Title
Sub Title
AuthorPublisher
Publication year
JtitleJaLC DOI
Abstract
Notes
Genre
URL

Research on Layered 3D Display System based on the combination of Transparent LCD and
Traditional LCD
熊, 迪(Xiong, Di)
小木, 哲朗(Ogi, Tetsuro)
慶應義塾大学大学院システムデザイン・マネジメント研究科
2014

修士学位論文. 2014年度システムエンジニアリング学 第156号
Thesis or Dissertation
https://koara.lib.keio.ac.jp/xoonips/modules/xoonips/detail.php?koara_id=KO40002001-000020140012

慶應義塾大学学術情報リポジトリ(KOARA)に掲載されているコンテンツの著作権は、それぞれの著作者、学会または出版社/発行者に帰属し、その権利は著作権法によって保護されています。引用にあたっては、著作権法を遵守してご利用ください。
The copyrights of content available on the KeiO Associated Repository of Academic resources (KOARA) belong to the respective authors, academic societies, or
publishers/issuers, and these rights are protected by the Japanese Copyright Act. When quoting the content, please follow the Japanese copyright act.

Powered by TCPDF (www.tcpdf.org)

Master’s Dissertation

2014

Research on Layered 3D Display System
based on the combination ofTransparent LCD and Traditional LCD
熊迪
Xiong Di(Student ID: 81234593)
Supervisor: Professor Ogi Tetsuro
September 2014

Graduate School of System Design and Management,
Keio University
Major in System Design and Management

Summary of Master’s Dissertation
Student
Xiong Di
Identification

81234593

Name
熊迪

NumberTitle:

Research on Layered 3D Display System based on the

combination of Transparent LCD and Traditional LCD
Abstract:
As computational power and the interest in 3D graphics have increased dramaticallyin recent years, 3D display technology has become an attractive field. Until now, there
have been several kinds of 3D display devices. However, some factors like additional
devices, complex structure and high cost have become the main reasons that why 3D
display is still not being widely popularized. Considering the problems of current 3D
display systems, we proposed and successfully built a new layered 3D display system
by combining the transparent LCD and the traditional LCD.
In this research, based on the special structure of our system, we put forward a

combination of two methods (motion parallax and Depth-fused 3D) to realize 3D
effect in our system. We made the experiments to prove the feasibility of the two
methods in our system. And we also gave an application example of Ukiyoe toevaluate the 3D performance of our system.
Keywords:
3D, Transparent LCD, Traditional LCD, motion parallax, Depth-fused 3D, Depth
perception
2

Table of contents
1

Introduction ........................................................................................................ 9
1.1

2

3

4

1.1.1

Summary of 3D display system ........................................................... 10

1.1.2

Problems of current 3D display system................................................ 15

1.2

Purpose ...................................................................................................... 16

1.3

Structure of this thesis ................................................................................ 16

Proposal ........................................................................................................... 18
2.1

Concept of this research ............................................................................. 18

2.2

Related research on layered 3D system ...................................................... 23

System building ................................................................................................ 26
3.1

Hardware design ........................................................................................ 26

3.2

Software design ......................................................................................... 29

Motion parallax (MP) experiment ..................................................................... 34
4.1

Experimental purpose (MP) ....................................................................... 34

4.2

Experimental principle (MP) ...................................................................... 34

4.3

Experimental procedure (MP) .................................................................... 36

4.3.1

Preparation (MP) ................................................................................. 36

4.3.2

Execution (MP) ................................................................................... 38

4.4
5

Background ................................................................................................. 9Experimental result (MP) ........................................................................... 39

Depth-Fused 3D (DFD) experiment .................................................................. 48
5.1

Experimental purpose (DFD) ..................................................................... 48

5.2

Experimental principle (DFD) .................................................................... 48

5.3

Experimental procedure (DFD) .................................................................. 50

5.3.1

Preparation (DFD)............................................................................... 503

5.3.2
5.4
6

Execution (DFD) ................................................................................. 53

Experimental result (DFD) ......................................................................... 54

Motion parallax and Depth-fused 3D experiment .............................................. 59
6.1

Experimental purpose (MP+DFD) ............................................................. 59

6.2

Experimental procedure (MP+DFD) .......................................................... 59

6.2.1

Preparation (MP+DFD) ....................................................................... 59

6.2.2

Execution (MP+DFD) ......................................................................... 61

6.3

Experimental result (MP+DFD) ................................................................. 61

7

Application example ......................................................................................... 64

8

Discussion ........................................................................................................ 73

9Conclusion ....................................................................................................... 75

Acknowledge .......................................................................................................... 76
Reference ................................................................................................................ 77
Conference attendance............................................................................................. 79
Appendix................................................................................................................. 80

4

List of figures
Fig.1-1:

3D Prospect on 3D Industry Applicable Fields .................................... 9

Fig.1-2:

Principle of glasses type 3D display system .......................................11

Fig.1-3:

Principle of non-glasses type 3D display system ............................... 13

Fig.1-4:

Principle of light source rotation type 3D display system .................. 14

Fig.1-5:

Principle of volumetric type 3D display system ................................ 14

Fig.1-6:

Principle of holography type 3D display system ............................... 15

Fig.2-1:

Image of Transparent LCD ............................................................... 18

Fig.2-2:

Transparent LCD market forecast ..................................................... 19

Fig.2-3:

Schematic diagram of layered 3D display system ............................. 20

Fig.2-4:

Special structure of our layered 3D display system ........................... 21

Fig.2-5:

Speculated effect of motion parallax in our layered 3D display system.................................................................................................................. 21
Fig.2-6:

Speculated effect of depth-fused 3D in our layered 3D display system.................................................................................................................. 22
Fig.2-7:

Speculated effect of motion parallax and depth-fused 3D in our system.................................................................................................................. 23
Fig.2-8:

Half-mirror type layered 3D display system...................................... 24

Fig.2-9:

Projection type layered 3D display system ........................................ 24

Fig.2-10:

Immaterial DFD display using two fog screens ............................... 25

Fig.3-1:

Real image of transparent LCD and traditional LCD ......................... 26

Fig.3-3:

Front view of our system .................................................................. 27

Fig.3-2:

Top view of our system..................................................................... 27

Fig.3-4:

Side view of our system.................................................................... 28

Fig.3-5:

Polarization phenomenon ................................................................. 28
5

Fig.3-6:

Measurement board .......................................................................... 29

Fig.3-7:

Parameters to set glFrustum .............................................................. 31

Fig.4-1:

Principle of motion parallax.............................................................. 35

Fig.4-2:

Schematic of motion parallax experiment ......................................... 36

Fig.4-3:

Scene of motion parallax experiment ................................................ 38

Fig.4-4:

Variance of data for 0cm (1LCD) ...................................................... 40

Fig.4-5:

Variance of data for 4cm (2LCD) ...................................................... 40

Fig.4-6:

Variance of data for 8cm (2LCD) ...................................................... 40

Fig.4-7:

Variance of data for 12cm (2LCD) .................................................... 41

Fig.4-8:

Contrast of setting depth and experimenters’ perceived depth (0cm,

1LCD) ....................................................................................................... 43
Fig.4-9:

Contrast of setting depth and experimenters’ perceived depth (4cm,2LCD) ....................................................................................................... 43
Fig.4-10: Contrast of setting depth and experimenters’ perceived depth (8cm,2LCD) ....................................................................................................... 44
Fig.4-11: Contrast of setting depth and experimenters’ perceived depth (12cm,
2LCD) ....................................................................................................... 44
Fig.4-12:

Contrast of the 4 situations in MP experiment ................................. 46

Fig.5-1:

Principle of DFD .............................................................................. 49

Fig.5-2:

Schematic of DFD experiment .......................................................... 50

Fig.5-3:

