Proposal for the Object Oriented Display :The Design and Implementation of the MEDIA3
Naoki KAWAKAMI, Masahiko INAMI, Taro MAEDA,and Susumu TACHI
Faculty of Engineering, University of Tokyo
7-3-1 Hongo, Bunkyo-ku Tokyo 113, JAPANkawakami@star.t.u-tokyo.ac.jp, minami@star.t.u-tokyo.ac.jp, maeda@star.t.u-tokyo.ac.jp
tachi@star.t.u-tokyo.ac.jp
Abstract1.

Screen.

This paper describes design and implementation of the3

MEDIA (MEDIA cube). In this paper we also propose

traditional flat display systems, such as CRT or2.

3

display systems which locate on operator's head,the concept of “object oriented display”. The MEDIA

such as HMD (which was developed byis trial product of an example of “object orientedFakespace Inc. in 1988).

3display”. The MEDIA

consists of liquid crystal

3.

display systems which surround operator, such as

displays (LCDs) which arranged in the shape of a cubic

OMNIMAX (which was developed by IMAX

body (exactly a rectangular parallelepiped). According

Inc. ) , CAVE[1] (which was developed in Univ.

to the position of an operator's eye and the position ofof Illinois in 1993) or CABIN [2] (which was3MEDIA , synthesized images of virtual objects locateddeveloped in Univ. of Tokyo in 1997).

inside the MEDIA3 appears on each LCD. Because themotion of the MEDIA3 and the synthesized images on

The MEDIA3 is fourth type of display systems, that is ,each LCD are interactive, it is very useful to observe orMEDIA3 is display systems which surrounds an object.

recognize 3-dimensional shape of the virtual object

In comparison with those previous three types , theinside the MEDIA3.

MEDIA3 is more conscious of the object.

Keywords : object oriented display, virtual reality,

Figure 1 shows positional relationship between thevisualization, CAVE, display system.

operator, the object and display system. HMD is thedisplay system which surrounds the operator’s head

1. Introduction

and CAVE or CABIN surrounds the operator’s body.
And CRT is located between the operator and the3

1.1 MEDIA Overview

object. In the case of object oriented display, display

Display systems for virtual reality / computer

encloses the object.

visualization can be grouped into following three types.

HMDCRTCAVE,OMNIMAXO b je ct O rien ted D isp lay

Figure 2 : MEDIA3
Figure 1: Positional Relationship between the Operator,

the Object and Display System

In other words, the purpose of the MEDIA3 is thepresentation of the virtual object, though the purposeof previous three types display systems is thepresentation of the virtual environment. The MEDIA3is duality of display systems such as OMNIMAX,CAVE or CABIN. In the case of OMNIMAX, CAVE
or CABIN, an operator is located inside the displaysystem and see outer virtual world through the display.

Figure 3 : The Structure of MEDIA3

And in the case of MEDIA3, an operator is locatedoutside the display system and see inner virtual object
Figure 4 shows the system of the MEDIA3. On the top

through the display.

face there is a transmitter coil of “POLHEMUS”

1.2 Details of MEDIA3 design
3sensor, whichmeasures 3-dimensional relative

The MEDIA consists of liquid crystal displays (LCDs)

position of receiver coil to transmitter coil by using

which arranged in the shape of a cubic body (exactly amagnetic field. And the operator put on a sensor cap,

rectangular parallelepiped 159mm(W) x 127mm(H) x

which have a receiver coil. In this way, we can obtain

189mm(D) 1.8kg(Weight)

see figure2,3). Each LCD

the relative position of MEDIA3 to operator’s viewis 84.2mm in length and 115.2mm in width and thepoint. In this system, we use a SGI IMAPCT2 for thenumber of pixel is 224,649(960 x 234). And the viewgraphic engine, and Impact Channel Option to output 4

angle is 120 degree in horizontal 50 degree in vertical.

images (NTSC) for each LCDs. But we are also able to

It is ideal that LCD is square, but considering the costbuild the system using 4 computers for each LCDs.

we use common rectangle LCD.

