When seeing is not believing

THIS IS perhaps the closest that a live performance could come to Star Trek fused with The Matrix. The four identically dressed dancers in Vivisector are used as a "blank canvas" for the piece, which is situated somewhere between video installation, sound environment and dance performance. They appear to vanish and then reappear in another place at lightning speed. They morph from one form to another, dematerialising and mutating, as the boundaries between what is real and what is not are blurred.

Computer and video images projected on to the performers' bodies create an interplay between them and their virtual counterparts. The fit is so exact that the projected image "becomes part of the body" - it is difficult to distinguish between a live and a fake performer.

However, Klaus Obermaier, the Austrian multimedia artist and technical wizard who developed the work, is keen to stress that it is not "overruled by technology". Along with the choreographer and dancer Chris Haring, Obermaier premiered Vivisector at the South Bank in early 2002, to the accompaniment of the trance music that he had composed. "The human body has been used in dance before as a screen for slide or video projections," he says. "But here, I project the moving image of the dancer again on to his body, so I can manipulate the appearance, and control when the performer appears. I break the linearity of movement that we are familiar with in the virtual characters of video games."

Both Obermaier and Haring are pioneers in the field of integrating dance with digital technology. This is their second collaboration, following D.A.V.E., in 2002, a solo performance in which this technological trick of moving body-projections was first demonstrated.

Obermaier originally studied music (classical guitar) and painting. "It was always my intention to choose between the two at some point, but the possibilities offered by computers of combining visual art and electronic music was a way of bringing my two sides together and building something new - although it was a surprise to me when I discovered that my work was groundbreaking."

Haring, who also dances in the piece, has worked with the British company DV8, and Austrian companies such as Willi Dorner, Pilottant and Tanz Hotel. Obermaier's interactive media installations have been shown in galleries in Europe and New York, and as well as creating his own hypnotic urban rhythms, he has played with Ensemble Modern and composed for the Kronos Quartet, the Art Ensemble of Chicago, and the Deutsche Kammerphilharmonie.

Vivisector has a subtitle - Intervention in the Sweating Body - to remind the audience "that what it sees is not like in a cinema", Obermaier explains. "There is a sweating figure underneath the projections."

Queen Elizabeth Hall, London SE1 (020-7960 4242), 21 and 22 February