Final effect of color compensation .................................................... 52

Fig.5-4:

Scene of DFD experiment................................................................. 53

Fig.5-5:

Average result and variance of 10 people for the DFD experiment .... 54

Fig.5-6:

Regression curve of the data for the DFD experiment ....................... 55

Fig.5-7:

Result of the situation that the sum of luminance percentages is not
6

100%. ........................................................................................................ 56
Fig.6-1:

Schematic of MP+DFD experiment .................................................. 60

Fig.6-2:

Image of MP+DFD experiment ........................................................ 60

Fig.6-3:

Average result of 10 people for the MP+DFD experiment ................. 62

Fig.6-4:

Variance of the data for the MP+DFD experiment ............................ 63

Fig.7-1:

Separation of Ukiyoe ........................................................................ 65

Fig.7-2:

Schematic diagram of displaying 3D Ukiyoe in 2 LCDs ................... 66

Fig.7-3:

Schematic diagram of displaying 3D Ukiyoe in 1 LCD ..................... 67

Fig.7-4:

Real pictures of Ukiyoe in two situations .......................................... 68

Fig.7-5:

Result of Q1 ..................................................................................... 69

Fig.7-6:

Result of Q2 ..................................................................................... 70

Fig.7-7:

Result of Q3 ..................................................................................... 70

Fig.7-8:

Result of Q4 ..................................................................................... 71

Fig.8-1:

An idea to realize free viewpoint for our system in the future ........... 73

Fig.8-2:

Image of an advanced layered 3D display system ............................. 74

7

List of tables
Table. 3-1:

Speciafication contrast of transparent LCD and traditional LCD... 26

Table. 4-1:

Parameters of the objects we prepared to display .......................... 37

Table. 4-2:

Average results of 10 people for the MP experiment ..................... 39

Table. 4-3:

ANOVA for the data of MP experiment ........................................ 42

Table. 5-1:

Combinations of luminance for DFD experiment ......................... 51

Table. 5-2:

Color compensation table ............................................................. 52

Table. 5-3:

ANOVA for the data of DFD experiment ...................................... 55

Table. 5-4:

ANOVA the situation (sum of luminance percentages is not 100%).................................................................................................................. 57

8

1 Introduction
1.1 BackgroundAs computational power and the interest in 3D graphics have increased dramaticallyin recent years, 3D display technology has become an attractive field [Lee, 2009].
Compared with 2D display devices, 3D display devices are considered to be able toincrease the sense of reality significantly. They are also being highly expected to
improve the easiness and accuracy in the fields of remote control, design, medicalcare and so on.

Fig.1-1:

3D Prospect on 3D Industry Applicable Fields[Kim, 2010]9Until now, there have been already several kinds of 3D display devices. For example,
Glasses type （Anaglyph type, polarization type, time-division type…）: Observers
will wear 3D glasses and then different images will be showed into their left eye andright eye, which will trigger 3D Perspective [Ohkoshi, 1980]. Non-glasses type(parallax barrier type, lenticular lens type…): instead of using glasses, the display
surface will be covered by special structure which separates the light for left eye andright eye [Travis, 1997]. Depth-sampling and multiplexing type (light source rotation
type, volumetric type…): integrating multiple layers with different depth by special
mechanical structure. Holography: creating stereopsis of high quality by recording
and releasing the light [Gabor, 1948].
However, some factors like additional devices, complex structure and high cost havebecome the main reasons that why 3D display is still not being widely popularized.
Besides the impact of surprising and newness, it is still fairly difficult to apply the 3D
display into some industrial fields or even as a consumer product in normal life.

1.1.1 Summary of 3D display system
Here we make a brief summary of current main 3D display systems.

1.1.1.1 Glasses type

There are mainly 3 kinds of methods in glasses type. As figure1-2 shows that, they are10

anaglyph type, polarization type and time-division type.

Anaglyph typePolarization typeTime-division typeFig.1-2:

Principle of glasses type 3D display system[Source: Takada, 2007]
11

Glasses type is the most popular 3D display system now. It uses one of thephysiological characteristics of human beings called binocular disparity. Binoculardisparity refers to the difference in image location of an object seen by the left andright eyes, resulting from the eyes’ horizontal separation. The brain uses binoculardisparity to extract depth information from the two-dimensional retinal images instereopsis [Qian, 1997]. Observers will have to wear a pair of 3D glasses which canseparate the original images by color, polarization, or time. Through the 3D glasses,
different images into left and right eye will stimulate binocular disparity and thencreate stereopsis.

1.1.1.2 Non-glasses type

Besides glasses type there is also a technology called non-glasses type. There aremainly two kinds of this technology as figure1-3 shows, parallax barrier type andlenticular lens type. Non-glasses type also makes use of binocular disparity, butinstead of separating images just before eyes, it separates images directly on thedisplay screen. Different prepared images for left eye and right eye will pass throughparallax barrier or lenticular lens and go into observer’s left eye and right eye
respectively. And then the different images will stimulate binocular disparity andcreate stereopsis.
12

Parallax barrier typeLenticular lens typeFig.1-3:

Principle of non-glasses type 3D display system[Source:http://convert-to-3d.com/blog/3d_without_glasses_the_future_of_3d_technol
ogy.html]

Depth-sampling and multiplexing type integrates multiple layers with different depthby special mechanical structure to create 3D. Here we introduce two kinds of
depth-sampling and multiplexing types. Figure1-4 shows the light source rotation type.
13

Rotating light source arrays will stimulates the retention of vision and then creates 3D.
Figure1-5 shows the volumetric type. Volumetric displays create 3D imagery via theemission, scattering, or relaying of illumination from well-defined regions in real
space.

Fig.1-4:

Principle of light source rotation type 3D display system[Source: Takada, 2007]

Fig.1-5:

Principle of volumetric type 3D display system

14[Source: http://www.aist.go.jp/aist_e/latest_research/2006/20060210/20060210.html]

1.1.1.3 Holography

Holography is said to be the ultimate method of 3D. It first records the interference
patterns of incident light and reference light. And then play the interference patterns tocreate 3D. However, it seems like this technology still needs a long time to be applied.

Fig.1-6:

Principle of holography type 3D display system[Takada, 2007]

1.1.2 Problems of current 3D display system

We already have a lot of 3D display systems until now, but why 3D display is still not
being widely popularized? That is because they also have a lot of problems. For theglasses type, we need additional device – glasses, which will increase fatigue. For the
non-glasses type, the available view point is very limited. For the depth-sampling andmultiplexing type we need a complicated mechanical structure. For the holography,15

we still have a lot of technical restrictions and cost problems.

1.2 Purpose

Considering the problems of current 3D display systems above, we are looking
forward for a new 3D display system which can be easily used for a long time foranyone without additional devices. And also simple structure and reasonable cost are
being expected. In this research we will try to realize these expectations by proposing
a new layered 3D display system.
Furthermore, our ultimate goal is to change the current situation that 3D device isn’t
being popularized. We are looking forward to a future that our layered 3D display
system can take the place of TV in every home and make all the people can easily
enjoy the charm of 3D.

1.3 Structure of this thesis

In chapter one, we have given a general background of this research. We haveidentified the problems of current 3D display system. We also stated the general
purpose of this research.
In chapter two, we will introduce the proposal of our layered 3D display system. We
will introduce the concept of our research and the method to do it. Also we will makea brief comparison with existed layered 3D display systems.
16

In chapter three, we will talk about the system building. We will explain the design
including both hardware and software.
In chapter four, we will conduct the first experiment, motion parallax experiment, toexplore whether or in what way our system can change the ability to convey depth
perception through this method.
In chapter five, we will do the second experiment, Depth-fused 3D experiment, toverify the phenomenon of DFD in our system and then explore how the depth
perception will be changed by using DFD in a quantitative way.
In chapter six, we will integrate motion parallax and Depth-fused 3D and explore howthese two methods can make contributions to the 3D performance of our system
together.
In chapter seven, we will give out an example by using the two methods we haveverified in the above chapters. We will use the famous Japanese painting “Ukiyoe” asour content and collect the feedback from experimenters.
In chapter eight, we will make discussion about the insufficient part of this researchand the future issues.
Lastly in chapter nine, we will recap the results of this research once again and makea conclusion of this research.

