Dr. Phattanapon Rhienmora.

8

2.12 The 360° vestibular display flight simulator from FLY-Motion 9

2.13 Google Cardboard: virtual reality viewer 11

2.14 A visual gamepad in the Architecture Visualization demo created by

Viewport

12

2.15 Neurosurgery resident testing a brain surgery simulation and screenshot of

tumor-debulking training task

13

2.16 My interactive virtual reality system 14

2.17 Screenshot of my interactive virtual reality: The model viewer. 15

iv

LIST OF TABLES

Table Title Page

2.1 The 5 basic tastes and the chemical substances to generate taste 9

2.2 The list of head mounted displays in 2010s 10

2.3 The list of interaction device in 2010s 13

1

CHAPTER 1

INTRODUCTION

This chapter describes background, motivation of this special study and introduces

technologies that take part in the research area. The detailed technical background is given in

the chapter two.

1.1 Background

Now a day, people interact via digital media more and more. Virtual reality can represent in

many aspects of life: managing business, learning, entertainment, even sexual relationships.

The development in virtual reality technology are accelerating to ensure virtual experiences

will become more immersive by providing sensory information that makes people feel they

are “inside” virtual environment. In few years ago, there are many companies have developed

low cost head mounted displays, motion capture devices and haptic displays. This allow more

developers and researchers can afford to build their own virtual reality system.

1.2 Problem Statement

Even though virtual reality devices are cheaper than 2000s, developing a virtual reality

system are very hard because developer need to understand the architecture of virtual reality

system and select the proper tools and devices for specific task. So this report guidelines the

basic of developing virtual reality system.

1.3 Objective

● To understand the concept of virtual reality.

● To understand the architecture and display devices of virtual reality system .

● To observe technologies for developing virtual reality system.

● To understand the benefit of using virtual reality in educational.

● To understand how to develop virtual reality system with Unity3D, Oculus Rift and Leap

Motion Controller on Windows OS.

2

CHAPTER 2

LITERATURE REVIEW

This chapter describes the relevant literature and the algorithms that related to this special

study.

2.1 What is Virtual Reality?

There are many definition of Virtual Reality according to researchers and users point of

view [1, 2]. The definition of Virtual Reality that I agree with is “VR is a high end computer

interface that evolves real time simulation and interaction through multiple sensorial

channels. These sensorial modalities are visual, auditory, tactile, smell, taste and other

senses.”[3].

One important feature to make the system creating virtual environment as real as

possible with the real time interaction, which means that virtual reality system must able to

receive inputs from real world for changing the virtual environment continuously and

naturally.

Figure 2.1: 4DX Theatre: the theatre can stimulate wind, bubbles, strobe light, fog, scent, vibration, short

bursts of sharp air, face water and 3D display [4].

3

2.2 History of Virtual Reality Technology

Back to 1850s, Sr. Oliver Wendell Holmes created Holmes stereoscope that consisted

of two prismatic lenses and a wooden stand to hold the stereo card. Holmes stereoscope was

the most popular stereoscope during 19th

century [5].

In 1956, Morton Heilig developed Sensorama machine. The machine gave the player

the experience of riding a motorcycle on the streets of Brooklyn and it can simulate the wind

on player face, the vibration of the motorcycle seat, a 3D view, and even smells of the city. In

1960, Morton Heilig receives a U.S. Patent for the first Head-Mounted Display call

“Stereoscopic-Television Apparatus for Individual Use” [2].

Figure 2.2: A Holmes stereoscope and a Stereo card of a stereoscope [5].

Figure 2.3: A poster of the Sensorama machine[2] and Stereoscopic-Television Apparatus for Individual Use

that developed by Morton Heilig[6].

4

In 1963, Ivan Sutherland created interactive computer graphics with his Sketchpad

application. After 2 years, he created Head-Mounted Display call “the Ultimate Display” that

can tracking the user head and display 3D graphic.

In 1977, Thomas A. DeFanti and Daniel J. Sandin from the Electronic Visualization

Laboratory (EVL) at University of Illinois, Chicago, created the first wired glove call “Sayre

Glove” that use to generate inputs to receiver by capturing physical data such as bending of

fingers. In 1992, EVL created the virtual room call “CAVE”. Graphics are projected in stereo

onto three walls and the floor and viewed with active stereo glasses equipped with a location

sensor. When user move, the system will change the display according to user position in

real-time to achieve a fully immersive experience.

In 1993, The MIT student name Thomas Massie and Professor Kenneth Salisbury

developed low-cost force-display device call “PHANTOM”. Now they are SensAble

Technologies, Inc.

