A TILED DISPLAY SYSTEM FOR IMMERSIVE EDUCATION
Sang-Youn Kim
Interaction Lab. Korea University of Technology and Education
307 Gajeonri, Byeongcheon-myeon, Cheonan, Chungnam, 330-708, Korea
Hyen-Keun Park, Do-Yoon Kim
Withrobot Lab. 4F Dueon Bldg, 1708-6, Seocho-Dong, Seocho-Gu, Seoul, 137-070, Korea
Keywords: Virtual Education, Virtual Reality, Virtual Training, CAVE, Tiled Display.
Abstract: Virtual reality systems may be used as a new educational tool because a user can be provided immersive
sensation as he/she experiences a real object. A tiled display is one of the virtual reality systems which
generates high-quality images and guarantees wide view angle using multiple projectors. In this work, we
present a tiled display system which has high resolution screen (its resolution is 4096 x 1536 and its
effective resolution is 3200x1200). We apply a seamless technique to this system in order to remove joint
lines and to improve the quality of images. Furthermore, we implement educational contents for
experiencing a CMOS manufacturing process based on the proposed tiled display system.
1 INTRODUCTION
Even though many education systems provide a
wide range of benefits for students, the education
systems have some problems to be solved before
accepting. One of these problems is that many
systems do not provide immersion and the sense of
reality to users. Virtual reality technology allows
users to experience the same sensation as if they
watch and feel real objects. Therefore, the education
system based on the virtual reality technology can be
a solution for immersive training because VR
systems enable users to experience phenomena in
virtual environment which are difficult to illustrate
in real world. Furthermore, users can learn how to
operate a machine or a target device in virtual world.
Virtual reality technology in its early stage has
been focused on displaying and rendering the shape
of a target object on 2D monitors or limited screens.
These systems are not suitable for the following
cases: 1) where visual contents are important; 2)
where high resolution display is necessary; and 3)
where a wide field of view is required. For these
cases, researchers have developed tiled display
systems (Hereld et al., 1999; Yang et al., 2001; Chen
et al., 2001; Krishnaprasad et al., 2004) which can
generate high resolution images and can fill up
users’ field of view with the images.
This paper proposes a tiled display system where
a high resolution image generates by binding images
obtained from multiple low resolution projectors.
Furthermore, we implement the educational contents
on the proposed tile display system.
2 SCREEN
One of the most important factors in virtual reality is
to convey the sense of reality to users. The sense of
the reality means that a user feels or experiences an
object in virtual world as the object exists in real
world. The one of the conditions to increase the
sense of the reality is to fill a user’s field of view
(FOV) with high resolution virtual images. Humans
have an almost 180
o
forward-facing field of view
(FOV) and 120
o
an effective FOV (Authur, 2000).
There are four major screens for expressing
virtual environment: (1) a wall type, (2) a cylindrical
type, (3) a dome type, and (4) a CAVE type. Since
the advantage of a tiled display system is to share a
virtual environment among users, we decided to
choose a cylindrical type screen which provides a
wide FOV. However, when virtual images are
394
Kim S., Park H. and Kim D. (2009).
A TILED DISPLAY SYSTEM FOR IMMERSIVE EDUCATION .
In Proceedings of the First International Conference on Computer Supported Education, pages 394-397
Copyright
c
 SciTePress

projected on the cylindrical screen, it is necessary
consider a complex calibration method for
generating continuous images. Another problem is
that the position of a target object is hard to compute
and to present on the cylindrical type screen.
lc
Figure 1: The shape and the size of the proposed screen.
Therefore, in this work, we implemented a folded
type screen which brings into relief the advantage
and supplements the disadvantage of the cylindrical
screen as shown in Figure 1. Since each sub-screen
in the folded type is flat, the proposed tiled display
system is not only easy to establish, to maintain, and
to repair but also easy to calibrate. In Figure 1, each
part (
①~⑧) is a projection area. In this symmetric
screen, the angle of refraction between the left sub-
screen (
①, ⑤) and the middle sub-screen (④, ⑧) is
120
o
. If the distance between a user and the screen is
1 meter, the field of view becomes about 160
o
.
3 SYSTEM ARCHITECTURE
GPU
GPU
Projector
Projector
Projector
Projector
Projector
Projector
Projector
Projector
PC
Figure 2: Hardware system architecture.
Figure 2 shows the hardware configuration of the
proposed system. The system was implemented with
a single PC and 2000 ANSI DLP projectors whose
resolution is 1024 x 768. Two graphic cards were
included in the single PC and each graphic card has
two graphic output ports. Each graphic output port
has a Graphics eXpansion Modules(GXM) which
can connect two visual displays. Therefore, our
system generates high resolution image by
connecting eight projection areas with a single PC as
shown in Figures 2 and 3.
(a)
(b)
Figure 3: (a) Screen, (b) arrangement of projectors.
4 CALIBRATION
The graphic simulations were carried out by a
program written in Visual C++ with direct X. As
mentioned above, we used 8 projectors to create
huge and high resolution images. Since projectors
can be moved or rotated by a small amount of
disturbance (for example, certain vibration, small
impact, and/or etc.), we overlapped the portions
which the projectors undertook as shown in Figure 4.
However, this installation causes an image to distort.
For compensating this distortion, we conducted
geometric calibration.
Figure 4: Overlapped Projection.
A TILED DISPLAY SYSTEM FOR IMMERSIVE EDUCATION
395

