Feb. 6, 2007 — An imaging technology originally used to find bumps and flaws in
industrial surfaces is now being turned on the tiny details of the human face to produce three-dimensional pictures.
Such detailed maps of a person's features could be used for security purposes in places like airports and banks, but it could also lead to better imaging and diagnosing of skin trauma such as
burns.
The images can be combined with software that adjusts for light or other
conditions if security officials need to compare a photo with one
taken previously with another camera or under different
conditions.
"You can create how that person would have looked if seen under
different viewing conditions and then match it against a database of
suspects...or you may use computer graphics to see how the person looks
with glasses or moustache," said Maria Petrou, team
leader on the project at Imperial College London.
The technique, called photometric stereo, uses a fixed digital camera
and at least three lights placed around it to illuminate the face from
different angles.
The lights are synchronized to flash
very quickly in succession, in a few hundredths of a second, so
the person being photographed only perceives one flash. But the
computer picks up digital data for all lighting angles.
A program written by Petrou and her colleagues analyzes the shadows
and highlights, and then combines them
into one three-dimensional image.