Figure 2.4: Interactive computer graphics with his Sketchpad application and the Ultimate Display that

invented by Ivan Sutherland[2].

Figure 2.5: The structure of the CAVE and the sample CAVE application [7].

5

2.3 Definition of immersion and presences in virtual reality

There are many research papers describe the definition of Immersion and Presences

[1, 2, 3, 9, 10, 11, 12]. Most of them refer presence to the subjective sensation of “being

there” experienced. So I can conclude that:

Immersion is a description of the capability of computer displays to deliver a virtual

environment to users.

Presence is a description of user’s subjective psychological response to a virtual

environment.

The figure 2.7 shows that components of immersion are limited to software and

hardware of the system. In another hand, different users can experience different levels of

presence with the same virtual reality system depending on life experience: memory, ability,

past experience, emotional stare, and other factor [2].

Figure 2.6: The PHANTOM Desktop Device and the PHANTOM Omni Device[8].

Presence

Figure 2.7: Human-Virtual Environment interaction loop [9].

sion are limited to display software and hardware

6

Interacting with a virtual environment is another key factor of a VR experience.

Virtual reality system must able capture inputs from users for changing the virtual

environment continuously such as the visual display of a virtual reality system respond to a

user's physical movement and simulate force back to the haptic device when user move the

tool to hit something in virtual environment.

2.4 Virtual reality display

There are 4 main displays in Virtual reality that are the big multiplier for immersion:

visual display, audio display, haptic display, vestibular display [2].

2.4.1 Visual display

Users are hard to feels “being there” if they cannot see things by their eyes. So most of

virtual reality systems are focus on visual display. Visual immersion has many factors [2, 13],

including:

Field of view (FOV): the size of the visual field (in degrees of visual angle) that can be

viewed instantaneously.

Field of regard (FOR): the total size of the visual field (in degrees of visual angle)

surrounding the user.

Pixel per inch (PPI): the measurement of the pixel density (resolution).

Stereoscopy: the display of two slightly offset images to each eye to provide an

additional depth cue.

Frame rate: represents how many images that rendered by system every second.

Refresh rate: represents how many images that reconstructed by visual display in every

second. Example, To display 24 frames per second on a TV with a 120hz refresh rate,

each frame is repeated 5 times every 24th of a second.

To render the realistic environment, the virtual reality system much as able to tracking the

position and rotation of user’s head for rendering images according to user’s eye view.

Figure 2.8: Difference of quality of display between Oculus rift DK1 (185 PPI) and DK2 (386 PPI)

[13].

7

2.4.2 Audio display

Sound is the very simple way to make listeners notice sense of place, something there,

something happening or will happen in virtual environment [15]. The high-quality sound can

help in creating a fascinating experience, even when the quality of the visual presentation is

lacking. 3-D sound has the advantage over vision in that virtual sound sources can be

synthesized to occur anywhere in the 360-degree space around a listener. Audio immersion

has many factors [17, 18, 19], including:

3D localization: the virtual reality system must able to tracking the position and

rotation of the listener; for example, sounds should get louder as the listener moves

nearer to the sound sources and sounds should generate from the same place in virtual

environment when the listener rotate his/her head.

Sound delivery method: Different audio channel will give a different sense of sound

such as 2, 2.1, 5.1 and 7.1 channels, or headphone.

Variety: Loops and repetitions of sound can be detected and perceived as unrealistic.

Creating sound that does not repeat at a rate perceived by the listener will improve the

immersion of the virtual reality system.

Figure 2.9: A taxonomy of spatial manipulation (from the operator’s perspective), or of spatial hearing

(from the listener’s perspective) [16].

8

2.4.3 Haptic display

Haptic display is device that stimulates the sense of touch to user. Now a day, we can

see a lot of haptic device in gaming industry such as a driving wheel joystick that has force

feedback, a vibration gamepad or even vibration mobile phone. There are many information

represented by haptic display include surface properties of object in virtual environment

including texture, temperature, shape, viscosity, friction, deformation, inertia and weight [2].

Moreover, haptic display allow user to feel the difference between hard and soft tissues

which very important in medical surgery applications.

Figure 2.10: Audio rendering pipeline [15].

Figure 2.11: The system architecture of Dental Skills Training Simulator that developed by Dr.

Phattanapon Rhienmora[20]. The system can simulate force back to haptic device when the user

moves the dental headpiece to hit tooth in simulator.

9

2.4.4 Vestibular display

The vestibular perceptual sense maintains balance. Vestibular display allows humans

sense equilibrium, acceleration, and orientation with respect to gravity in virtual environment.