17

2 Proposal
2.1 Concept of this research

We got an inspiration for 3D display research from a brand-new technology which iscalled transparent LCD. Transparent LCD is a new type LCD which you can not only
use it as the traditional LCD but also you can see through it. Figure2-1 shows anexample of transparent LCD. Samsung, the giant in the electronic field claimed thatthey had begun the mass production of transparent LCD in 2012. It makes the cost oftransparent LCD be decreasing. Based on the decreasing cost and exclusivetransparent function, Display Bank, a display researching organization, has publisheda market forecast of transparent LCD which shows it will be highly probable for thetransparent LCD to bring a huge market in recent years.

Fig.2-1:

Image of Transparent LCD[Source: http://fringeskill.blogspot.jp/2011/11/samsung-transparent-lcd-panels-we-see.html]
18

Fig.2-2:

Transparent LCD market forecast[Source: Display Bank, 2011]
By using the special function of this notable product, we came up with a new idea tobuild a layered 3D display system as figure2-3. We try to combine the transparent
LCD and traditional LCD. Because the front layer is transparent, it makes us able tocombine the images of front and rear and use the space which is not limited in the twolayers. We want to know whether it is possible to create comparatively better
stereoscopic effect by fusing the images of the two LCDs than the situation that wejust create 3D graphs on one traditional LCD. If compared with the current 3D display
systems, firstly this system does not need any additional equipment like glasses andowns a compact structure; secondly this is at a reasonable cost (our budget for thissystem is around 120,000 yen, on the other hand the average price for 3D TV is
19around 200,000 yen); and theoretically there supposes to be less fatigue because thedisplay system requires less convergence accommodation. So if our hypothesis isproved and this system is successfully verified and validated, it may be a new
approach to create a new 3D display system which is being expected.
Traditional LCD

Images on Traditional LCD

Images on Transparent LCD

Transparent LCD

Fig.2-3:

Schematic diagram of layered 3D display system

Moreover, how to create 3D sensation by our system will be the most significant thingthat we want to know. Here we will introduce our idea about how to create 3D effectby our system.
The most special feature of this system is that we separate the space into 3 parts by
the two LCDs as figure2-4 shows. How to make full use of the part 1, part 2 and part
3 is a critical issue. Starting from the special structure of our system, we came up with
an idea.
20

Fig.2-4:

Special structure of our layered 3D display system

Actually even for one traditional LCD, if we adopt some special methods to create thegraphics, to some extend it will also be able to achieve 3D effect. One of the special
methods is called motion parallax which is one kind of visual illusions of humanbeings (we will discuss in detail in Chapter 4). Based on this fact, we speculate that if
we adopt motion parallax in our system, each of the two LCD will have a certain
range round themselves to be able to show 3D effect as figure2-5 shows.

Fig.2-5:

Speculated effect of motion parallax in our layered 3D display system
21

However, we can find that the middle part between the transparent LCD and the
traditional LCD is not being used. So we have to think about another method to makeuse full use of this space. We came up with an interesting unencumbering pseudo-3D
display technique which is called depth-fused 3D (DFD) by [Suyama, 2004]. DFD
means that images at intermediate depth can be produced by simply controlling theluminance of two stacked 2D images [Date, 2007] (We will discuss in detail in
Chapter 5). By using DFD, we speculate that we can fill up the space between the 2
LCDs with 3D effect as figure2-6 shows.

Fig.2-6:

Speculated effect of depth-fused 3D in our layered 3D display system

Then, if we combine motion parallax and DFD, we further speculate that the range
where we can feel 3D will be like it shows in figure2-7. Compared with one
traditional LCD the range is supposed to be much wider.
In this research, we will start from the hypotheses above and try to prove them byexperiments. If all the hypotheses above are proved, it will turn out that we have22

found the valid way to create 3D by using our system. And it will also prove that ourlayered 3D display system can have a better capability to create 3D effect than one
traditional LCD.

Fig.2-7:

Speculated effect of motion parallax and depth-fused 3D in our system

2.2 Related research on layered 3D system

Until now, there have been several researches on the layer 3D display system. Most ofthem used DFD (Depth-fused 3D).
One of these researches is called half-mirror type. It was achieved by superimposing
two 2D display screens using half mirrors. The luminance of overlapping images was
the accurate addition of the luminance of two screens, so the perceived depth was
proportional to the luminance ratio of the two screens. The only additional opticalcomponent was a half mirror, so high-quality 3D images could be obtained easily.
However, the image appeared to be located at a depth farther away than the half23

mirror, and the size of the apparatus was large. [Date, 2007]

Fig.2-8:

Half-mirror type layered 3D display system[Source: Date, 2007]

Another type is called projection type. One research of this type was achieved byusing a stack of two transparent screens with front and rear projectors, as shown infigure2-9 that stack can be used to reduce the thickness of the display apparatus andthe distance of the image from the observer to smaller values than those of thehalf-mirror type [Date, 2007].

Fig.2-9:

Projection type layered 3D display system[Source: Date, 2007]24

Another simlilar research used fog screen instead of the two transparent screens, as
shown in figure2-10. However, two projectors are indispensable for this type, the sizeof the apparatus is still large.

Fig.2-10:

Immaterial DFD display using two fog screens[Source: Lee, 2009]25

3 System building
3.1 Hardware design

We chose the 22 inches transparent LCD (Samsung) and the traditional LCD (HP
2209t). Table3-1 is a simple contrast of their specifications.
Table. 3-1:

Speciafication contrast of transparent LCD and traditional LCD

Specification

Transparent LCD

Traditional LCD(Samsung)(HP 2209t)

22 inches

21.5 inches

1.3kg

6.4kg

Pixel Pitch

0.282mm

0.250mm

Display Colors

16.7M

1677M

1680*1050

1920*1080

Module Size
WeightNumbers of Pixels

Fig.3-1:

Real image of transparent LCD and traditional LCD
26

We built a frame to fix these two LCDs and also added some lighting equipment. The
transparent LCD is in the front and the traditional one is at the back. Figure 3-3, figure
3-4 and figure 3-5 show the front view, top view and side view of this system.

Fig.3-3:

Front view of our system

27

Fig.3-2:

Top view of our system

Fig.3-4:

Side view of our system

Because of the polarization, actually we cannot see the back LCD through the front
transparent LCD. So in order to solve this problem, we added a kind of plastic
material to break the polarization and make it possible to see through the front LCD to
the back LCD. Figure3-5 shows the polarization phenomenon.

Fig.3-5:

Polarization phenomenon28

In addition, in order to measure perceived depth in the following experiments. We
also made a measurement board as figure3-6 shows. The measurement card can besmoothly moved to front or back in the track that we set on the board.

