論文

We propose the concept and implementation of a graphical information hiding technique for interactive tabletops where users can view the information by simply casting real shadows. We placed three projectors (one in the rear and two in the front) in such a way that the rear one projects graphical information onto a tabletop surface, and the front ones project a complementary image, so that the combined image displayed on the surface becomes uniformly gray, thus hiding the information from the viewer. Users can view the hidden information by blocking the light from the front projector, revealing the complementary image that is being projected onto the occluder. We use the other front projector and polarization filters to make the complementary image projected onto the occluder also uniformly gray. Because the technique completely relies on optical phenomena, users can interact with the system without suffering from any false recognitions or delays. © 2011 ACM.

This article introduces a system we are developing that provides a first-person-view experience to users. It is aimed at preparing athletes to engage in sports competitions by enabling them to experience game situations from their own point of view before the game. The use of video has rapidly become popular in the sports field in various ways such as for scouting the opposing team before the game. Such videos are usually captured from a position different from that of players while they are playing the game. Thus, they cannot simulate the game very well. Our system provides a virtual reality-based firstperson-view experience by using information captured or measured from locations that will not disturb the game. We describe in this article how our system worked in a trial with a professional baseball team.

Shadow is widely researched as a user interface for manipulating graphical information on large displays. The shadow of one's fingertip is used as a pointing cursor whose position and size (i.e., gain and reaching area) can be intuitively adjusted, because one thoroughly comprehend the shadow's perspective projection behavior. The goal of this research is to allow a seated user, who cannot sufficiently move his/her fingertip, to manipulate the shadow cursor. We achieve this by relaxing the perspective constraints, i.e., applying weak perspective projection model. Through an experiment, we confirmed that the pointing performance of seated users is improved in the proposed method compared with the conventional method. Specifically, the users completed pointing tasks 25.1 % faster with 54.2 % fewer errors when the target size was small, 34.5 % faster with 64.2 % fewer errors when the target size was medium, and with 58.3 % fewer errors when the target size was large.