EDINBURGH (Reuters) - The volcanic rock on which Edinburgh Castle perches became the screen for a 3-D digital light show on Sunday night, turning the western facade into a kaleidoscope of its past for the opening ceremony of the 2016 Edinburgh Festival, the world's biggest annual arts event.

The 350-million-year geology of the craggy Scottish capital was the inspiration for the show, bathing the rock in cascades of light to the delight of the 27,000-strong crowd watching live.

The animation focused on the idea of "deep time", a geological concept pioneered by James Hutton in Scotland in the 18th century, which helps to explain the earth's formation.

The show was created using architectural mapping technology and took almost 15 km of cable and 42 projectors to pull off. Set to an electronic soundtrack by Glasgow rock band Mogwai, it was billed by the organizers as "one of the largest and most unusual pieces of projection undertaken anywhere in the world".


Over three weeks in August, the Edinburgh International Festival takes place simultaneously with The Fringe, hosting more than 3,000 shows, and the Edinburgh Military Tattoo, which this year celebrates Queen Elizabeth's 90th birthday.

During the festival, street parades and performance art and music, children's theater and other events take place throughout the city, whose population doubles to around one million people for the duration.

(Reporting By Elisabeth O'Leary; Editing by Andrew Bolton)