There is a strong relationship between the visual and vestibular systems. Inconsistency

between vestibular and visual systems can lead to nausea and motion sickness [21].

Vestibular display is common in flight and driving simulation systems.

2.4.5 Other display

There are many of human perception that technology still in research such as smell

and taste. Olfactory (smell) display can easily achieve using vaporizer and it may increase

immersion of virtual reality system such as sense of smell to detect specific substances in

virtual environment [23, 24]. Taste display is very hard to create because it is a multi-modal

sensation composed of chemical substance, sound, smell and haptic sensations. Taste

perceived by the tongue can be synthesized from five basic tastes [25].

Basic taste Chemical substance

Sweet Sucrose

Sour Tartaric acid

Salty Sodium chloride

Bitter Quinine sulfate

Umami Sodium glutamate

Figure 2.12: The 360° vestibular display flight simulator from FLY-Motion [22].

Table 2.1: The 5 basic tastes and the chemical substances to generate taste [25].

10

2.5 Present Technology

2.5.1 Head Mounted Display Technology in 2010s for Virtual reality

There are more than one hundred devices of head-mounted displays in market since

1995 [26, 27, 28]. The table below shows the list of head mounted displays in 2010s. Some of

them are still in development phase.

Position Tracking = PT, Head Tracking = HT, Refresh Rate = RR, h= horizontal

Name Screen

Size

Resolution

Per Eye

PPI FOV

(h)

PT 360°

HT

Additional Price

(USD)

Releas

e Date

Wrap 1200DX-VR

[29] N/A 852×480 N/A 35° No Yes

Very light weight (85 grams) 600 2011

Silicon Micro

Display

ST1080[30]

0.74"x2 1920×1080 2976 39° No No

User Liquid crystal on

silicon (LCoS) display 799 Dec

2011

Carl Zeiss

Cinemizer[31] N/A 870×500 N/A 30° No Yes

Support iOS device 729

Nov

2012

Oculus Rift Dk1

[33] 7” 640x800 185 110° No Yes

Very high of FOV 300

Nov

2012

Sony

HMZ-T3W[32]

0.7"x2 1280×720 2,098 45° No Yes

Use Sony’s OLED and

semiconductor silicon drive

technologies

1,499 Oct

2013

Oculus Rift Dk2

[33] 5.7" 960×1080 386 100° Yes Yes

Use external camera for

position tracking 350

Aug

2014

ANTVR KIT [34] N/A 960×1080 N/A 100° Yes Yes

Use Wireless Home Display

Interface (WHDI) 270

Dec

2014

GLYPH [35] None 1280×720 N/A 45° No Yes

Use Micromirror display,

120hz refresh rate 499

Dec

2014

Samsung

Gear VR [36] 5.7" 1280×1440 515 96° No Yes

Run on Samsung Note 4 750+ 2015

castAR [37] N/A 1280×720 N/A 90° Yes Yes

Use Micro projector and

retro-reflective material 345 2015

Game Face Lab [38]

5.5" 1280×1440 534 N/A No Yes Use Nvidia TEGRA K1

Chip. N/A 2015

Totem [39] N/A 960×1080 N/A 90° Yes Yes

2 built-in 1080p cameras for

Augmented Reality 450 2015

Sony Morpheus

[40] 5." 960×1080 N/A 90° Yes Yes

Use external camera for

position tracking N/A 2015

The competition of head mounted displays in 2010s make the prices decrease

dramatically. This make more people interest in virtual reality because they can afford it. One

of the most successful product is Oculus Rift DK2, the Oculus company sold the device more

than one hundred thousand devices in 2014[41]. Now a day, dedicated graphic cards are able

to render graphic for very high resolution and very high detail of the virtual environment in

real time with acceptable frame rate such as NVIDIA GeForce® GTX™ 780.

Table 2.2: The list of head mounted displays in 2010s

11

Moreover, any high-end smart phone can transform into head mounted displays by

attaching the smartphone into a virtual reality viewer such as Google Cardboard[42]. Smart

phones have a 360° tracking feature by using accelerometer and gyroscope to calculate the

rotation angle of the mobile phone. In another hand, smart phone is lacking of position

tracking, so it needs an additional device to track the position of the smart phone.

2.5.2 Interaction Technology

The types of tasks that users might perform in any interactive system are specifically

identified by Foley et al [43] into six fundamental types of interaction tasks as:

Selection: Make a selection from a set of alternatives.

Position: Indicate a position on the display or in the virtual environment.