Fig.3-6:

Measurement board

3.2 Software design

In order to explore 3D effect in our system, we need to set up a software environment
which allows us to create 3D graphics. We chose the OpenGL (Open Graphics Library)which is a cross-language, multi-platform application programming interface (API)for rendering 2D and 3D vector graphics. [Segal, 2010] However, because we have
two LCDs in this system, besides the programming platform, there are some other29

problems that we have to consider.
We have to make sure that from the front view no matter the situation we only watch
at one traditional LCD or the situation we watch trough the transparent LCD to the
traditional LCD in our system, the pattern, the size, the location and the movement of
the images should be completely the same.
To make sure this, the first problem we have to solve is the desynchronization. When
we display on two LCDs, we actually input the signals by two channels. If we use twodifferent PCs to offer the input signals, because of the different specifications thedesynchronization seems to be hardly avoided. We made it possible to output two
viewports from one application using one PC, which eliminated the problem ofdesynchronization.
Another significant problem is that we have to keep the location and size unchanged(when seen from the front). By using the function called glFrustum() in OpenGL,
which produces a perspective projection, we made it possible to draw objects which
are with the real world coordinates in our system. Simply speaking, by using
glFrustum(), we can simulate the movement of an object of real size and at real
location. The size we see on the LCD will be totally the same as the objects in realworld coordinates.
To set the function of glFrustum (fleft, fright, fbottom, ftop, zNear, zFar), we need to30

know several parameters. Figure3-7 shows the parameters that we have to set.

Traditional LCD

Transparent LCD

Fig.3-7:

Parameters to set glFrustum

However, we cannot directly measure these parameters. We have to calculate themthrough some equations as follows.
zNear = eye_z - near_z;(3-1)

zFar = eye_z - far_z;(3-2)

fleft = -( disp_width / 2.0f + eye_x - disp_x) * zNear / eye_z - disp_z;(3-3)

fright = (disp_width / 2.0f - eye_x - disp_x) * zNnear / eye_z - disp_z;(3-4)

fbottom = -( disp_height / 2.0f + eye_y - disp_y) * zNear / eye_z - disp_z; (3-5)
ftop = (disp_height / 2.0f - eye_y - disp_y) * zNnear / eye_z - disp_z;(3-6)

Here are the explanations of the parameters which we can directly measure:// eye position: (eye_x, eye_y, eye_z)31

// center of the display: (disp_x, disp_y, disp_z)// real size of the display(viewport): disp_width, disp_height// z value of transparent LCD: near_z// z value of traditional LCD: far_z
What we have to do to set the function glFrustum() is just to measure the parameters
above and fill the configuration table below. Here we give an example of ourconfiguration table.
// ==================================================// configuration// -------------------------------------------------#define WINDOW_WIDTH 3350
#define WINDOW_HEIGHT 1010// eye position in global coordinate system (cm)#define EYE_X 0.0f
#define EYE_Y 0.0f
#define EYE_Z 212.0f// -------------------------------------------------// display 1: normal LCD// -------------------------------------------------#define VIEWPORT1_X_PIXEL 0#define VIEWPORT1_Y_PIXEL 0#define VIEWPORT1_WIDTH_PIXEL 1665
#define VIEWPORT1_HEIGHT_PIXEL 1100// real size of display1 (cm)32

#define DISPLAY1_WIDTH 47.0f#define DISPLAY1_HEIGHT 26.2f// display1 center position in global coordinate system (cm)#define DISPLAY1_X 0.0f
#define DISPLAY1_Y 0.0f
#define DISPLAY1_Z 0.0f
#define DISPLAY1_NEAR_Z (DISPLAY1_Z + DEFAULT_FRUSTUM_NEAR_Z)#define DISPLAY1_FAR_Z (DISPLAY1_Z + DEFAULT_FRUSTUM_FAR_Z)// -------------------------------------------------// display 2: transparent LCD// -------------------------------------------------#define VIEWPORT2_X_PIXEL 1675
#define VIEWPORT2_Y_PIXEL 0#define VIEWPORT2_WIDTH_PIXEL 1675
#define VIEWPORT2_HEIGHT_PIXEL 1100// real size of display2 (cm)#define DISPLAY2_WIDTH 47.2f#define DISPLAY2_HEIGHT 29.5f// display2 center position in global coordinate system (cm)#define DISPLAY2_X 0.0f
#define DISPLAY2_Y -0.4f#define DISPLAY2_Z 6.0f
#define DISPLAY2_NEAR_Z (DISPLAY2_Z + DEFAULT_FRUSTUM_NEAR_Z)#define DISPLAY2_FAR_Z (DISPLAY2_Z + DEFAULT_FRUSTUM_FAR_Z)
Until now, we have successfully set up a software environment which allows us tocreate 3D graphics in our system.

33

4 Motion parallax (MP) experiment
4.1 Experimental purpose (MP)By using motion parallax which is one of the methods to create 3D sensation, we try
to measure and compare the depth perceptions in the situation of one LCD and thesituation of two LCDs to explore that comparing with one traditional LCD, whether orin what way our system can change the ability to convey depth perception. In
additional to that, we also want to explore that which is the best interval for thetransparent LCD and traditional LCD.

4.2 Experimental principle (MP)Motion Parallax means as the viewpoint moves side to side, the objects in the distanceappear to move slower than the objects close to our eyes [Yokozawa, 2010]. Becauseof the relativity, inversely if our viewpoint keeps static and we make the objects
which have different distances from our eyes move at the same speed, we can still feelthe objects in the distance appear to move slower than the objects close to our eyes.
As a result, by using the principle of motion parallax, actually even one simple
traditional LCD can also convey a certain depth perception. For example, in Figure
4-1 we simulate the motion parallax. Figure4-1 (a) shows the side view. We draw
several rows of objects with different Z coordinates and give them the same moving
34

speed to the same direction (By using OpenGL, we can simulate the movement ofobjects which has different distances from our eyes even on the flat LCD). Figure4-1(b) shows the front view. At this moment, what our brain feels is actually that theobjects which are near to us (smaller Z coordinate) moves faster than the ones which
are far from us (bigger Z coordinate). Then our brain will have a depth perception of
the objects. We may have an optical illusion that some of the objects are flying out
from the flat LCD and some are at the back of the LCD. This is why even a flat LCD
can also convey depth perception to a certain extent.

(a)

(b)
Fig.4-1:

Principle of motion parallax
35

So, what about our system? Compared with one traditional LCD, can our system havebetter performance? We will introduce the details of experiment in the following
section.

4.3 Experimental procedure (MP)4.3.1 Preparation (MP)Fig.4-2:

Schematic of motion parallax experiment

Figure4-2 shows the schematic of our experiment. In situation 1 we display someblack rectangles only on the rear traditional LCD. Each line of these rectangles has
different Z coordinate. In the situation 2, we separate the original rectangles into twogroups. We display one group with smaller z coordinates (back 3 layers) on the36

traditional LCD and another group with bigger coordinates (front 3 layers) on thetransparent LCD. For both situation 1 and situation 2, we make all the rectangles do
the horizontal moving at the same speed.
Because we also want to explore that which is the best interval for the transparent
LCD and traditional LCD, in situation 2 we tried 3 different intervals of the two LCDs.
They are 4cm, 8cm and 12cm. So totally we tested 4 kinds of intervals, 0cm (onetraditional LCD), 4cm, 8cm and 12cm. In order to decrease the absolute errors, weprepared 3 patterns of images for each situation. That is to say every experimenter
totally has to observe for 12 times. Most parameters of the patterns are the same
except for the sequence that the objects are randomly arranged in the Y axis. The
same parameters are as follows.

Table. 4-1:

Parameters of the objects we prepared to display

Size of
Rectangles

X
Interval

Y
Interval

Z
Interval

Numberof Rows

MovingSpeed

Movingdistance

2.5cm*2.5cm

3cm

3.5cm

4cm

6

0.8 cm/sec

13.5cm37

4.3.2 Execution (MP)Fig.4-3:

Scene of motion parallax experiment

Figure4-3 shows the scene of motion parallax experiment. The experimenter sat on
the chair in a certain position and put his jaw on the edge of the top part of a tripod
which is also fixed in a certain position (2m from the front LCD). Ask him to watch at
our system. Then show him the card we prepared and tell him there will be a lot ofrectangles which has the same size of this card moving in our system.
Alternately we changed the intervals of two LCDs with the movable track, display thewhole images just on the traditional LCD and then separated images on bothtraditional LCD and transparent LCD correspondently. At the same time, we used themeasurement board that we mentioned in section 3.1 to measure experimenters’ depth
perception. The measurement card can be smoothly moved to front or back in the
track that we set on the board. We moved the card in the first row to different

38positions in the Z direction. Ask the experimenter at which point he can feel the cardis at the same depth with the first row of our rectangles. When the position was
decided we retain our card in that position. Then pick up another card and move to thenext row below. Finally we recorded the positions of 6 cards.

