bubble cosmos

A system that produces real bubbles containing white smoke and projects CG images onto them. When users break the bubbles, they produce changes in the visual stimulus and sound effects.

Enhanced Life
bubble cosmos provides interactive entertainment in which users enjoy viewing and breaking bubbles of CG images drifting in the air. By actually touching and breaking these physically beautiful bubbles, users are surprised by a novel experience that is much different from conventional artificial entertainment.

Goals
Using smoke-containing bubbles as screens, the system produces visual effects never before experienced. Since the CG image is projected not onto the bubble surface but onto the smoke the bubble contains, it seems as if the image is actually inside the bubble. As the camera tracks the CG-projected bubbles, users perceive images drifting through the air along with the bubbles. The system is able to determine when the bubble disappears naturally or is broken intentionally, and timed sound effects produce an unexpected burst of explosion. In addition, the image is altered to produce the visual effect of swaying that is unique to spreading smoke.

Innovations
By automatically detecting the position and status of a bubble, bubble cosmos can accurately project a CG image onto a single location and can change the image while providing sound effects. To detect a bubble drifting in the air, the system processes images photographed by a fixed camera. The images are first converted into grayscale, and a moving object is detected from inter-frame differences. Although it is difficult to detect the shape of an ordinary bubble, the smoke inside enables clear detection. Then noise is eliminated by Gaussian Pyramid processing, and images binarized with an appropriate threshold are labeled to judge whether a bubble exists in the sequence. For this judgment, several parameters reflecting the bubble characteristics are used. The bubble position and size are detected at the same time. Whether the bubble has broken or not depends on whether the same bubble is in the next frame.

A CG image is projected onto a bubble from a projector just under the fixed camera. Since the optical axes of the camera and projector are very close to each other, projection onto a bubble can be realized by conversion from simple camera coordinates to projector coordinates.

A bubble generator automatically generates a few bubbles about every 15 seconds. Smoke is generated by a smoke machine that heats a solution delivers the smoke to the bubbles.

Vision
bubble cosmos offers a new presentation platform. For example, the system could be used as a beautiful interactive display for advertising. A corporate logo or product name could be projected onto a bubble, and a commercial message could be displayed on a separate screen when a bubble is broken.

The system could also be used as an educational tool for small children. For example, the letter "D" could be projected onto a bubble and a dog displayed along with a "bow-wow" sound when the bubble is broken. When this possibility was tested in trial experiments, children were deeply interested in the images and surprised at the sound effects when a bubble was borkeen. The system worked effectively as an educational tool.

Contact
Masahiro Nakamura
University of Tsukuba
nakamura (at) graphic.esys.tsukuba.ac.jp

Contributors
Go Inaba
Jun Tamaoki
Kazuhito Shiratori
Jun'ichi Hoshino
University of Tsukuba