User Interface by Real and Artificial Shadow

User Interface by Real and Artificial Shadow Huichuan Xu* Osaka University

Ichi Kanaya* Osaka University PRESTO, JST

Fig. 1 Shadow Painter by Real Shadow

Shinsaku Hiura** Osaka University

Kosuke Sato** Osaka University

Fig. 2 ‘Click and Drag’ by Virtual Shadow with IR Light Source

1 Introduction

2.2 IR Light Source for Artificial Shadow

This poster proposes concept and prototype of an intuitive user interface based on shadow for indoor environment. Shadow is a common phenomenon in our daily life where there is light source. It always exists but we ignored the potential of shadow for connecting digital and physical world. There are several merits of shadow interface: first, shadow is a daily life familiarity and it builds a natural bridge between digital and physical worlds; second, the shadow based interaction system is simple and does not require expensive devices; third, shadow itself is a strong and natural visual feedback cue for the user to take good command of applications.

Fig. 2 shows another application based on IR light source. An independent IR light source is located behind the user. The projector is installed on the ceiling of the room so that the user’s body will not block the light from projector. A camera of strong IR sensibility is installed with an IR filter so that the invisible shadow can be robustly captured. The projector will project an artificial shadow which exactly aligns with the invisible IR shadow.

In Spatial Augmented Reality (SAR) environment [1], our daily life working space can be extended by projectors to every corner of the room. However, traditional ‘direct-touch’ style interfaces such as DigitalDesk [2] still limit us within the desk area. So, designing spatial interaction method is an important and necessary task.

2 System Setup Basically, this system consists of light source, projector, camera, pc and user. There are two choices for light source: visible light source and IR (infrared, invisible) light source. 2.1 Visible Light Source for Real Shadow Fig. 1 shows an application based on visible light source. The projector is installed above the desk and it also acts as a light source. The camera is installed at one side of the desk so that it can catch the projected shadow while not blocked by user’s hands. In Fig. 1, the user is drawing picture on the desk by his or her shadow.

*email: {iamxhc, kanaya}@sens.sys.es.osaka-u.ac.jp **email: {shinsaku, sato}@sys.es.osaka-u.ac.jp

3 Discussion Selection of light source: the authors found from their experiments and users’ feedback that both prototypes have their own advantages under different situations. Real shadow derived from visible light is of more intuitiveness and it is usually interesting for the user to interact his/her real shadow with virtual objects while the virtual shadow derived from IR light is more flexible in color, pattern and transparency Future applications: possible applications include: ! Assistance to presentation based on projector ! Entertainment ! Media art ! Educational interaction in museums ! Touchless interface in hospitals ! Remote control inside intelligent house The authors have demonstrated that shadow has possibility to realize simple but effective interface between human and computer systems.

Reference 1. Oliver Bimber and Ramesh Raskar. 2004. Spatial Augmented Reality. A.K. Peters. 2. P. Wellner. 1993. Interaction with Paper on the DigitalDesk. Communications of ACM 36(7), 87-96.