Operator

Head Tracking
Unit

LCD
Control Unit

GraphicLCD

EngineLCD

right + left
æ 2nearö00ç÷
right - leftright - left
ç
÷
2near
top + bottom
ç 0
÷
0
Pf =ç
÷
top - bottom top - bottomç
far + near 2 far × near÷00ç÷
far - nearfar - near
ç
÷
-101
è 0
ø

LCD
Figure 4 : Block Diagram of MEDIA3(left, top,- near)
And in this paper we describe how to synthesize thoseimages. First, track operator's head position by
POLHEMUS sensor (60 per second / maximum, 20 parsecond / average) and calculate the operator's

View point
far(0,0,0)

viewpoint. According to the obtained viewpoint data,
3-dimensional data of virtual object inside the MEDIA3near(right, top, -near)and the position of four corners of top plane LCD ofMEDIA3, perspective view for top LCD can calculate
by following way (using OpenGL).
We define the reference coordinate system as Figure 5.

Figure 6 : Perspective Projection

Then the projection matrix for front face Pfront is shown
Top face
Center ofusing a view point v(vx,vy,vz),

Y

MEDIA3Pfront = Tv × PfZO

Left facewhere Tv is -v parallel translation matrix,

X

Front face
Right face

Figure 5: MEDIA3 Reference System

As well known, The projection matrix of figure 6 is :æ1
ç0Tv = çç0çè001000 - vxö÷0 - vy÷1 - vz ÷÷0 1 øand using the width w, the height h and depth d,
replace the variable as following.

dimensinal virtual object by MEDIA3. Prepare manyì r ig h t = - 1 w - v x2
ï1
ïle ft =w - vx
ï2
ï1h - vyïï b o t t o m = 2
í
1to p =h - vyï2ïï near = - 1 d + vz
2
ï1
ï
fa r =d + vz
ïî2

photos from various angle in computer's memory, andselect suitable photo according to the operator'sviewpoint. Then mapping the photo on the plane whichis perpendicular to the line from viewpoint to thecenter of MEDIA3. This means that not only virtual /computed object but also real object is able to be
displayed by MEDIA3.

It is very easy to derive the matrices for the other face.

1.4 Applications

Notice that since some graphic library (including

For the application of MEDIA3, we suggest someOpenGL) defines the display plane as x-y plane, weexamples. MEDIA3 is very useful for museum exhibits,

need to multiply the matrix by convert axes matrix

for visualizing engineering or medical data such as

and/or multiply by the rotation matrix. Then we obtain

CAD and MRI, as well as for communication,

all projection matrices and able to synthesize alleducation and entertainment. For example we can useimages. Keeping on these sequence(60 times per

MEDIA3 for the simulation of a wind-tunnel test.

second / maximum : 20 times par second / average), we

MEDIA3 will allow us to get more intuitive andcan use MEDIA3 interactive.

multilateral knowledge than when merely seeing the3We indicate that MEDIA is duality of CAVE (orresults on a 2-D display.

CABIN). In the case of CAVE (or CABIN), anMEDIA3 can also be a useful device for showing 3-operator is located inside the display system and see

dimensional crafting and assembly processes. When

outer virtual world through the display. And in the caseusing an ordinary display, it is usually difficult to3of MEDIA , an operator is located outside the display

demonstrate how to make a 3-dimensional structuralsystem and see inner virtual object through the display.

object. But using MEDIA3, this can be done easily

So to speak, MEDIA3 is not “CAVE” but “CAGE”.

because operator can directly compare the real object

This means some techniques for CAVE (or CABIN) isand the CG model.

3It will possible and easy toAs we have already mentioned, MEDIA3 can be usedcreate common graphic library for CAVE (or CABIN)

as an electric pop-up encyclopedia or a virtual museum.

suitable for MEDIA .
3and MEDIA .

Operator can even touch and handle an object which isdangerous or rare in the real world. Of course,

We also point out that graphic engine will synthesize atadditional programming will allow for more interaction

most three images at same time. Because when we seebetween operator and the virtual objects. MEDIA3 hasa certain face, we cannot see the opposite face at same

many possibilities for educational applications.

3six face MEDIA ,And using computer network such as Internet, we canwe need graphic engine which can display at leaseshare the 3-dimensional object like documents, pictures,

three images and switching unit for selecting output

sounds or movies. For example we can use MEDIA3

display.

with WWW browser. On a certain WWW-homepage,time. Even if we want to constructthese is 3-dimensional data which described in VRML,

1.3 Using Multi-viewpoint Pictures

DXF or other 3-D data format. An operator access thisWe also suggest not only 3-dimensional data but also

page and click the object then the 3-dimensional data ismulti-viewpoint pictures is effective for showing 3-

downloaded and show the 3-dimensional object by

MEDIA3.

display. Owing to this feature, we can recognize 3dimensional object precisely. And we are able to2.

