Scientists develop "electronic eye" for the blind 

An effective navigation system would improve the mobility of millions of
blind people all over the world. A new "eye" developed by scientists in Japan
will allow blind people to cross busy roads in total safety for the first
time. The "electronic eye", which would be mounted on a pair of glasses, will
be capable of detecting the existence and location of a pedestrian crossing,
and at the same time measure the width of the road to the nearest step and
detect the colour of the traffic lights. This research appears today (19th
November) in the journal Measurement Science and Technology published by the
Institute of Physics.  

Tadayoshi Shioyama and Mohammad Uddin, from the Kyoto Institute of Technology
in Japan, have developed a system that is able to detect the existence of a
pedestrian crossing in front of a blind person using a single camera. When
combined with two other techniques the authors have produced, for measuring
the width of the road and the colour of traffic lights, a single camera can
now give the blind all the information they need to cross a road in safety. 

Although some crossings make a sound when it is safe to cross, many do not.
This issue has been tackled in the past. Adaptations have, for example, been
made to the most common travel aid used by blind people, the white cane.
There are some canes with added functions which use lasers or ultrasound to
detect more distant obstacles. One such is the Talking Cane from Sten Lefving
Optical Sensors in Sweden. But this technology cant give information about
the location of a crossing, width of the road or the colour of the traffic
lights. 

Professor Shioyama said: "The camera would be mounted at eye level, and be
connected to a tiny computer. It will relay information using a voice speech
system and give vocal commands and information through a small speaker placed
near the ear".  

The device developed at Kyoto is the final product of a research programme
that aimed to give blind people all the navigation information they needed to
cross a road from a single small camera. Last year, the authors announced
that they had designed a computer-aided camera that could measure the length
of a crossing to within one step length - and simultaneously detect the
colour of the traffic lights. Crucially, it couldnt tell you where the
crossing actually was until now. 

Using images from a single camera, the device has a simple structure: unlike
sophisticated stereo camera systems it does not need camera calibration. (The
information is obtained using a 'camera coordinate system,' so separate
images do not need to be taken to calibrate the device). The length of a
pedestrian crossing is measured by projective geometry: the camera makes an
image of the white lines painted on the road, and then the actual distances
are determined using the properties of geometric shapes as seen in the image.
Experiments carried out by Shioyama and his colleagues showed that the
crossing length could be measured to within an error of only 5 per cent of
the full length - which is less than one step. 

Shioyama and Uddin have now made a breakthrough in detecting the location of
crossings in the first place and added this to their original camera. To do
this they used a calculation called the "projective invariant" which takes
the distance between the white lines (called the band width) and a set of
linear points on the edges of the white lines, to give an accurate way of
detecting what is or isnt a crossing in a given image.  

They used this technique to analyse 196 images and it proved successful in
detecting whether there was a crossing present in 194 of them. In the two
images where the system made a mistake, it said there wasnt a crossing where
there really was one. 

Katherine Phipps, Accessible Environments spokesperson at the Royal National
Institute of the Blind said: "Mobility is a serious issue for blind and
partially sighted people and new tools like this that may help people with
sight problems get around safely are always welcome". 

To see the full press release, go to:
http://physics.iop.org/IOP/Press/prlist.html


Contributed by Jamie Prioli
