> Motivation
> Example Movie
> Comment
> Conclusion
> Related Experiments
> Setup


Performance Photo

Screenshot

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Motivation

The person on stage controls a video spot on the screen, which shows a time reversed replay of the past within a defined time frame. Every movement visually provokes a countermovement. Continuing the idea of the time-delayed video as a metaphor for memory, reversing the video virtually backtracks the memory. The dancer can selectively reverse the motion of parts of his visual representation and link it to his actual movement. The reversibility of motion should reveal a recognizable motivation for the choreography.

 

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Example Movie

Stage View
Computer Image
While the dancer is moving through a sequence, short parts of this sequence are seen in reverse inside the circle surrounding the sensor on the left hand. After a few seconds the reversed image disappears and shortly after that a new backwards playback starts.

 

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Comment

The short movement fragments that are replayed in reverse become a counter-partner while improvising. This counter-partner is reflecting the movement that has just been performed and becomes visible only when the sensor is positioned at the very place where the movement happened.

The double exposure of the current and the just-passed-reversed movement creates an unusual kind of movement memory. The timing of the backwards motion appears sometimes jerky and disturbing. After observing each other several times in this experiment our eyes got quicker at reading the counter-timings and managed to separate more easily the current and past motion.

The awareness of ones movements being reversed in the computer-generated image influenced also the decisions of how to move in this experiment. This awareness resulted in the dancer deciding to make quick changes from moving towards the front and then the back as well as repeating and holding stops.

 

 

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Conclusion

This experiment works the best, if small motion units are synchronized with the start of a reverse replay. The frequency in which the replay starts subdivides the choreography rythmically into pieces.

A spectator can easily reproduce the last motion by means of the reverse replay. We chose a replay-duration of around 7 sec that turns out to be interesting to watch. We are assuming that it works for the span of the short-term memory, which is dependent on the complexity of the motion. Anyhow, we discovered that if the sequences are to long, they are more difficult to read and less interesting.

It is interesting for a spectator to observe that some motions "work" in reverse playback because they are physically plausible while others are not.

While working with this set-up, we were reminded of one of the chapters in an early version (1994) of the Ballet Frankfurt CD-Rom Improvisation Technologies. The chapter ‘iteration’ deals with the awareness of what and where a movement or position was and how it can be revisited.

 

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Related Experiments

 

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Setup

 

Hardware:

  • Graphics PC with Video Capture Card
  • Projector
  • Polhemus tracking system: 1 Sensor
  • Video Camera



Configuration:

  • The Video Camera is facing the dancer and transmits a live video image to the graphics computer. The graphics computer displays this image on the projection screen. The image is overlaid by a round spot, which shows a time reversed video playback of the last 3 seconds. The computer continuously stores the incoming video frames in a frame queue. A looped internal timer selects one out of these stored images in a reversed order and displays it within the spot.
  • The Sensor controls the position of the spot on screen. In the recording we attached the sensor to the dancer's left hand.

 


Technical Setup

Spatial Setup

Technical Screenshot

Screenshot
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