Understanding Echo Technical Notes
The installation creates a responsive environment using a combination of still digital imagery and projected video clips encoded as full-screen QuickTime. A video camera and infrared sensing software, which detects audience movement within three pre-programmed zones around the central projection area, control the installation. The software used was custom written in Java and C++ by Simon Yuill, controlling a fast hard disk and data projector. Connection between sensor and projection can be via Ethernet, Appletalk or Airport.
The projector is mounted directly above the pool). Via infrared sensing, software detects audience presence in any one of three zones marked by their corresponding distance from the centre of the installation: Distant, Intermediate and Intimate. The programme reacts to human presence by playing a corresponding projection, graded by emotional tone, which is displayed in the pool and linked to an image or class of images on the main screen. The anticipated movement of more than one audience member is compensated for by the logic of the programme.
Each video fragment is coded for audience distance and movement within a zone and is sequentially triggered by pre-programmed patterns of audience activity. The projected video fragments change without obvious repetition over a 40 minute cycle. The minimum required for Echo is a space approximately 10 metres square with low light conditions. 3 G4 Apple Macintoshes and two 1000 ansi lumens data projectors are required plus ethernet network hub and twin speakers and amp. Screens, cabling, infra-red lighting and detection systems are all supplied by the artist. A computer and projector are also available to the artist.