WISS 2019

OmniLantern: A Portable Omnidirectional Projector-Camera
System in the Shape of Lantern
Ruopeng Xu∗

Toshiki Sato†Hideki Koike‡

Abstract. We present a lantern-like projector-camera system named OmniLantern, which is composedof an ultra-wide-angle lens and a projector-camera unit. Unlike other existing projector-camera systems,
OmniLantern can detect the objects and project to all directions with one projector-camera unit. We
introduced the design concept of the OmniLantern firstly. Then we showed our implementation of thehardware and the software. Finally, we developed some applications of this system and discussed thelimitations and future work.

1Introduction

There are a lot of ways of enhancing the users’
vision experience using a wide-angle lens. For
instance, Maeda et al.[1] show a tabletop system with an omnidirectional lens and Kasahara’s
HeadLight[2] is a wearable projector system witha large field-of-view. However, the existing works
have limitations. Maeda’s work is set under thetable and it is hard to be moved. HeadLightis designed for the first-person perspective using
and does not support multiple people using.
That’s why we present OmniLantern, a novel
projector-camera system with an omnidirectional
lens. We combined the projector, camera, andwide-angle lens together so that OmniLantern
can be a movable system. The users can take theOmniLantern walk around, share the information with others, or put it wherever they want,
which is impossible with the normal projectorcamera system.
Considering this system is a novel system andthe users may be confused about how to use it,
we also show a lantern metaphor for it. The
appearance of the OmniLantern likes a lantern,
and it can be used as a lantern as well.

2Implementation

We developed the design of the OmniLantern
shown in Figure 1. OmniLantern is composed ofa 37mm Opteka 0.3X ultra fish eye lens, a small
LB-UH6CB laser projector, a CM3-U3-13Y3CCopyright is held by the author(s).
Tokyo Institute of Technology†
Japan Advanced Institute of Science and Technology‡Tokyo Institute of Technology∗Figure 1. Hardware composition and principle

S-BD Chameleon3 camera, a half-mirror from
Edmund Optics with reflection-transmission ratio 20/80, and the 3D-printed case.
To make the users easy to understand how
to use OmniLantern, we designed two specialparts. Firstly, we added a lampshade to the OmniLantern, like the lampshade of the real lantern.
When OmniLantern is equipped with the lampshade, OmniLantern is a small size cylindricaldisplay. On the other hand, when the lampshade is moved, contents can be projected toother surfaces with AR markers. These two different modes make the system more flexible tobe used.
Secondly, in order to realize the portable system, we designed two diﬀerent handles for thesystem. The bigger handle is used for grabbing
OmniLantern. Users can easily hold the handle and walk around. The smaller handle is for
hanging OmniLantern on the top. Using thesehandles can let the users understand the usageof a novel interactive device naturally. Figure 2

WISS 2019shows the prototype of OmniLantern.

Figure 2. Prototype of OmniLantern, users canput it on table(a) or hold it(b)In the Navigation Mode, when users hold thehandle of the lantern and walk, OmniLantern isable to project the navigation message onto anysuitable surface around the user such as floor orwall as shown in Figure 3(c).
Figure 3(d) is Hanging Mode, users can hang
the OmniLantern on the top and project contents on the table, floor or the walls around.
They only use one projector and can realize spatial augmentation.

For each target of the projection surface, weattached an AR marker on it, so that the markers will tell the projection content and surface
size. We detected the pose of the markers fromthe image, and use marker’s pose to distort theprojection content, and project it to the corresponding positions.

3.2 Extended function
In addition to the mentioned modes, there aremany other functions based on the basic modes
as shown in Figure 3(e) to Figure 3(h), such as
highlights the target for searching the things,
provides the SNS or entertainment content whenusers’ hands are busy, augments small space, andworks as night light.

34Application

We discuss some applications that can utilize
the unique advantages of the OmniLantern inthis part, including four basic modes and fourextra functions.
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PM15Tent
A180°(a) Light (c) Navigation(e) Searching (g) Augmentation(b) Table (d) Hanging(f) Free hands (h) Night lightASNSNews180°AB

Figure 3. Shows the basic modes from (a) to(d) and extended functions from (e) to (h)3.1 Basic modes
The first mode is called Light Mode. Whenthe users put on the lampshade, OmniLantern isa cylindrical display that can be placed on thetable. It shows some necessary information forusers such as time or to-do list or be a normallight.
What’s more, users can take oﬀ the lampshadeand put it on the table, which is called TableMode. For example, when people are working
with computers opposite each other, OmniLanternprojects the display content on the back of thecomputer. This mode can be used in teamwork
or meeting.

Discussion and Conclusion

We present OmniLantern, a novel device thatcan realize the spatial projection with one projectorcamera unit. This design could solve the problems of multiple camera calibration and can also
make the whole system portable.
In our current prototype, we used AR markers for determining the pose and location of theprojected content, which is unnatural for users.
To overcome this problem, we could use invisible markers with infrared absorbing ink and IRcamera.
What’s more, as a portable system, we are going to add the positioning functions to OmniLantern, so that it can decide which mode touse based on the current location.
Last but not least, OmniLantern needs moreinteractive ways such as gesture interaction, weare going to develop simple gestures for the users
to operate the system.

References[1] Maeda, K., Piekenbrock, M., Sato, T., & Koike,
H. (2018, November). A Tabletop System Using
an Omnidirectional Projector-Camera. In Proceedings of the 2018 ACM International Conference on Interactive Surfaces and Spaces (pp. 311314). ACM.
[2] Kasahara, S. (2018, August). Headlight: egocentric visual augmentation by wearable wide projector. In ACM SIGGRAPH 2018 Emerging Technologies (p. 10). ACM.