4.4 Experimental result (MP)

Totally we had 10 people do the experiment. And in every situation, for each person
we tested 3 patterns of images (changing the sequence in the depth direction).
Table. 4-2:cm

Average results of 10 people for the MP experimentTransparent LCD
Layer1 Layer2 Layer3
Setting
10.00
6.00
2.00
0cm （1LCD） 0.60
-0.06
-1.04
4cm（2LCD）
3.38
2.85
1.76
8cm（2LCD）
6.33
5.46
4.77
12cm（2LCD） 10.59
10.08
9.37

Traditional LCD
Layer4 Layer5 Layer6
-2.00
-6.00
-10.00
-1.87
-2.08
-2.69
-2.65
-3.12
-3.38
-2.49
-3.15
-3.60
-1.94
-2.78
-3.34

Table4-2 shows the average results of the 10 people. In this table, the row of Settingmeans the depth of the objects we set in the program. The row of 0cm（1LCD）means
the perceived depth of the objects in the situation of only one traditional LCD. The
row of 4cm（2LCDs）means the perceived depth of the objects in the situation of two
LCDs with an interval of 4cm. The row of 8cm（2LCDs）means the perceived depth ofthe objects in the situation of two LCDs with an interval of 8cm. The row of 12cm
（2LCDs）means the perceived depth of the objects in the situation of two LCDs with39

Variance of data for0cm(1LCD)
6
5
4
3

2
1
-12.00-7.00

Fig.4-4:

-2.00

3.00

8.00

13.00

Variance of data for 0cm (1LCD)

Variance of data for
4cm(2LCDs)
6

5
4
3
2

1
-12.00-7.00

Fig.4-5:

-2.00

3.00

8.00

13.00

Variance of data for 4cm (2LCD)

Variance of data for
8cm(2LCDs)
6
5

4
3
2

1
-12.00-7.00

Fig.4-6:

-2.00

3.00

8.00

13.00

Variance of data for 8cm (2LCD)
40

Variance of data for
12cm(2LCDs)
6
5
4
3
2
1
-12.00-7.00

Fig.4-7:

-2.00

3.00

8.00

13.00

Variance of data for 12cm (2LCD)

an interval of 12cm. Figure4-4, 4-5, 4-6 and 4-7 show the variance for each situation.
Since this experiment is based on the perception of different people, we can find fromfigure4-4, 4-5, 4-6 and 4-7 that the variance is not so stable. As a result, before we
start the further analysis of these data, we should first make sure the significance levelof our data. We held analysis of variance (ANOVA) test for everyone’s data and got
the result which is showed in table4-3. In table4-3 , it shows that for every
experimenter, the significance level (Sig) is under 0.05. It is indicated that there isstatistical significance in the 4 groups of data for 0cm（1LCD）, 4cm（2LCDs）, 8cm（2LCDs）, 12cm（2LCDs）, which proves that in our system different interval has
different influence on the experimenters’ perceived depth.

41

Table. 4-3:

ANOVA for the data of MP experiment

Experimenter
No.

SourceType III Sum
of Squares

df

Mean
SquareF

Sig.

1

LayerDepth * Interval

303.00415

20.20015.874 .000

2

LayerDepth * Interval

341.33915

22.75613.845 .000

3

LayerDepth * Interval

376.99215

25.13366.187 .000

4LayerDepth * Interval

215.93315

14.39615.985 .000

5LayerDepth * Interval

401.04315

26.73634.504 .000

6

LayerDepth * Interval

308.63415

20.57627.048 .000

7

LayerDepth * Interval

287.19315

19.14615.134 .000

8

LayerDepth * Interval

166.43215

11.09511.032 .000

9LayerDepth * Interval

208.94315

13.93016.632 .000

10LayerDepth * Interval

267.75215

17.85013.879 .000

After finishing the initial analysis for the statistical significance of our data, here wewill explore how these data are connected to the capability of our system to create 3D
effect. To have a further analysis for the data, we made several figures which show thecontrast of setting depth and experimenters’ perceived depth in more intuitional way.
Here is the explanation of the parameters in figure4-8, 4-9, 4-10 and 4-11.
Middle barrier: the position of traditional LCD, which is also the Z coordinate of 0.
Target : the target depth we set in the program.
1LCD: average perceived depth in the situation of one traditional LCD.
2LCD 4cm: average perceived depth for 2 LCDs with an interval of 4cm.
2LCD 8cm: average perceived depth for 2 LCDs with an interval of 8cm.
2LCD 12cm: average perceived depth for 2 LCDs with an interval of 12cm.
42

Fig.4-8:

Contrast of setting depth and experimenters’ perceived depth (0cm, 1LCD)

4cm (2LCDs)
Traditional LCD

Transparent LCD

-3.38
-10
-3.12
-6
-2.65
-2
2LCD 4cm

1.76
2

Target

2.85

6
3.38
10
-15

Fig.4-9:

-10

-5

0

5

10

15

20

Z

Contrast of setting depth and experimenters’ perceived depth (4cm, 2LCD)
43

8cm (2LCDs)
Transparent LCD

Traditional LCD
-3.60

-10

-6

-3.15

-2.49
-2

2LCD 8cm
4.77

2

Target

5.46
6

6.33
-15

-10

-5

0

5

10
10

15

Z

20

Fig.4-10: Contrast of setting depth and experimenters’ perceived depth (8cm, 2LCD)

12cm (2LCDs)
Traditional LCD

Transparent LCD

-3.34
-10
-2.78
-6
-1.94
-2
2LCD 12cm
9.37

Target

2

10.08
6
10.59
10

-15

-10

-5

0

5

10

15

20

Z

Fig.4-11: Contrast of setting depth and experimenters’ perceived depth (12cm, 2LCD)
44

Figure4-8 shows the situation of only traditional LCD. Through figure4-8, we canfind that compared with the setting range of depth, the range of depth that theexperimenter perceived is much more narrow. It indicates that even though one LCD
can convey a certain depth perception, but it is limited. Another interesting
phenomenon we find from figure4-8 is that there are 5 layers which we feel themgoing backward the trditional LCD. And among these 5 layers, there are actually 2layers which we set should be in front of the traditional LCD. It seems like instead offeeling the object flying out from the LCD, the feeling of moving backward is muchstronger.
Figure4-9, 4-10, 4-11 show the situation of two LCDs. We can find that in thesituations of two LCDs, objects are perceived to be in some new positions which are
not perceived in the situation of one LCD. And if you pay attention to the front 3
layers, you will find in these situations they are all perceived to be in front of the
traditional LCD. It means by using two LCDs, we can make the objects which wethought should be at the back of the traditional LCD in situation of one LCD to fly out
to new positions. However, if we compare the front 3 layers in figure4-9, figure4-10
figure4-11 with the transparent LCD correspondingly. We can figure out that in the 3situations of two LCDs, all the front 3 layers are perceived backward to thetransparent LCD. It seems like even for the transparent LCD, the feeling of moving
45

backward is also much stronger.
Another important point is that if we compare the ranges of the depth we perceived in
the situations of two LCDs, you can apparently find the ranges in the situation of two
LCDs are much bigger than situation of one LCD. This indicates that the perceived
range of depth was expanded by two LCDs. It can be a significant support for that oursystem can enhance the capability of conveying depth perception comparing with one
traditional LCD.

