WAVE is a novel, low-cost, and simple method for forming a superior quality physically penetrable fog display. It is a break-through technology, literally! This work has international patents pending.

The basic components of the screen are a laminar, non-turbulent airflow, and a thin fog screen injected into and inside a laminar flow. Created this way, the fog screen is an internal part of the laminar airflow, and remains thin, crisp, and protected from turbulence.

An early prototype was constructed with honeycomb paper as a low-cost laminar airflow generator. Liquid nitrogen formed a very dense and white fog with warm water. If the mean diameter of fog droplets is small, this so-called dry fog does not wet clothes or harm equipment and appears dry to the touch. When the screen is formed, images can be either rear- or front-projected onto it.

Despite of being a very early prototype, the experimental fog screen already proves the operating principle with excellent results. Both the laminar airflow and the fog creation can surely be enhanced with more experimentation on various materials and methods of construction.

Figure 1. Images projected onto the penetrable fog screen.

Figure 2. Images projected onto the walk-thru fog screen. The turbulence is due to poor fog feeding construction.
The "ghost hand" on the fog screen seems to float in the air, while the second faint hand on the wall behind is also visible.

MPEG-2 video
MPEG-1 video

Applications
The fog screen enables many novel applications for both indoors and outdoors. Mixed reality and immersive projection technology can use CAVE-like virtual rooms with fog walls, making them effectively “virtual virtual rooms”. The fog screen is non-breakable, which enables safe gaming, combat exercise or training, and non-supervised public presentations. It also enables the audience to enter and exit rapidly through the walls into virtual environments, which may be even sequential. Interesting applications could include walk-thru advertisements on shops or malls, or a walk-thru screen entrance to a theme park.

Non-planar surfaces like sharply curving cylindrical shapes are also possible. One possible extension to the method is to make 3D fog shapes, if a suitable computer-controlled fog nozzle matrix is used. Light, mobile, and large screens, table displays or virtual rooms for offices can be set up easily.

Instead of using blowers, natural wind could be used to generate the airflow. If the laminar unit and fog nozzles are suspended over a bridge or such constructions, enormous vertical and/or horizontal fog screens become possible under suitable weather conditions.

Reference
RAKKOLAINEN, I., and PALOVUORI, K. 2002. WAVE – A Walk-thru Virtual Environment. IEEE VR 2002 Conference, Proceedings of Immersive Projection Technology Symposium 2002, Orlando, FL, USA, March 24-25, 2002. PDF

Contact
Ismo Rakkolainen, Tampere University of Technology, Finland
Tel. +358-3-31153843
ira@cs.tut.fi

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