BBC Correspondent Sue Nelson: Piccadilly's digital facelift for the millennium

Technology is changing the face of one of London's most famous landmarks.

From Wednesday night, the neon signs at Piccadilly Circus will be joined by the site's first digital billboard - and it promises to outshine its more traditional neon rivals.

Moving images are delivered by six video cards mounted into a single PC

It will have moving images instead of the usual static screen. It will also be able to change with the weather as it detects daylight, rain, snow and changes in temperature and matches its display to mirror the conditions.

Managing Director of the design house Sedley Place Mick Nash said: "It blends art, science and commerce. We have called it Street Vision because it is a whole new way of talking to the public. It is not TV and not a poster, but a new type of media which cuts across those two."

Mick Nash: "It is a whole new way of talking to the public"

This is the first display of its kind. It took four years to design and replaces its neon counterpart after almost 50 years' service.

Five hundred pieces of steel went into its construction, with 36 glass panels - each more than one metre square - making up the screen.

New technology, familiar messages

Behind these panels, inside the air conditioned billboard, hang thirty six LCD video projectors.

These produce an all-singing, all-dancing image which is actually focused three metres in front of the screen so that it looks best from the ground.

The screen is also tilted at an angle of six degrees to help passers by on the pavement get a better look.

The computer-controlled images are delivered by six video cards mounted into a single PC. Each drive is loaded with one sixth the image at full resolution so that the overall resolution of the sign is as high as possible.

The effect is impressive - especially when compared to the, now, rather old fashioned neon signs surrounding it. Instead of static or flashing streams of light, the new digital image races across the screen, flips over, dissolves and bubbles.

It can even react to light, rain and wind speed thanks to sensors on the roof. So if it starts raining in central London, digital rain drops will also shower the sign.

Flipping its lid for the crowds

The combination of different technologies has also produced some innovation. A British company, Armfield Glass Ltd, devised a special glass connector to hold the panels together.

Now, for the first time, four panels of glass can be connected to the steel frame by one corner fixing rather than four and this could have other uses in future constructions.

Thankfully, the sign does not completely forget its roots. The billboard does an impressive imitation of neon strip lighting before converting into a giant bottle top and doing a high-tech spin in full view of Eros, the famous statue in the main square below.