Scanner paints a virtual crime scene

Forensics experts and road-accident investigators could soon revisit the scene of a crime without leaving their office, thanks to a 3D scanner that "paints" a virtual model of the area.

The hand-held scanner makes it possible to record a scene with millimetre accuracy and creates a computerised 3D model that can be navigated as if investigators were at the site, says Robert Valkenburg of Industrial Research in Auckland, New Zealand, which developed the technology.

The device consists of a laser scanner coupled to a digital camera. The scanner creates a 3D model of the scene, onto which images from the camera are overlaid. To ensure this is done accurately, the device needs to keep a constant track of its position. It achieves this using a sort of local GPS system, in which a number of "satellites" placed on tripods around the scene emit laser pulses. These are detected by sensors fitted to the scanner, allowing the device to calculate its position by triangulation. At least 20 of these laser beacons are needed, says Valkenburg - the more beacons, the greater the accuracy.

As the device is swiped in front of objects, walls or other surfaces, they automatically appear on screen "like brushstrokes", says Valkenburg, as part of the emerging 3D model. A number of other scanning technologies are available, but none can capture scenes with such photorealism, he adds.

The device could also be used to scan heritage sites, historical artefacts and movie and video game props, Valkenburg says.

via Scanner paints a virtual crime scene - tech - 11 January 2009 - New Scientist.