Unlike other facial features used for biometrics, such as eyes or ears, noses are difficult to conceal and are not changed much by facial expression.
To investigate whether images of people’s noses could be used to recognise individuals, Dr Adrian Evans and Adrian Moorhouse, from the university’s Department of Electronic and Electrical Engineering, used a photographic system called PhotoFace to scan the 3D shape of volunteers’ noses and used computer software to analyse them according to six main nose shapes: Roman, Greek, Nubian, Hawk, Snub and Turn-up.
Instead of using the whole shape of the nose, the researchers used three characteristics in their analysis: the ridge profile, the nose tip and the nasion - the section between the eyes at the top of the nose.
They combined the curvature of the ridge with the ratios of the tip and nasion widths and ridge length. This combined ratio was then used to distinguish between a database of 36 people.
While the researchers used a relatively small sample, they found that nose scanning showed good potential for use as a biometric, with a good recognition rate and a faster rate of image processing than with conventional biometric techniques such as whole face recognition.
Dr Evans said: ’Noses are prominent facial features, and yet their use as a biometric has been largely unexplored. We wanted to find out how good they could be at recognising individuals from a database.’
While Evans admitted that irises are a powerful biometric, he said that they can be difficult to capture accurately and can easily be obscured by eyelids or glasses. Noses, he claimed, are much easier to photograph and are harder to conceal, so a system that recognises noses would work better with an uncooperative subject or for covert surveillance.
’We’ve only tried this on a small sample of people, but the technique certainly shows potential, perhaps to be used in combination with other identification techniques,’ he added.
Prof Melvyn Smith, who led the team at the University of the West of England (UWE) that developed the PhotoFace system, said: ’PhotoFace is an innovative 3D face data capture system developed as part of an EPSRC funded project involving UWE, Imperial College, the Home Office (Scientific Development Branch) and General Dynamics.’
It works by taking photos lit by a flash from several different angles so that four images are taken in very rapid succession of every point on the face, each under different controlled lighting conditions.
The technique is known as photometric stereo and UWE’s Machine Vision Laboratory is one of only three UK centres with expertise in this area. The software then works out the colour, surface orientation and depth of each point on the face by analysing the shading within each of the photos. The software analyses the shadows and works out coordinates for each point on the face
’The technique is able to achieve a level of detail that is beyond current competing technologies and can be extended to a myriad of other applications, ranging from industrial surface inspection to cosmetics,’ added Smith.
In the future, the researchers plan to build up a larger database of noses to test and refine the software to see if it can pick out individuals from a larger group of people, or distinguish between relatives from the same family.