ARScope
Takumi Yoshida ∗Shinobu Kuroki †Hideaki Nii ‡The University of Tokyo

Naoki Kawakami §Susumu Tachi ¶Figure 1: Application Examples of ARScope.

1Introduction

Head-mounted Projector
with a Built-in Camera
Camera

ARScope is a novel visual interface for various applications of augmented reality. A user views the world through a handheld device
that has a shape similar to that of a magnifying glass or a crystalball. When the user holds the device over an object, the image of theoccluded part is displayed on the surface of the device seamlessly
as if the surface of the device were transparent glass. The displayed
image can be edited freely by using some of the techniques that areused for augmented reality. For example, a red apple can be colored
blue, or animated CG characters can be made to appear suddenly.

2Features

In order to desplay the image of augmented reality applications,various techniques have been researched [Kato and Billinghurst1999][Wagner et al. 2005]. The two typical devices used in thesetechniques are a head-mounted display and a handheld display suchas a PDA. There are some difficulties associated with the use ofthese devices. One of them is the problem of tracking the user’sviewpoint. In order to create an appropriate image for the user’s
arbitrary viewpoint, the application needs a head-tracking sensor orsome markers. The other problem is the seamless connection between the displayed image and the real environment. Therefore, wepropose ARScope, a device that aims at solving these problems.
Our proposed system has the following three features that have notbeen achieved by the conventional method.
Mobility: Users can look anywhere from an arbitrary viewpoint
without the use of any head-tracking device or markers.
Seamless connection: The image displayed on the device and thereal environment are connected seamlessly.
Multiple users: Two or more user’s can use the same device at thesame time since different pictures are presented in different
directions.
∗ E-mail:takumi yoshida@ipc.i.u-tokyo.ac.jp† E-mail:shinobu kuroki@ipc.i.u-tokyo.ac.jp‡ E-mail:hideaki nii@ipc.i.u-tokyo.ac.jp§ E-mail:kawakami@star.t.u-tokyo.ac.jp¶ E-mail:tachi@star.t.u-tokyo.ac.jp

Retro-reflective Material

Figure 2: System Configuration.

3Principle

ARScope employs a method for optical camouflage using a retroreflective projection technology [Inami et al. 2003]. Figure 2 shows
the system configuration. The proposed system comprises a handheld device and a head-mounted projector. The handheld device iscovered with a retro-reflective material, and a superimposed image
is projected onto it from the projector.
Both devices have built-in cameras. Cameras placed on the innerside or the reverse side of the handheld device capture the background image. Meanwhile, a camera built inside the projector captures the image of the user’s view. By matching the feature points
between these two images, a homography matrix between the twoimages is computed. Then, a projective transformation is applied tothe background image in order to generate image that is suitable forthe user’s viewpoint. This technique enables the ARScope to display an image of the area occluded by the handheld device without
the use of any head-tracking device or markers.

4Conclusion

We have proposed and implemented the ARScope. In the future,we will improve the processing speed and the performance of thisdevice.

References
I NAMI , M., K AWAKAMI , N., AND TACHI , S. 2003. Optical camouflage using retro-reflective projection technology. In Proc. ofthe 2nd ISMAR 03.
K ATO , H., AND B ILLINGHURST, M. 1999. Marker tracking andhmd calibration for a video-based augmented reality conferencing system. In Proc. of the 2nd IWAR 99.
WAGNER , D., P INTARIC , T., L EDERMANN , F., AND S CHMAL STIEG , D. 2005. Towards massively multi-user augmented reality on handheld devices. In Proc. of the 3rd Pervasive 2005.

Copyright is held by the author / owner(s).
SIGGRAPH 2008, Los Angeles, California, August 11–15, 2008.
ISBN 978-1-60558-466-9/08/0008