Orientation: Alter the orientation of an object in the virtual environment. For 2-D,

this might mean rotating an object to be heading north. In 3D, it could mean

controlling the pitch, roll, and yaw of an object in 3D virtual environment.

Path: Generate a path, which is a series of positions and orientations over time.

Quantify: Specify a value to quantify a measure, such as the height of an entity.

Text: Input a text string.

Virtual reality system must install appropriate interaction devices to allow users

complete the specific task with intuitive ways. The most common devices that we use to

interact with the virtual environment are mouse, keyboard and gamepad. In my opinion, these

basic devices may break presence because users will worry about the controller device that

they cannot see when they use head mounted display. Controller device in the real world

must also recreate in the virtual environment to make users believe that they control the same

device in both real and virtual world.

Figure 2.13: Google Cardboard: virtual reality viewer [42].

12

The next level of interaction device is motion capture device, the device that can

detect rotation and position of the user’s body or devices. This kind of device allows users to

manipulate virtual objects presented to them in virtual environment. Precision and accuracy

are most important issue that needs to be handling very well because lacking of precision and

accuracy will break sense of presence. There are many kinds of interaction devices. The table

below shows the list of interaction devices that I reviewed. I give a precision and accuracy of

each devices base on my own experiences and research works [3, 45, 46, 47, 48, 49, 50, 51,

52, 53, 54].

Precision and accuracy = P&A (Fair, Good, Excellent), DOF = degree of freedom

Name Body Part P&A Advantage/Disadvantage Price

(USD)

Releas

e Date

PHANTOM

Omni[8]

Hand Excellent Able to simulate force feedback, Six DOF

positional sensing/ Limited distance. 1,000 2005

CyberGrasp

[55]

Hand and finger Excellent

Able to simulate force feedback, Six DOF

positional sensing /Heavy N/A 2005

Novint

Falcon[56]

Hand Excellent Able to simulate force feedback, Three DOF

positional sensing/ Limited distance. 300

Jun

2006

Kinect[57] Arm, Body, Head

and Leg

Fair Use camera and infrared to track user body.

/Position the sensor between 60 cm and 180 cm. 100

Jun

2011

Razer

Hydra[58]

2 x Hand Excellent

Have 2 controllers for both hands, Six DOF

positional sensing/Wired 140

Jun

2011

Leap

Motion[59]

Hand and finger Good Use camera and infrared to track user hand &

finger/Position the sensor between 5 cm and 25

cm.

100 May

2012

IGS Glove[60] Hand and finger Excellent Using Inertial sensing technology. Three DOF

positional sensing N/A 2013

Sixense

Stem[61]

Arm, Body, Head,

Leg, Hand

Excellent Using electromagnetic motion tracking

technology. Six DOF sensing and wireless 300

Jul

2014

Control

VR[62]

Arm, Body, Head,

Leg, Hand & Finger

N/A Able to simulate force feedback to hand, Using

Inertial sensing technology. 600 2015

Figure 2.14: A visual gamepad in the Architecture Visualization demo created by Viewport[44].

13

PrioVR[63] Arm, Body, Head,

Leg, Hand

N/A Using Inertial sensing technology. Have 2

controllers for both hands. 429 2015

Cyberith

Virtualizer

[64]

Body and Leg N/A Able to track walk, run, couch, sit and jump

actions, Able to simulate vibration feedback to

feet / Very big device.

749 2015

Virtual reality system needs proper software to create the virtual environment. The

main objectives of software are: providing immersive scenery and user interface, analyzing

input data and producing a feed back in real-time. The software that can achieve all

objectives is game engine such as Unity3d, Unreal and Source engine.

2.6 Virtual reality for learning/training system

Virtual reality system has the potential to make a difference, to guild learners to new

knowledge, to motivate and encourage at every level of education. Veronica [65] gives the

following reasons to use virtual reality in education:

Providing new forms and methods of visualization: Virtual reality display allows

learners to observe visual objects that may not able to do like in the real world.

Motivating students: Virtual reality system allow learner to interact and work with

other learners which can encourage them to have interests in subject matter.

Simulating dangerous, expensive situations: Virtual reality system allow leaners to

experience difficult tasks that hard/expensive to do in real world such as electrical

teaching experiments [66].

Learning from expert: Virtual reality system allow expert to share their experience

to their students such as share their actions during doing a virtual surgery [67].

Figure 2.15: Neurosurgery resident testing a brain surgery simulation and screenshot of tumor-

debulking training task [68].

Table 2.3: The list of interaction device in 2010s.

