Electronics Weekly

Birkenhead start-up Spiral Scratch claims to have 3D scanning technology suitable for consumer applications. "We think ours is the only really cheap and the only really quick way of doing it," company managing director Dr John Wilson told EW. The scanner, like QinetiQ's 3D rangefinder (EW 17 March 2004), uses a projector and one camera, and avoids stereoscopic measurements.

Unlike QinetiQ's technique, which projects multiple thin beams, Spiral Scratch projects a grid pattern. "It can be sine wave or square wave. It must vary in a periodic way," said Wilson. The object to be scanned cannot be in the focal plane of the projector. "It must be in the area of demodulation [blurring] in front or behind the focus," said Wilson, in the region he calls the "linear far-field". 3D data is extracted from the camera image. "There are broadly two algorithms. One involves phase-stepping the pattern [sideways], the other needs no movement and uses correlation analysis. The maths isn't much different, but the second method gives lower resolution," said Wilson. Resolution using a system which would be suitable for mass production is around 1mm for a 100mm object. Mass market applications would include up-loading personal objects into computer games. "The human mind is easily fooled," said Wilson. "If an object has 1mm physical resolution, but is coloured to 0.1mm resolution, the whole thing looks like it is rendered to 0.1mm resolution. It is called 'low-poly high-texture'." Scanning is quick. "The processing load is extremely light. The longest scan we have done is three minutes," he said. The firm currently has an order book for specialist devices based on its technique for universities. "We will not be in the mass market for about two years," said Wilson.

Spiral Scratch is a spin-out from Unilever Research, from where the intellectual property was purchased, and was set up in 2002. "We have been going in anger for six months," said Wilson. Its business plan was developed with the help of Accenture and Unilever, and funding is from private investors and a DTI grant.

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