Proposal of the Concept of “Object

operate more quickly and correctly.

Oriented Display”
2.2 Conscious of the Object
2.1 Outline of the Concept of “Object Oriented

Imagine a wind-tunnel test of virtual car. There isDisplay”

virtual car model in the center of virtual wind-tunnel.

In this paper we propose the concept of “object3

And you want to observe the flow of air from various

oriented display”. The MEDIA is typical example ofangle. Of cause, it is possible by traditional VR display“object oriented display”. Using object oriented

such as HMD or CAVE. But if you want to move thedisplay, the operator can recognize a virtual object as ifvirtual car, it will be very hard, because you cannot

it is a real object, and handle the virtual object throughhandle virtual object. There is three way to solve thisthe object oriented display. We define the object

problem.

oriented display as display which satisfy following
three conditions.

(1) Using indirect device such as mouse, keyboard,and so on.

1.

2.

3.

The display has function to show the virtual(2) Using force / tactile feedback device

object.

(3) Using object oriented display

The display has function to operate the virtualobject inside the display by operating the display

The first way, you need some training to operate as you

itself.

want. Because you must learn how to convert theThe operate to the display is equivalent to themotion which you want into the operation of those

operate to the virtual object inside the display.

device. Generally speaking, indirect devices is lessuseful than direct devices.

In other word object oriented display is the display

The second way, you need some of expensive and/or

which enables an operator to perceive and to operatebinding device. Force / tactile feedback device isthe virtual object as if it is real object.

experimentally device under present circumstance.
After all, the best way is to use object oriented display.

2.1 Adopt the Human Skill

For example using MEDIA3, you can handle and

The first merit of using object oriented display is it isobserve the virtual object inside the MEDIA3 very

able to adopt human skill. That is to say, we handle oreasily.

look about the object oriented display in same way toAs described above, object oriented display enables tohandle or look about the real object. In other word,

handle caged virtual object through the display itself.

object oriented uses human skill which studied during

And we also indicate that display systems such as

one’s life. Because we repeat same action from theHMD or CAVE are conscious of the environment, andtime we born to now , when we act, we estimate

object oriented display is conscious of the object.

correctly what will happen. Especially we interlock
view space and tactile space, so we can estimate the3. Conclusion

future vision when we handle an object, and canObject oriented display is very easy and intuitively toconjecture what was happened from the vision.

operate because the operation apply the native human

So it is very easy and natural to use the object orientedskill. So very easy to learn how to operate for anypeople. Secondary merit is that visual space fits haptic
space because input device and display device aresame. One of the demerit is object oriented display is
not suitable to show virtual scene or virtualenvironment. But this in not fatal problem because
object oriented display is able to coexist with thedisplays which is effective to show virtual scene orvirtual environment such as HMD, CAVE or CABIN.

References[1] Carolina Cruz-Neira, Daniel J. Sandin, Thomas A.
DeFanti: Surround-Screen Projection-Based Virtual
Reality: The Design and Implementation of theCAVE, COMPUTER GRAPHICS Proceedings,
Annual Conference Series, 135-142,1993[2] Michitaka Hirose, Tetsuro Ogi, Shohei Ishiwata andToshio Yamada: A development of Immersive
Multiscreen Display(CABIN), Proceedings of the
Virtual Reality Society of Japan Second Annual
Conference, 137-140, 1997 (in Japanese)[3] Naoki Kawakami, Masahiko Inami, Taro Maedaand Susumu Tachi : MEDIA3 the Virtual Hologram,
Proceedings of the Virtual Reality Society of Japan
Annual Conference, 99-100, 1996 (in Japanese)[4] Masahiko Inami, Naoki Kawakami, Taro Maeda
and Susumu Tachi : Virtual Hologram Proposal for
the Object Oriented Display, Proceedings of theVirtual Reality Society of Japan Annual Conference,
139-142, 1996 (in Japanese)[5] Naoki Kawakami, Masahiko Inami, Taro Maeda
and Susumu Tachi : Study of Object OrientedDevice, Proceedings of the Virtual Reality Societyof Japan Second Annual Conference, 340-341,
1997 (in Japanese)