Leaked Light Field from Everyday Material:
Designing Material Property Remained Light-field Display
Kazuki Takazawa1∗

Kenta Suzuki1
1

Shinji Sakamoto1
Yoichi Ochiai1

University of Tsukuba

2

Ryuichiro Sasaki 2

Yoshikuni Hashimoto2

AISIN SEIKI Co.,LtdACB

DE

Figure 1: Left: Our novel method make the everyday materials such as wood or stone to display surface. Center: Mirror based pinholedisplay that is indicating the time. Right: The material properties are shown in table 1.

Keywords: Display, Design, Fablication
Concepts: •Computing methodologies → Image manipulation;
Computational photography;

1Introduction

Conventional LCD displays do not use opaque materials, such as
wood or mirrors, as a surface. The surface materials for most displays are limited to transparent, smooth materials, because the surfaces need to transmit the backlight through the LCD and color
filter. However, these displays do not allow for the expression ofsurface texture; therefore, they cannot be built into an object without damaging its natural surface. We propose a new method thatchanges the display surface to allow for not only glass or plasticsurfaces, but also a wide variety of materials such as wood, stone,or mirrors, in order to overcome this weakness of conventional displays.
In this paper, we develop a new display device called a pinholedisplay that uses everyday materials such as wood, stone, or mirrors. The surface materials used in our method are processed intoplates and drilled 19,200 pinholes with 100 µm diameter. Rays
from backlighting can be seen through the surface as an indicationof the presence of the holes. The user is only able to see the original material, because the holes are small enough to be invisible tothe human eye. The plates work as a display only when exposed tothe backlight. We can embed the display in a floor, wall, or mirror
without damaging their natural surfaces.
∗ e-mail:1220kazu1412@gmail.com
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SA ’16, December 05-08, 2016, , Macao
ISBN: 978-1-4503-4540-8/16/12
DOI: http://dx.doi.org/10.1145/3005274.3005313

It is possible to generate different rays depending on the viewing
angle, based on the ray selectivity of the pinhole. It is thus madepossible to provide different information to multiple viewers. We
can create a stereoscopic 3D view based on a parallax barrier [Ives1903] to present different images to the right and left eye. Also,
the image can be changed with the distance of the viewer from thedisplay. Therefore, we are able to achieve various user interactions
from the pinhole-display.
Table 1: Material Properties
Material
Wood (B)
Stone (A)Genuine leather (D)Synthetic leather (E)Mirror (C)2

Number of pinhole
520(26 × 20)
520
19,200(160 × 120)
520
19,200

Diameter
200µm
200µm
200µm
200µm
100µm

Processing method
DrilledDrilled
CO2 Laser
CO2 Laser
Femtosecond Laser

Design Method

The pinhole is a small hole, which is drilled into the object. It
has been used in conventional methods such as the Coded Lens
[Sekikawa et al. 2014] and the Pinlight Display [Maimone et al.
2014].The F-number of light passing through an ideal pinhole is infinite. In our display, we focus on the effect of the pinhole, which
can block out light. A pinhole of about 100 µm is difficult to observe with the naked eye, and as such one cannot identify pinholes
in the display plate. By adding this feature to surface materials,
even those not typically used as displays, it is possible to cause thesurface to act as a display only when the power is turned on.
We make three types of pinhole arrays for our display: One is madefrom a mirror, one is made from a wood-style plate, and one is madefrom a stone-style plate. To make the mirror pinhole array, we use
femtoseconds lasers to cut the pinholes. To make the stone-stylepinhole array, we use a typical laser cutter and drill. In accordancewith the machine’s limit, the pinhole size is 200 µm.
When we observed through the microscope both pinhole processing with femtosecond laser and one machining with drill and normal laser, we found out difference in precision. Pinhole processing

(a)

(b)

(c)

Figure 2: The design example that using pinhole array. The Dash board display(a). It’s possible to indicate for the wood style board or
furniture without damaging to surface materials Utah teapot is shown on wooden board (b). These applications are using Multi-viewpoints
Display. The application example of mirror pinhole array (Infinite AR)(c).

with femtosecond laser is shapely and its edge is smoothly. On theother hand, we learned that pinhole machining with drill and normal
laser is distorted its shape by machine and its edge become fluffed.
Additionally, depending on the material to be used, the result is different. Using a laser beam machine in a normal wood sear aroundthe hole. This looks bad because leave a working mark. We use
woodgrain and stone style pinhole and veneer made of melamine
board. Then when we process a mirror with normal laser beam,processed part has thermal denaturation. So we use a femtosecondlaser. It can process without thermal denaturation [Chowdhury andXu 2003]. List of material is shown in table1.

3

Application

In the case of a conventional mirror, it is impossible to indicate
highlighting on a mirror with two or more viewpoints. We consider
the case of several people looking at a mirror at the same time.
When one user looks at the highlighted mirror from angle A, while
another user looks at the same mirror from angle B, the highlights
is shift from the reflected image on a conventional mirror. Thisphenomenon happens because the highlighting of the mirror is performed in the same way regardless of the viewing angle. In the caseof a mirror pinhole-display, it is possible to change the information
indicated depending on the viewing angle. We can thus highlightthe same thing when many users look at the same mirror by indicating different information depending on the viewing angle of theuser.
We assume that a mirror display with pinholes is used in a situationsuch as the rearview mirror of a car. When one user looks at themirror from the driver’s seat and another user looks at it from thepassenger’s seat, it is impossible to highlight the same reflected image, because the reflected image is different at the two viewpoints
on the conventional mirror.
The pinhole mirror display can present a light-field that makes it
possible to see the same thing from point of view of the driver andthe passenger. In this way they are able to share information about
dangerous situations or target items. We consider the case where
the object is at a distance l away from the mirror. In this case, weobserve a mirror at a location a distance W away from the object
and a distance L away from the mirror. The location x where thereflected image is seen can be expressed by the following formula.
lx=W ∗L+l(1)

When a light field is designed using this calculation, it can be assumed that the real light field and the imaginary light field exist
across the pinhole mirror. The ray issued from the reflected image
in the imaginary light field passes the mirror surface, and projects
into the real light field. The light field of the ray from the pinhole isdesigned according to the projected ray in the real light field. Thismakes it possible to produce a light field that emphasizes the object
from every angle at which it is seen. If we design according to thelight field in this way, the only variable required for the calculation
will the location of the object. If the location is measured correctly,
the highlighting of a multi-aspect moving object becomes possible.
We develop a system using the single depth camera that measuresthe location of the object and shows the pattern on the LCD display in order to compose a light field. The location of the object
acquired using the single depth camera is substituted for the abovementioned arithmetic expression. This is achieved by adjusting thepatterns according to the movement of the object‘s calculated location for where the reflected image appears in the mirror. When thepinhole mirror device is fixed, we can highlight the object even if
both it and the viewpoint are moving (Figure 2).

4Conclusion and Future WorkIn this study, we propose a novel method allowing the use of opaquematerials such as wood, stone, or mirrors as display surfaces. The
100 µm diameter pinhole is invisible to human eyes, and as suchappears only when the pinhole-display is switched on. Therefore,
we are able to extend the list of potential display surfaces to include everyday materials such as wood or stone. In addition, we
have realized glassless 3D and a display that depends on viewing
angle, based on the ray selectivity of the pinhole. The Infinite AR
mirror pinhole array can be used to highlight the same object fromdifferent points of view.
We may be able to use this novel display as a touch panel to embed capacitive sensors behind the surface material. We would liketo further examine the application of this technology to locations
such as furniture or car interiors.

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