Stereo sight
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A device that aims to help blind people sense their environment has been developed by researchers as part of the three-year EU-funded CASBliP project.
The system uses stereo images to produce information on the behaviour of moving objects, which is then relayed to a blind person in the form of a sound map.
Project co-ordinator, Guillermo Peris-Fajarnés from Universidad Politécnica de Valencia, explained: 'Part of our brain associates sound with spatial awareness. Research undertaken by Laguna University suggests that we soon forget hearing these sounds and instead build up a three-dimensional image of our environment. This can be used to convey details of an object's size and distance to aid in the mobility of a blind person.'
The CASBliP (Cognitive Aid System for Blind People) project brings together seven European organisations with expertise in the fields of positioning systems, artificial vision, audio and visual interface, object detection and cognitive 3D models.
The artificial-vision component of CASBliP is based on research undertaken at Bristol University that focused on the development of stereo cameras that capture, analyse and process in-depth images of the surrounding environment. The captured scenes are converted into images that feature simplified information such as contrast and depth.
Peris-Fajarnés said: 'We started a search for experts in artificial vision. We knew that Bristol University had done work a few years ago relating to people with partially sighted vision. Combining this expertise with an infrared laser designed by Siemens, we were able to develop a three-dimensional image-processing system that could provide real-time information on distances between objects.'
Siemens' laser was originally developed for the automotive industry for recognising pedestrians next to cars. The laser diode makes use of microflashes to measure 64 distance points within a viewing angle of 60° at a distance of five metres on a horizontal plane. Gaps in elapsed time are then converted into a distance profile of the environment, which is relayed using audible signals.
The shorter the distance of the object, the higher the pitch of sound. Due to the different angles from which the infrared light is reflected, there is also an audible left-to-right effect. This area is being developed by Laguna University in Spain, which has created a system that provides spatial awareness and 'externalises' the sound so that the user perceives it is coming directly from the surface of objects.
The various technologies have integrated into two prototype models. The first is a portable system using special sunglasses and headphones. The second is a mobility system that enables a blind user to detect moving objects within a range of around 15m. Both models are currently undergoing trials.
Peris-Fajarnés said: 'At the moment, these prototypes are probably the highest technology available for the completely blind. However, they are only prototypes and there are always improvements we can make.'
Peris-Fajarnés added that, with the right backing, a device could be on the market within six months.
Ellie Zolfagharifard
Readers' comments (1)
brian - Stereo sight | 13 Jul 2009 5:35 pm
As they say nothing new under the sun! Similar research into using a sound map as a way of passing visual information to a subject was done at Manchester University back in the 80's.
The technique of data reduction and the use of a sound map certainly worked with subjects being able to identify human shapes, tea cups etc. However the technique is limited by the resolution and serial nature of the sound field. The human visual system has 6 million colour sensitive cones and 120 million rod cells (read pixels), with 400,000 nerve fibres leading from the eye to the brain - parallel processing with attitude!
Compare this to the ear with 3,500 inner and 20,000 outer hair cells and 28,00 nerve fibres - still impressive but just doesn’t have the same data capacity. Is the user going to want to handover some of the hearing bandwidth to get low resolution visual information? I suspect not. The system might well find better use for those with partial sight by mapping the processed images/information directly to working parts of the visual system such as in Age related Macular Degeneration(AMD). Or perhaps a spoken warning to let the user know they are about to step off a kerb – Whichever way an interesting project!
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