A Stereo-vision System for the Visually Impaired

Navigationis onesignificantbarrier to individualswith visual impairments.In responseto this barrier, we haveinvestigateda wearablestereo-visionsystemanda prototype systemhasbeendeveloped.Preliminaryinvestigationshave proven the viability of this device for navigationthrough simplehallwaystructures.Theprototypeis inexpensiveand consistsof two USBcameras, a “virtual touch” feedback systemanda wearablecomputer(inexpensivelaptopor embeddedplatform). Thefeedback systemis usedto relayvisualinformationvia tactile feedback throughtheuser’s fingers. Experimentationhasshownthefeasibilityof this approachandwesoonplanonexperimentingwith theplanned demographicsfor sucha device. Depthmeasur eswerecomputedusinga pixel-to-pixelcorrespondence methodmaking useof anepipolargeometryconstraint. Real-timeoperation was achievedby limiting the field of view to the effective field of view deemednecessaryfor navigation.Experimentationwasconductedwith a non-calibratedunit. Thedepth measur eswere crude, however calculationsrevealthat this inadequacymay be overcomeby making allowancesfor epipolaruncertaintyin thedepthfromstereoalgorithm.

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