- Himalaya's Head:Disturbed Visual Feedback in an Interactive Multi-User Installation
Himalaya's Head is a multi-user installation that explores the phenomenon of mismatches between images on the retina and head movements. Participants experience the sensation of things not happening at a normal pace due to the loss of the natural balance between their actions and retinal feedback.
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The piece questions the way people interact with their environment. We perform hundreds of actions unconsciously. Normally as we move around, for instance, we are hardly aware of the retinal flow produced by head movements. Sometimes the experience of visual illusions that make us wonder about the way in which we perceive and process our environment can reveal the mechanisms of the brain. So we decided to blow up one such mechanism and distort it.
In Himalaya's Head, a 3D snowball connected via sensors to a participant's head movements moves more slowly and in a different way than the participant expects, giving him or her the feeling of moving his or her head through thick syrup. This sensation results from the damped forced harmonic algorithm controlling the movements of the snowball, and also because, as speed is relative, the reference speed is set by a moving landscape while the head remains still.
The Head-Tracking System
Participants wear lightweight, cardboard head beacons, each equipped with three infrared LEDs. A web cam positioned above the participants captures the movement of the LEDs, and a computer uses this information to calculate participants' head positions and to direct a 3D world and its dynamic 3D objects in real time. The result is projected on three adjoining screens (Fig. 1). The head-tracking system measures the horizontal and vertical rotation and position of up to 10 participants simultaneously. They can walk freely around the space, and the system keeps up with who is controlling which 3D object.
Thin Air or Thick Air?
Each participant gets control over one snowball, which reacts to the participant's head movements, creating the sensation of floating through the landscape (Color Plate C No. 2). As all the snowballs are identical, the challenge is to find out which snowball is under whose control.
Playing with the snowballs and letting them move is a game in itself. The snowballs can float happily dreaming or chase each other in friendly or aggressive ways. The tranquil effect of the floating is disturbed when the participants are challenged to knock down a virtual mountain guide in an adrenaline-stimulating game, forcing them to choose between experiencing the hypnotic world or the gaming world. [End Page 17]