Stereo sight

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.