14

2.7 Developing interactive virtual reality with Oculus rift DK2 and Leap motion

controller.

The first step of developing virtual reality system is gathering proper tools and

devices. The machine must powerful enough for rendering display and analyzing data in real

time.

2.7.1 Hardware Specification

Processor: Intel Core I7 2.7 GHz (8 CPUs)

Graphics: NVIDIA GeForce GTX 660 TI

Memory: 8GB DDR3 1600 MHz

Sound Card: DirectX-compatible

Display: Oculus Rift DK2

Position tracking: Oculus Rift DK2 camera

Controller: Leap motion controller

2.7.2 Software Specification

OS: Windows 7

DirectX: Version 11

Game Engine: Unity3D v4.5.3

Display Driver: Oculus Rift SDK v0.4.2

Controller Driver: Leap motion SDK v2.2.023475

The second step is implementing the virtual reality application base on hardware and

software limitation. I developed a simple virtual reality application that allow user to interact

with the model in scene such as rotate horizontally, rotate vertically, push and pull by swipe

his/her hand. The position tracker always keeps track movement and rotation of the user’s

head for updating the visual.

Leap

Motion Position

Tracking

Oculus Rift DK2

Head Mounted Display

Figure 2.16: My interactive virtual reality system.

15

Textbox below is a C# code for handling interaction tasks by using the start and end position

of a swipe gesture that captured by leap motion controller to calculate the direction of swipe

gesture.

void CheckSwipeDirection(Gesture gesture){ SwipeGesture swipeGesture = new SwipeGesture(gesture); float x_start = swipeGesture.StartPosition.x; float y_start = swipeGesture.StartPosition.y; float z_start = swipeGesture.StartPosition.z; float x_end = swipeGesture.Position.x; float y_end = swipeGesture.Position.y; float z_end = swipeGesture.Position.z; float x_dif = Mathf.Abs (x_start - x_end); float y_dif = Mathf.Abs (y_start - y_end); float z_dif = Mathf.Abs (z_start - z_end); bool isHorzizontal = Mathf.Abs (x_start - x_end) > Mathf.Abs (z_start - z_end); bool isHorzizontal_Y = y_dif > Mathf.Max (x_dif,z_dif); if (isHorzizontal_Y) { // Push or pull if (y_start < y_end) { pushObject(); } else { pullObject(); }

}else if (isHorzizontal) { // Horizontal rotation if (x_start < x_end) { rotateObjectToLeft(); } else { rotateObjectToRight(); } } else { // Vertical rotation if (z_start < z_end) { rotateObjectToDown(); }else{ rotateObjectToTop(); } } }

Figure 2.17: Screenshot of my interactive virtual reality: The model viewer.

16

CHAPTER 3

CONCLUSION AND FUTURE WORKS

3.1 Objectives Review

To understand the concept of virtual reality.

The section 2.3 explains the definition of immersion and presence. The core virtual reality is

to make users feel the virtual environment by using displays to derive feedback to them.

To understand the architecture and display devices of virtual reality system.

There are 4 main components virtual reality system: model, computer system, display device

and input devices. The section 2.4 explains the 4 virtual reality display devices: Visual

display, audio display, haptic display, vestibular display.

To observe technologies for developing virtual reality system.

Now a day, there are a lot of virtual reality device in the market. In section 2.5 showed the

lists of virtual reality device in 2010s.

To understand the benefit of using virtual reality in educational.

There are many benefits from using virtual reality in educational such as providing new

forms and methods of visualization, motivating students, learning from expert, and simulating

dangerous/expensive situation.

To understand how to develop virtual reality system with Unity3D, Oculus Rift and Leap

Motion Controller on Windows OS.

The section 2.7 showed the simple interactive virtual reality application by using Oculus Rift

and Leap Motion to interact with the visual object in scene.

3.2 Conclusion

Virtual reality system is very useful technology that could improve educational into the next

level as we can see from many advance virtual reality systems that use for training people

such as virtual neurosurgery simulation and virtual dentist simulation. I think in next 2 year

from now, Virtual reality will be wildly use in many industry: games, movies, educations. We

will see people have their own VR system at home or in any smart phone.

17

3.3 Future works

I plan to continue Dr. Phattanapon Rhienmora’s research, the Dental Skills Training

Simulator. The simulator still lacks of stereo vision which very important to virtual reality

system. Moreover, I plan to upgrade the force feedback simulation of the dental skills

training simulator. It should able to simulate force feedback from soft tissue around mouth

such as: cheek, tongue and gum.

.

18

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