3D scanning is a technology which is finally coming into its own: Its potential has been obvious since the earliest days of 3D computer graphics, but it is only in the last few years that the state of the art has really started to live up to the possibilities.

One of the great challenges in 3D graphics has always been the creation of models which look as much as possible like either the real-world things they are supposed to represent, or the vision of the artist behind them. 3D scanning allows us to create models directly from real objects, people and so on, matching their geometry, texture and colour very closely.

With the help of 3D scanning, film-makers can make use of computer graphics representations of actors which are so convincing that they can be integrated seamlessly with live action – a technique used to good effect in the Matrix sequels, and something which would never have been possible a few years ago.

The technology is also a boon to special effects companies interested in creating less naturalistic characters and objects to use in films, and to artists interested in using computers in their creative endeavours. In the past, 3D models needed to be made by people who had mastered software packages like Maya or 3D Studio Max. These are often complex and not always intuitive to use - besides which many sculptors and modellers feel much more comfortable using their hands or physical tools to shape their creations, feeling that this allows for a more direct connection between sculptor and sculpted. These factors have often led to a gulf between computer modellers and more traditional sculptors, which can now be readily bridged.

It is not only in the fields of special effects, art and animation that 3D scanning opens up many new and intriguing opportunities. Museums are now able to display 3D models of ancient artifacts, scanned at near-microscopic resolution (to around a tenth of a millimetre), for visitors to view from any angle in greater detail than would otherwise be possible, and manipulate at will without having to fear for the safety of the pieces. The same approach is invaluable for archaeologists, who can now examine works all over the world, which they might otherwise never have gained access to.

Another area where 3D scanning opens up exciting vistas of possibilities is in industrial design. Computer Aided Design (CAD) has been a staple of many industries for many years, allowing people to create prototypes in computers without having to make them for real, to test out how they would look or operate. 3D scanning makes it possible to reverse the process, and make computer models out of things which existed already.

One especially intriguing possibility is to combine 3D scanning with 3D printing, another technology which is just starting to fulfil its promise. In 3D printing, objects are built up layer by layer from a computer model. The process typically involves condensing plastic or metal from a vapour with the help of a laser. In principle it is now possible to scan an object into a computer and "print" near-exact copies made out of any of several materials. Right now the technologies are too expensive to be viable for either mass-production or home use, but they have already been used to create small runs of aeroplane parts, among other things. CNC milling - Computer Numerical Controlled milling - can achieve many of the same things.

Several variations on 3D scanning have been used in medicine for some years. These include 3D ultrasound scans, CT scans and MRI scans; in all cases, having the data available in 3D can bring out features and perspectives which might otherwise have been missed. General-purpose 3D optical scanning can also be used to enable doctors and students to study body parts in great detail without necessarily having them to hand.

There are several approaches to 3D scanning - not to mention various other ways of getting real objects into computers, such as photogrammetry, which works along similar lines to stereo vision in humans. The approach used in the Matrix sequels was originally developed by the Canadian government; the worldwide licence for this is held by Arius3D and the UK licence is held by Kestrel3D, a Scottish-based company formed from the merger of what used to be the multimedia wing of the National Museums of Scotland with Arius3D Europe. This technique uses red, green and blue lasers and a digital camera to record the colour and position in space of millions of points on the surface of an object, to create a 'point cloud' from which a 3D mesh of polygons is created. The mesh can then be reduced to an appropriate level of complexity by software and human operators.

At the moment 3D scanning equipment is too expensive to be owned by most small businesses or private individuals, although companies like Kestrel3D are all about allowing third parties to use their state-of-the-art facilities at a price. However, a couple of new approaches to the problem promise to bring cheap 3D scanning to desktops within a few years – albeit nothing as sophisticated as present-day professional systems. Australia's Commonwealth Scientific & Industrial Research organisation (CSIRO) has patented a system for adding 3D scanning capabilities to flatbed scanners, suitable for small objects; it says that this should add only a small premium to the cost of the machines. Another cheap system has been put together by a UK company called Spiral Scratch, which uses a grid of light and a turntable to generate models; it hopes to have this on the market within a couple of years.

While current technology is already hugely impressive, it is not yet able to produce a totally realistic, usable model of any object, with little or no human intervention. To achieve this, 3D scanners would need to be able to record not just the colour and texture of their target, but also other optical characteristics, such as their shininess and transparency. It may be a while yet before we see this, but with a little help from trained humans there is no limit to what can be achieved with what we have.

3D scanning, as a field, is blooming - but it is still young, and has plenty of room to grow yet. It will be interesting to see what the next few years hold.

Relevant sites:

  • http://www.kestrel3d.com
  • http://www.wohlersassociates.com/3D-Digitizing-and-Reverse-Engineering.html
  • http://www.asu.edu/cfa/art/people/faculty/collins/extreme3D.htm
  • http://www.csiro.au/3dscanner
  • http://www.tgs.com/index.htm?amapi7/index.htm~main

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