Craig Robert's Report on how RTK-GPS was used in a Virtual Audio Reality System demonstration

Rattling chains and an eerie harpsichord din brought to life a sleepy Newtown cemetery as the new Lake Technology virtual audio reality system "Sonic Landscapes" demonstrated that there's life in those old stiffs yet.

SNAP and Lake Technology have recently combined to offer an audio experience that injects new life into the historic gravestones of Sydney's second oldest cemetery. Pre-recorded sound bytes describing the lives of the deceased are geo-located to scale with the actual positions of the corresponding memorials. A visitor, equipped with a Real Time Kinematic (RTK) GPS roving station (providing real-time centimetre accuracy), a digital compass for orientation and a pair of headphones, is immersed in a sonic landscape steeped in history. Using Lake Technology's patented 'surround sound' algorithms, a cacophony of noises emanate from all directions, beguiling the listener. A plane flies over head, yet there are no planes in the sky. A horse gallops by, but there is no horse. It becomes difficult to distinguish between what is real and what is part of the virtual audio world.

The sound bytes can be located anywhere on a virtual matrix simply by clicking and dragging into its corresponding "real" position provided by the GPS. Once all of the sound files are calibrated to the actual site, a moving listener triggers the sound byte simply by walking within a pre-defined range of the sound. As the listenerÕs head moves the digital compass points at different sounds, tricking the ear into believing that a sound really emanates from its virtual location. The sound bytes can betriggered again and again as the listener returns to already visited locations.

SNAP has utilised the advantages of RTK GPS for a radically different application, facilitating a virtual audio experience provided by Lake Technology, and transforming a quiet graveyard into a vibrant Sonic Landscape.