Fig.4-12:

Contrast of the 4 situations in MP experiment

Figure4-12 shows the contrast of the 4 situations, and the correlation coefficients ofperceived depth and setting depth in the 3 situations of two LCDs. The correlation
coefficients are gradually increasing according to the sequence of 12cm（2LCD）, 8cm
46

（2LCD）, 4cm（2LCD）. Condsidering the experimental error, we may say that
4cm~8cm could be a better inteval for the 2 LCDs because that they have higher
correlation coefficients with the setting depth.
In conclusion, through motion parallax experiment, we find that each of the two LCD
have a certain range around themselves to be able to show 3D effect. Because of thiseffect, our system expanded the range of depth we perceived, which further supports
the hypothesis that our system can enhance the capability of conveying depth
perception comparing with one traditional LCD. Moreover, the data indicates that thebest interval of the two LCDs should be between 4cm and 6cm.
Nevertheless, the results also reflect a problem. If you pay attention to the depth weperceived for Layer 3 and Layer 4 (middle two layers), you will find there is actuallya gap between the two layers which makes the images be not continuous. To solve thisproblem, we will introduce another method to create 3D sensation in the following
chapter.

47

5 Depth-Fused 3D (DFD) experiment
5.1 Experimental purpose (DFD)

By using DFD (Depth-fused 3D) which is another method to create 3D sensation, we
try to solve the problem that there is a discontinuous representation gap between the
two LCDs in the last experiment using motion parallax. In this experiment, we willverify the phenomenon of DFD in our system and then explore how the depth
perception will be changed by using DFD in a quantitative way.

5.2 Experimental principle (DFD)The DFD effect was originally found during a study on interpolating the layers of
discrete 2D images. Images at intermediate depth can be produced by simply
controlling the luminance of two stacked 2D image [Date, 2007]. DFD perception
occurs when two 2D images are displayed such that they are superimposed on two
transparent screens with varying luminance and the observer perceives a 3D image.
[Lee, 2009]
Figure5-1 explains the fundamental of DFD. In figure5-1 a, in the depth direction as
viewed from the observer, there are two 2-D images being displayed on two
transparent planes. The two 2-D images are at the same height with our eyes. What48

the observer supposes to perceive is actually not 2 separated 2-D images but one fused
3D image in the depth direction. In figure5-1 b, it shows that we can perceive acontinuous depth change of the depth-fuse 3D image when the luminance ratio
between the two 2-D images at each point is continuously changed according to the
distance ratio between the object and the two image planes [Takada, 2006]. The
image appears closer to the observer if the front screen is more luminous and farther
away if the back screen is more luminous.

Fig.5-1:

Principle of DFD[Source: Takada, 2006]49

5.3 Experimental procedure (DFD)
5.3.1 Preparation (DFD)

Fig.5-2:

Schematic of DFD experiment

Figure5-2 shows the schematic of this DFD experiment. Firstly based on the result
from last chapter, we found that the best interval for the 2 LCDs is between 4~8cm.
Here we make the interval be 6cm. As Figure shows, we display several lines ofsquares with different luminance to each LCD. We keep the front and the rear lines ofsquares being with different luminance. For example we set the front line of squares’
luminance to be 80% and set the rear line of squares’ luminance to be 20%. Then weoverlap the two lines of squares and create the DFD effect. In order to explore how
the depth perception will be changed by using DFD in a quantitative way, we tried totest as many combinations of luminance as possible. We designed several

50

combinations of luminance for the 2 LCDs as Table5-1 shows.
Table. 5-1:
LCD

Combinations of luminance for DFD experiment
Luminance Proportion

Front (Transparent) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.3 0.7
Rear (Traditional)

1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.3 0.7

Both of the two LCDs cover the luminance of 0%~100% at an interval of 10%. And
the luminance percentages of the two LCDs are complementary which means the sumof them is 100%. In addition to that, we also want to know what will happen if thesum of luminance percentages is not 100%. So we added the combinations of 0.3/0.3
and 0.7/0.7. We will compare the result of 0.3/0.3, 0.5/0.5 and 0.7/0.7.
However, before we start the DFD experiment, there is still one problem that we haveto solve. Because of the different specifications of the two LCDs and the film that wecovered on the traditional LCD to eliminate the polarization, actually the color
performance of the two LCDs is different. For example, even if we set the same blackcolor (RGB: 0, 0, 0), the front transparent LCD may still look like different color withthe rear traditional one. As a result, it is inevitable to make color compensation tokeep them have the same standard for color performance. We made a color
compensation table as table5-2 shows. Figure5-3 shows the final effect of color
compensation, the upper line of squares are displayed on the rear traditional LCD and51

lower line of squares are displayed on the front transparent one. The color
performance is approximately equal to each other.
Table. 5-2:

Fig.5-3:

Color compensation table

Final effect of color compensation
52

5.3.2 Execution (DFD)

Figure5-4 shows the scene of DFD experiment. The experimenter sat on the chair in acertain position and put his jaw on the edge of the top part of a tripod which is also
fixed in a certain position (2m from the front LCD). Ask him to watch at our system.
Then show him the card we prepared and tell him there will be a lot of rectangles
which has the same size of this card. But this time they will not move.

Fig.5-4:

Scene of DFD experiment

We displayed lines of squares with different combinations of luminance tocorresponding LCD. We used the same measurement board that we mentioned in
section 3.1 to measure the experimenters’ depth perception. And the following
experimental procedures were the same as mentioned in the Section 4.3.2.

53

5.4

Experimental result (DFD)

Totally we had 10 people do the experiment. And for each person we tested 3 patternsof images (changing the sequence in the depth direction). Figure5-5 shows theaverageresults and the standard deviation of the 10 people. X axis represents the

combinations of luminance of rear and front LCD.Y axis represents the perceived
depth (Z coordinate).

Fig.5-5:

Average result and variance of 10 people for the DFD experimentFirstly we should make sure that whether different combinations of luminance will
result in different perceived depth or not. So we held the analysis of variance(ANOVA) test to check the significance level of our data. In table5-3, it shows thatthe significance level (Sig) is under 0.05. It is indicated that there is statistical54

significance in different combinations of luminance, which proves that combinationsof luminance has different influence on the experimenters’ perceived depth.
Table. 5-3:
Sum ofSquares

ANOVA for the data of DFD experimentdf

Mean
SquareBetweenGroups326.69810

32.670WithinGroups62.242

99

.629

Total

388.940

109

F

Sig.

51.963.000

To have a better analysis for the data. We made figure5-6 which shows the data in amore intuitional way. We also draw a regression curve () based on the data.
y = 0.0153x3 - 0.2883x2 + 2.0687x - 1.9372

Fig.5-6:(5-1)

Regression curve of the data for the DFD experiment55

Focusing on the regression curve which indicates the trend of perceived depth, we canfind that as the combinations of luminance changes the perceived depth also changes.
The image appears closer to the observer if the front LCD is more luminous andfarther away if the back LCD is more luminous. For example, the result for
combination of 0.2/0/8 is around 2.0cm (away from the traditional LCD), on the otherside, the result for combination of 0.8/0/2 is around 4.5cm (away from the traditional
LCD), which appears closer to the observer. And the curve continuously crosses thewhole interval between the two LCDs, making the discontinuous part be filled up. We
have successfully verified the DFD phenomenon by our layer 3D display system. We
also tested the situation that the sum of luminance percentages is not 100%. Figure5-7
is the result of this situation. We can see the results for the three kinds of

Fig.5-7:

Result of the situation that the sum of luminance percentages is not 100%.
56

combinations are all around 3cm (away from the traditional LCD). We also analyzed
the statistical significance of the data for three combinations. Table5-4 shows that thesignificance level (Sig) is above 0.05 which means there is no statistical significanceamong the three kinds of combinations. From the data we can say that if the
proportion of luminance is the same, no matter the sum of the luminance percentages
is 100% or not, there will be same effect on the perceived depth.