Figure 5 shows an example of geometric
calibration procedure when four projectors
employed in a tiled display. Figures 5(a) and 5(b)
show the images before and after the geometric
calibration, respectively. Consider the situation
where four projection sub-images are overlapped
and distorted according to the arrangement of
projectors as shown in Figure 5(a). These
overlapped and distorted sub-images need to be
adjusted to the compensated region (bold rectangle
portions (Figure 5(b)) through the calibration
method.
Figure 5: Geometric Calibration.
P
1
= (x
1
,y
1
), P
2
= (x
2
,y
2
), P
3
= (x
3
, y
3
) (1.a)
P’
1
= (s
1
,t
1
), P’
2
= (s
2
,t
2
), P’
3
= (s
3
, t
3
) (1.b)
(1.c)
For compensation, original projection portions
and the calibrated projection portions are divided
into triangles, respectively as shown in Figures 5(c)
and 5(d). After that we computed transformation
matrix from the triangle 1 (P
1
,P
3
, P
4
) to triangle 2
(P’
1
,P’
3
, P’
4
) using equation 1. In Figures 5(c) and
5(d), let’s define the coordinate values of P
1
, P
3
, P
4
as (x
1
,y
1
), (x
3
,y
3
), and (x
4
,y
4
), respectively. We also
define the coordinate values of P’
1
, P’
3
, P’
4
as (s
1
,t
1
),
(s
3
,t
3
), and (s
4
,t
4
), respectively. Figures 6(a) and 6(b)
show the results before and after the calibration
method, respectively.
Figure 6: (a) before and (b) after calibration.
5 VIRTUAL ENVIRONMENT
FOR EDUCATION
In the proposed tiled display system, we
implemented a virtual silicon island (VSI) where
users can learn semiconductor manufacturing
processes. Users arrived at the VSI and walked in
one of the buildings where they can study the semi-
conductor manufacturing process.
Figure 7: VSI authoring tool.
We developed a VSI authoring tool in order to
easily create, edit, and play semiconductor contents.
A user can insert or delete the semiconductor
manufacturing components through the VSI
authoring tool. As shown in Figure 7, the VSI
authoring tool consists of a screen control part(
①), a
calibration part(
②), and a contents control part(③).
The screen control part allows a user to determine
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396

REFERENCES
the size of images. The calibration part adjusts the
overlapped and the projective regions. In the
contents control part, multimedia objects based on
movie clips are displayed. Once multimedia contents
are registered in the contents control part, a user can
control and play them on the huge screen by just
clicking a mouse or pressing a keyboard. Figure 8
shows the semiconductor education contents based
on the proposed tiled display system.
Hereld, M., Judson, I. R., and Stevens, R.L., 1999.
Introduction to Building Projection-based Tiled
Displays. IEEE Visualization 1999.
Yang, R., Gotz, D., Hensley, J., Towles, H., and Brown,
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Chen, Y., Chen, H., Clark, D., Liu, Z., Wallace, G., and
Li, K.,2001. Software Environments for Cluster-based
Display Systems, IEEE International Symposium on
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Hereld, M., Judson, I. R., and Stevens, R. L., 2000.
Introduction to Building Projection-based Tiled
Display Systems, IEEE Computer Graphics and
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Krishnaprasad, N.K., Vishwanath, V., Venkataraman, S.,
Rao, A.G., Renambot, L., Leigh, J., Johnson, A.E.,
and Davis, B.,2004, JuxtaView - a tool for interactive
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Arthur, K. W., , 2000. Effects of Field of View on
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Figure 8: Semiconductor educational contents.
6 CONCLUSIONS
A virtual reality system provides the sense of reality
and becomes a more user-friendly interface than the
other systems. In this work, we developed the tiled
display system for educating semiconductor
manufacturing processes. Moreover, we conducted
calibration in order to compensate the distorted
image and to increase the sense of reality.
We are currently considering natural interaction
for effective lecture with the proposed platform.
Even though, the proposed system does not include
natural interaction (for example, gesture
recognition), it has the potential of an immersive
education platform as an effective tutor.
ACKNOWLEDGEMENTS
This work was supported by VTRC (Virtual
Training Research Center) in KUT (R-2008-0123).
This work was also supported by the Korea Science
and Engineering Foundation(KOSEF) grant funded
by the Korea government(MOST) (R01-2007-000-
20977-0).
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