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Paul Beckmann; Behavioural Evaluation of the Digital Sign System (DSS). Journal of Vision 2007;7(15):35. doi: 10.1167/7.15.35.
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Localization within a building is a difficult task for those with impaired vision. Outdoor solutions based on GPS technology are gaining a foothold but GPS signals do not penetrate buildings. While some solutions such as Talking Lights and Talking Signs have been introduced, these require expensive installation and maintenance and generally provide a fixed message to the wayfarer. We have evaluated a different approach to localization within a building that we call the Digital Sign System (DSS). A critical component of this system is a small hand-held camera (“Magic Flashlight”) and associated computer-vision software that allows the user to detect, localize, and read (with synthetic speech) inexpensive credit-card sized signs within a hallway environment in real time. In addition to information directly associated with a sign, a user can also request information about building attributes in the immediate and extended vicinity of the sign from a database system called the Building Navigator.
Three groups of subjects participated in the study: those who were visually-impaired but used vision to avoid walls while walking in buildings (“low vision”), those who did not use vision while walking in buildings (“blind”), and normally sighted but blindfolded subjects. In the first study, we placed signs one at a time on walls within a simple environment. We compared the time for the subjects to find a sign using their well-practiced common mobility skills with and without the DSS Magic Flashlight. In the second study we measured how well subjects navigated from one location to another in a building layout, comparing performance using typical tactile signage and the Digital Sign System. In the first study, the mean times for visually-impaired subjects to localize a sign with the Magic Flashlight compared with direct physical localization were 25% shorter even though the subjects had no previous training with the device.
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