Table. 5-4:

ANOVA the situation (sum of luminance percentages is not 100%)
Sum ofSquaresdf

Mean
SquareF

Sig.

BetweenGroups

.824

2

.412

.621

.540

WithinGroups

57.720

87

.663

Total

58.54489

In conclusion, through DFD experiment, we successfully verified the DFD
phenomenon in our system and found that we can smoothly fill up the discontinuousinterval between the two LCDs which had been a problem in the last motion parallax
experiment. We also deduced one regression curve to be a reference for how we canrealize a certain depth perception by using DFD in a quantitative way. For the
problem that whether the sum of luminance percentages is 100% will have different
57

influence on perceived depth, our data shows that there is no significant difference..
Until now we have finished the motion parallax and DFD experiment respectively. We
have found the way to create 3D effect around the two LCDs and between them. Whateffect will we get if we combine these two methods together? We will introduce thatin the following chapter.

58

6 Motion parallax and Depth-fused 3D experiment
6.1 Experimental purpose (MP+DFD)

By combining motion parallax and DFD, we try to fuse the range (around the two
LCDs) where can represent the 3D effect by using motion parallax and the range(between the two LCDs) where can represent the 3D effect by using DFD. We want toverify that whether the two methods of creating 3D can integrate the space outside thetwo LCDs and between them, and make it possible to convey 3D sensation.

6.2 Experimental procedure (MP+DFD)
6.2.1 Preparation (MP+DFD)

Figure6-1 shows the schematic of this combination experiment. We still keep theinterval of the two LCDs be 6 cm. Here we have 6 lines of squares with 6 different z
coordinates of -2, 0, 2, 4, 6 and 8. The traditional LCD is at the position of z=0 andthe transparent LCD is at the position of z=6. For the middle two lines of squares
which are in the yellow frame, we applied DFD. And we made all the 6 lines ofsquares in the green frame do the same horizontal moving like we did in the motion
parallax experiment, which means we applied motion parallax to all of them.
Figure6-2 gives an example of the images displayed on the two LCDs for thisexperiment. As you can see that the upper two lines are being displayed only on the59rear LCD, the lower two lines are being displayed only on the front LCD, and the
middle two lines are being displayed on both of the two LCDs with different
luminance.

Fig.6-1:

Fig.6-2:

Schematic of MP+DFD experimentImage of MP+DFD experiment60

In addition, because we want to apply DFD, we have to think about the color. For theupper two lines and the lower two lines, we made them be black based on the color
compensation table5-2 in Chapter 5. For the middle two lines, we have to decide theluminance combinations to make them approach to the positions of Z=2 and Z=4.
From the regression curve which indicates the trend of perceived depth in Figure, we
found that the luminance combinations for the positions of Z=2 and Z=4 should be
0.2/0.8 and 0.7/0.3 (rear/ front).

6.2.2 Execution (MP+DFD)

On the whole, we used the same measurement method as we did in the Chapter 4 and5. We measured all the 6 lines of squares’ perceived depth.

6.3 Experimental result (MP+DFD)

Totally we had 10 people do the experiment. And for each person we tested 3 patternsof images (changing the sequence in the depth direction). Figure6-3 shows theaverage result and figure6-4 shows the variance of the data. Figure6-3 is also the sideview of our system, the horizontal axis shows the perceived depth of the lines and thelongitudinal axis shows the vertical position of the lines. The red bar is the target
depth we set in the program and the blue bar is the real perceived depth by theexperimenters.
61

From figure6-3, we can see that from the left to the right, the values of the blue bars
tend to be continuously and smoothly increasing. And the perceived depth cover theFig.6-3:

Average result of 10 people for the MP+DFD experimentarea from z=-0.92 to z=7.72. It indicates that we successfully integrated the spaceoutside the two LCDs and between them. For some lines of squares, theexperimenters had a feeling of flying out from our system. For some lines of squares,62the experimenters had a feeling of moving to the back side of our system. For somelines of squares, the experimenters had a feeling of existing between our two LCDs.
We have made both the range around our two LCDs and the range between them able
to convey the depth perception simultaneously.

Fig.6-4:

Variance of the data for the MP+DFD experimentThrough this motion parallax and Depth-fused 3D experiment, we know that it ispossible to make the depth perception more smooth and continuous by combing thetwo methods of creating 3D effect in our system.

63

7 Application example
Through the three experiments in chapter 4, chapter 5 and chapter 6, we have foundthat the combination of motion parallax and Depth-fused 3D is a valid way to create
3D effect in our layer 3D display system. In this chapter, we will introduce one
application example and discuss about the feedback from people who have watchedthat.
We used one of the famous Japanese traditional paintings called Ukiyoe as ourapplication example. Figure7-1 shows the schematic diagram of how we displayed
Ukiyoe in our layered 3D display system. Firstly, as shown in Figure7-1, we separated
Ukiyoe into five layers of pictures based on the depth of different objects. We
displayed the first three layered onto the front transparent LCD and the last threelayered onto the rear traditional LCD as shown in figure7-2. Then we simulated the
movement of our eyes to make the five layered do horizontal moving, which means
conducting motion parallax. For the middle layer (No. 3), because it is displayed bothon the two LCDs and with the same luminance, based on the result of DFD
experiment, it should be perceived just in the middle of the two LCDs. Combinedwith the effect of motion parallax, the five layers of pictures will finally be presented
in a stereoscopic way as shown in figure7-2. As a comparison, we also displayed all64the five layers on the traditional LCD and simulated the same eye movement as
figure7-3 shows.

1

2

Fig.7-1:

3

Separation of Ukiyoe

5

4

65

Fig.7-2:

Schematic diagram of displaying 3D Ukiyoe in 2 LCDs
66

Fig.7-3:

Schematic diagram of displaying 3D Ukiyoe in 1 LCD
67

2 LCDs

1 LCD

Fig.7-4:

Real pictures of Ukiyoe in two situations

It is hard to tell the difference between these two situations by the 2D pictures. Let’s
pay attention to the feedbacks from 10 experimenters. We made a questionnaire as
follows. Here we will show the results from 10 experimenters with the questionnaire
together.
68Questionnaire
You will see two short videos, please pay attention to the sense of depth andanswer Q1~Q4 by comparing the two videos. (Video1: 1 LCD, Video2: 2 LCDs)
Question 1
If the range of depth perception in the Video1 is 10, how much do you think it should
be in Video2? (Examples: 2 times—20, half―5)
Answer 1:

Question １
30
25
20
2LCDs

15

1LCD

10
5
0

Fig.7-5:

Result of Q1

Question 2
Between the object that you think farthest away from you and the object that you
think nearest to you, how long do you think the distance should be? Please choose theclosest answer for each video.
2cm, 4cm, 6cm, 8cm, 10cm, 12cm, 14cm, 16cm, 18cm, 20cm, 22cm, 24cm, above69

Answer 2:

Question 2

Cm
20
18
16
14
12
10
8
6
4
2
0

2LCDs
1LCD

Fig.7-6:

Result of Q2

Question 3
How many layers in the depth direction do you think there are? Please choose theclosest answer for each video.
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, Above
Answer 3:

Question 3
8
7
6
5

2LCDs

4

1LCD

3
2
1
0

Fig.7-7:

Result of Q3
70Question 4
How do you think the 3D sensation of the two videos? Example: if strong, pleasechoose 5.
5. Strong

4.

Slightly strong

3.

Normal 2.

Not very 1.

