MEMORY RELEASE
Technology
(from process notes and public talk transcript)
The motion capture system we worked with has been developed by Hypervision and is based at essexdance (U.K). It is conventionally used in conjunction with Filmbox, a software for the conversion of raw movement data into virtual bodies in virtual environments.
There were four stages in the final data translation to command inititation process:
A. The motion capture rig – the system outputs a stream of the position of every sensor on the body in space 30 times a second.
B. Chris Fayer’s programming: allows us to compare the positions of the sensors- by selecting sets of sensors and then applying a variety of algorhythms to those selected sensors which results in composite output values. These algorhythms can be as simple as the following: the output value as the distance between two sensors or for instance the angle formed by a line of three sensors, or the velocity at which a sensor is moving. An xml was developed which was based on protocol for communication between this programme and Joshua Portways’ software. Chris’ programming language was visual basic.
C. Joshua Portay’s software: The numbers produced by the second stage can be applied to any atrribute of a video mixer (an open GL based 3D video mixing system, running on Os X) the velocity of a sensor could be mapped to the volume of a sound channel – or the proximity of a sensor mapped to the opacity of a video. The video software created can deal with two or three video channels simultaneously at full frame rate and ten sound channels in realtime. The latency of the system is currenlty about a 15th – 20th of a second, this will be one of the areas of development on the software. This software allows for changing position, opacity and colour of a video stream in realtime. It was programmed in Objective C and Cocoa.
D. The final stage was linking all data regarding the movement of the body to the live projection, via the programming tools and software.
Images explained
Images above show Camila (artistic collaborator), running through some choreographic tests to gain an understanding of what sensors and physical parameters to use in our mapping.
Next to her is a computer visualisation of incoming data from a moving body in suspension. The information is three dimensional; each of the white dots is a sensor on the body, the computer then takes that information and fills in the gaps – constructing a moving body.
The first image of the capture is taken a few moments before the second image of the live body.
How much can technology capture humanness? This system is incredibly accurate when we come to measuring positioning, orientation and velocity (mainly as acceleration). Yet it is unable to recognise actual quality of movement (how the body moves).