The Mid-Air FogScreen and User Experiences

The Mid-Air FogScreen and User Experiences

Ismo Rakkolainen, Satu Jumisko-Pyykkö
DOI: 10.4018/978-1-60960-762-3.ch036
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The “immaterial” FogScreen™ is an emerging display technology that enables high-quality projected 2D images in mid-air. It also appears dry and non-existant to touch, so reaching or walking through the image is possible. It is becoming widely used in many settings and can also be extended to become a stereoscopic or virtual reality mid-air screen. This chapter consists of two major sections. The first section describes the basic mid-air screen technology and its 3D and VR extensions. The second section describes our user experiences and lessons learned with them when using mid-air screen.
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Futuristic visions of mid-air images are frequently seen in TV commercials and sci-fi movies. Illusions of images floating in free space or 3D images that have real depth can be generated in a variety of ways, but most of them are not truly in thin air. Volumetric displays do create real 3D images instead of a 3D illusion, as the light is emitted from the actual 3D positions, but the images are in a confined display volume and interaction with them is limited. Virtual environments try to create illusions of virtual objects in an immersive environment, whereas augmented reality adds synthetic objects to the real world.

The patented FogScreen™ (Palovuori & Rakkolainen 2002, Palovuori & Rakkolainen 2004, FogScreen 2010) mid-air projection screen is an emerging display technology that enables high-quality projected images hovering in thin air, which the viewer can reach or walk through (Figure 1 left). It is a break-through technology, literally! It is basically a 2D screen, but it can be extended to a stereoscopic display. If 3D tracking of a viewer is used, it becomes a walk-through virtual reality display, which augments virtual mid-air objects into real environments (Figure 1 right). We will describe the technology in the next section of this paper.

Figure 1.

The FogScreen mid-air display is an intriguing walk-through experience. The device is suspended e.g., from a truss and a projector is placed behind the screen (left). A 3D model of hand bones on a virtual reality FogScreen (right).


The mid-air display is somewhat unusual, and also user experiences are different from other displays. The mid-air effect intrigues audiences and the user reaction is usually very positive. Due to the “immaterial” nature of the display, the user interface design requires also some extra attention and provides some new user interface opportunities. We will discuss our lessons learned in the later section of this paper.


The Fogscreen™ Mid-Air Display Technology

There are numerous projection screens using water, smoke, fog or cryofog (liquid nitrogen), which have been used as a special effect in art and entertainment. The earliest example is the Ornamental Fountain (Just, 1899) dating back to the end of the 19th century. More recently, fog and water screens such as Jeep Waterfall (Jeep Waterfall, 2010) and Disney’s Fantasmic show (Disney, 2010) create impressive screens for large audience. These screens are often wet, or the fidelity of the projected images is low. If fog is used, it disperses rapidly due to friction and dynamic pressure difference in the flow, which disrupts the desired smooth planar surface and severely distorts the image.

Key Terms in this Chapter

FogScreen: A mid-air, walk-through display. The screen consists of thin mist, which enables to walk or reach through it.

Stereoscopic display: A display which produces an effect of depth for the viewer by means of stereo image pairs and active (shutter) or passive (colored, polarized etc.) glasses.

Embodied interaction: Interaction between user and artifacts which contains creation, manipulation and sharing of meaning.

User Experience: User experience is constructed in interaction with system and is influenced by user’s characteristics, system characteristics and the context of use. User experience is understood as a wider concept than fulfillment of instrumental needs with system (e.g. usability).

Usability: The extent to which the product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction (ISO 9241-11, 1998).

Autostereoscopic display: A display which produces an effect of depth for the viewer without any glasses.

3D display: A display which gives an effect of depth for the viewer. A set of technologies can be used, including holography, volumetric, multi-view or stereoscopic displays.

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