Touch is real-time graphics software geared to video artists and VJs. Touch is at the centre of all these artworks – see diagram 1 – and controls a variety of functions including input from video cameras and MIDI sensors; output to video projectors, lighting equipment and motors; and communications with other programs. Between input and output, Touch accomplishes lightning fast 3D graphics, including 3D modeling, video analysis of form and movement, control of arrays of sensor input and output of dynamic video art. Touch is particularly suited to interactive art for this reason – see various other examples at www.derivativeinc.com

The key Touch functions we are using in these artworks are called a 3D Texture Map, a Time Map and a Time Machine CHOP – see diagram 2. Successive frames of video are stack one on top of the other to form a cube of video frames. This cube is called a 3D texture map (a recently developed component of the NVidia graphics cards). The 3D texture map can then be manipulated in interesting ways: it can be digitally sliced, carved or warped. When simply viewed from the top of the cube the video frame is composed of pixels which are taken from as far back in time as the memory card allows. A Time map is used to define how far the time machine will reach back into time to grab a particular pixel: a black pixel means grab the pixel in the texture map on top (the current frame), while white grabs the pixel in frame n seconds ago. Therefore, if the time map is an even gradient from dark to light, then the output image is evenly “time stretched” from current to past frames.