Colorful Touch Palette
Yuki Hirobe*
Takumi Yoshida**

Figure 1: Concept drawing

Shinobu Kuroki*
Kouta Minamizawa†

The University of Tokyo

Figure 2: “Tactual Cap”

1. Introduction
Previously, pictures were painted using tools such as crayons oreven by hand. Surfaces such as canvases or walls, provided thetactile sensations of the drawing surface while painting. However,this tactile experience has got lost because of advances incomputer graphics software. Besides, a conventional multi-touch
interface [1] can not provide tactile sensation. We propose a novel
interactive painting interface called “Colorful Touch Palette” thatmay help us to rediscover our creativity. The user can touch thecanvas having the electrode, select or blend tactile textures of theirchoice, draw a line, and experience the tactile sensations ofpainting as shown in Figure 1. Various tactile textures can becreated by blending textures as paints. This interface can be used
to design complex spatial tactile patterns for haptic-friendlyproducts. Moreover, this system can be potentially used to create
novel tactile paintings.
2. Technical Innovations
To realize the concept of this interface, following features arerequired.
(1) Providing various types of tactile sensation that the user canrecognize comfortably.
(2) Creating new tactile textures by blending original textures.
(3) Providing tactile feedback according to the motion andposture of the finger.
With regarding to feature (1), the previous electro-tactile
stimulation system [2] could provide only uniform rough texturesand could not provide grating convex patterns with a resolution
higher than the electrode interval. We improved the technique ofelectro-tactile stimulation of spatial patterns, and we archived
various patterns of tactile sensations. We provided various degreesof roughness by changing the intensity and controlling thedistribution and variances of each electrode. We also virtually
increased the spatial resolution by changing the stimulus points
faster than the fingertip movements as occasion demanded, insteadof synchronizing both movements.
We designed the blending method of tactile textures for realizing
feature (2). It is known that each polar stimulus can produce
different sensations: sense of vibration by anodic stimulus andsense of pressure by cathodic stimulus [3]. To calculate the stimuliof the blended tactile textures, we defined a pressure model
Mp(x,y) and a vibration model Mv(x,y) for each tactile texture ande-mail: {yuki_hirobe,shinobu_kuroki,katsunari_sato,takumi_yoshida}@ipc.i.u-tokyo.ac.jp†e-mail: {kouta, tachi}@tachilab.org*

Copyright is held by the author / owner(s).
SIGGRAPH 2010, Los Angeles, California, July 25 – 29, 2010.
ISBN 978-1-4503-0210-4/10/0007†Katsunari Sato*Susumu Tachi†

Keio University

Figure 3: “Touch Palette”

Figure 4: “Texture Canvas”(a) 2D canvas (b) 3D canvas

described a texture as T(Mp,Mv). When the user blends two
different tactile textures (T1(Mp1, Mv1) and T2(Mp2,Mv2)), theblended texture (Tb(Mpb, Mvb)) can be calculated as follows:
Mpb(x, y) = Mp1(x, y)∧Mp2(x, y)Mvb(x, y) = Mpb(x, y)∧(Mv1(x, y)∨Mv2(x, y))
For feature (3), we implemented temporal patterns ofelectro-tactile feedback. In previous works, the special distributionof electrode intensities in the finger pad was not controlledaccording to the human motion. Here, we measured the movement
and the contact state of the finger, and used the data to provide
tactile feedback according to the velocity and pressure of thefinger.
3. System Configurations
This system is composed of a “Tactual Cap”, “Touch palette”
and “Texture Canvas”.
“Tactual Cap”: a cap shaped device, as shown in Figure 2, thatconsists of a high-density electrode matrix for providing tactile
feedback, a pressure sensor for estimating the contact state of thefingertip, and tracking markers for detecting the fingertip posture.
“Touch Palette”: a palette shaped display that consists of a touchpanel. Several types of visuo-tactile textures called “tactile colors”
are arranged as shown in Figure 3.
“Texture Canvas”: we propose two types of canvases – a 2D
canvas and a 3D canvas, as shown Figure 4. The 2D canvas
consists of a touch panel monitor mounted on an easel. It is used
for painting a tactile picture. The 3D canvas consists of a solid
screen, a projector, and motion tracking cameras. It is used forsurface prototyping.
The user blendes the tactile colors together on the Touch Paletteusing a finger with the Tactual Cap, which creates various tactile
colors. Then the user touches and draws a visuo-tactile painting on
the Texture Canvas at will with tactile feedback. The user canappreciate the visuo-tactile picture he/she painted on the basis of
the tactile feedback. The painted tactile pictures are archived, andother users can enjoy them with stimulating tactile sensations.
References[1] Han, J.Y. 2006. Multi-touch interaction wall. ACM SIGGRAPH
Emerging Technology.
[2] Kajimoto, H., Inami, M., Kawakami, N., AND Tachi, S. 2004
SmartTouch: Electric skin to touch the untouchable. IEEE CG&A
24:36-43[3] Kajimoto, H., Kawakami, N., Maeda, T., AND Tachi, S. 2001
Electrocutaneous Display as an Interface to a Virtual Tactile World,IEEE Virtual Reality Conf., Yokohama,Japan .