Not at all

Answer 4:

Question 4
65 Strong
4 Slightly strong

2LCDs

3 Normal

1LCD

2 Not very
1 Not at all0

Fig.7-8:

Result of Q4

Result of Q1 and Q2 shows that the range of depth perception of our layered 3D display
system is over 2 times larger than the situation of one LCD. And from result of Q2,
we can also find that the average distance between the perceived farthest object andthe perceived nearest object is around 14cm, which is much bigger than 6cm (theinterval of the two LCDs). This result is identical with what we proved in the previous
chapters. Comparing with one traditional LCD, our system has apparently enhanced
71the capability of conveying depth perception. Furthermore, from result of Q3, we canfind another interesting thing. In the situation of two LCDs, averagely theexperimenters can figure out more than 5 layers. However in the situation of one LCD,
they can only figure out less than 3 layers. This result indicates that our system evenincreased the resolution of depth perception. And lastly, result of Q4 shows thedifference of overall 3D sensation in the two situations. Most of the experimenter
thinks that our system has a comparatively strong 3D sensation. On the other hand,most of them think that one LCD’s 3D sensation is just normal.
Through this Ukiyoe example, the experimenters admitted the 3D performance of ourlayered 3D display system.

72

8 Discussion
In this chapter, we will discuss the future issues and future prospects of our system.
Until now in all the experiments that we have conducted, we simulated the eye
movement when adding motion parallax. In that situation, our viewpoint was fixed.
However in fact, it is possible to realize free viewpoint in our system. Figure8-1
introduces one possible way by using Kinect. Kinect is a device developed byMicrosoft, which can detect the motion of humans by collecting the depth information.
By using Kinect, we can trace the movement of our eyes and make the contents in our

Fig.8-1:

An idea to realize free viewpoint for our system in the future73

system able to change as our viewpoint changes. If this idea is realized in the future,
our system will become a more free style 3D system.

Another issue is about the color. As we know that the transparent LCD is still not amature product yet. There are some still problems or technical restrictions. One of the
problems we care about is the color performance. As you can see in figure7-4, eventhough we present better 3D effect by using our system, the color performance is not
so perfect. Because the transparent LCD only has 16.7M display colors, inevitably
there will be influence on restoring the color. Nevertheless, we believe that as thetechnology of transparent LCD develops there will be much high quality transparent
LCD coming soon in the future. The problem of color distortion will be solved.
And we also believe that the transparent rate will be also increased in the future. If wehave better transparent rate, we can even expand our system to be like figure 8-2. We
can add the number of transparent LCDs and make the depth perception more
excellent.

Fig.8-2:

Image of an advanced layered 3D display system74

9 Conclusion
In this research, concerning the problems of current 3D display system, we proposedand successfully built a new layered 3D display system by combining the transparent
LCD and the traditional LCD. Based on the special structure of our system, we put
forward two methods (motion parallax and DFD) to realize 3D effect. We made theexperiments to prove the feasibility of the two methods in our system and theapplication example to evaluate the 3D performance of our system.
Through a large number of experiments, we have obtained several significant
conclusions. Firstly, the combination of motion parallax and DFD is a valid method tocreate 3D effect in our system. Secondly, through the combination of motion parallax
and DFD, we successfully expanded the range of depth perception and increased theresolution of depth perception comparing with the situation of one traditional LCD.
And finally, from the feedback from experimenters, the overall 3D performance of oursystem has been highly evaluated.
All in all, we have successfully built a simple structured layered 3D display system
which does not need any additional device at a reasonable cost. And we have proved
the 3D performance of this system.

75

Acknowledge
First of all I would like to thank Professor Ogi Tetsuto, my supervisor. He has
provided me with an incredible amount of knowledge, advices and encouragement
over my two years in Keio University. Professor Ogi guided me step by step andprovided me with countless suggestions regarding the direction and contents of myresearch. I am very grateful for his patience and understanding.
I would like to thank the former associate teacher Tateyama Yoshisuke for his
supports. He gave me great help especially in the programming part of my research. I
am very grateful for his enthusiastic attitude.
I would also like to thank associate Professor Ioki Makoto, my secondary supervisor.
Professor Ioki provided me with advices on the logic of my research. I am very
grateful for his precious advices.
I would then like to thank my fellow classmates, for their assistance, andencouragement. Especially Leo and Rob, they have helped the experiments for me forcountless times and give me incredible amount of advices.
I would also like to thank the members in Ogi laboratory and students in SDM who
tested my system, took my questionnaire, and provided useful feedbacks andsuggestions.
Finally, I want to thank my families who have kept supporting me for these two years.
76ReferenceDate, M., & Takada, H. (2007). Small-Depth-Error Display Using Depth Fused 3D(DFD). Taiwan-Japan Joint Conference on Communications Technology 2007.
Display Bank. (2011). Transparent Display Technology and Market Forecast.
Gabor, D. (1948). A new microscopic principle. Nature, Vol. 161, pp. 777-779.
Kim, H. (2010). Trend and Prospect on 3D Industry and R&D. Hyundai IT
Corporation.
Lee, C., DiVerdi, S., & Hollerer, T. (2009). Depth-Fused 3D Imagery on an
Immaterial Display. IEEE Transactions On Visualization And Computer
Graphics January/February 2009, VOL. 15, NO. 1.
Ohkoshi, T. (1980). Three-dimensional displays. Proceedings of the IEEE, Vol. 68, No.
5, pp. 548-564.
Qian, N. (1997). Binocular Disparity and the Perception of Depth. Neuron, 18,359-368.
Segal, M., & Akeley, K. (2010). The OpenGL Graphics System: A Specification. The
Khronos Group Inc.
Suyama, Y. I. (2004). Apparent 3-D Image Perceived from Luminance-Modulated
Two 2-D Images Displayed at Different Depths. Vision Research.
77

Takada, H. (2007). Research on Clarification of Depth-Fused 3-D Visual Illusion and
its Application to 3-D Display. Waeda Univeristy.
Takada, H. S. (2006). Front and Rear Image Generation Module for Depth-fused 3-D
Display. IEEE Transactions on Consumer Electronics, AUGUST 2006, Vol. 52,
No. 3.
Travis, A. (1997). The display of three-dimensional video images. Proceedings of theIEEE, vol. 85, pp. 1817-1832.
Yokozawa, K. (2010). Visual Science. Keisoshobo Co.Ltd.

78

Conference attendance
1. Di Xiong, Yoshisuke Tateyama, Tetsuro Ogi: Layered 3D Display System Basedon the Combination of Transparent LCD and Traditional LCD, Design
Engineering Workshop in Kitakyushu, 2013
2. Di Xiong, Yoshisuke Tateyama, Tetsuro Ogi: Depth Representation in Layered 3D
Display Using Transparent LCD, Tele-Immersion Technology Committee, The
Virtual Reality Society Japan, 201479

Appendix
In the discussion part, we have discussed an idea of adding Kinect to realize free
viewport in our system. After finishing the main body of this thesis, we actuallycontinued to make a progress. We made a prototype of the idea.
First using Kinect SDK, we made an application to detect the position of people’s eye(EYE_X, EYE_Y, EYE_Z). Then we send the position to our original system byusing UDP. We replace the eye position (EYE_X, EYE_Y, EYE_Z) that we
mentioned in the software design part in chapter3. As a result the movement of theobjects in our system will reflect the movement of people’s eye movement.
Here we will show the example of Ukiyoe system attaching Kinect.

Fig.A-1:

Design of eye detection application by Kinect80

Fig.A-2:

Fig.A-3:

Ukiyoe system with Kinect

Test scene of Ukiyoe system with Kinect (1)81Fig.A-3:

Test scene of Ukiyoe system with Kinect (2)Fig.A-4:

Test scene of Ukiyoe system with Kinect (3)82