{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T01:05:52Z","timestamp":1779325552568,"version":"3.51.4"},"reference-count":36,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2012,12,17]],"date-time":"2012-12-17T00:00:00Z","timestamp":1355702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The aim of this article is focused on the design of an obstacle detection system for assisting visually impaired people. A dense disparity map is computed from the images of a stereo camera carried by the user. By using the dense disparity map, potential obstacles can be detected in 3D in indoor and outdoor scenarios. A ground plane estimation algorithm based on RANSAC plus filtering techniques allows the robust detection of the ground in every frame. A polar grid representation is proposed to account for the potential obstacles in the scene. The design is completed with acoustic feedback to assist visually impaired users while approaching obstacles. Beep sounds with different frequencies and repetitions inform the user about the presence of obstacles. Audio bone conducting technology is employed to play these sounds without interrupting the visually impaired user from hearing other important sounds from its local environment. A user study participated by four visually impaired volunteers supports the proposed system.<\/jats:p>","DOI":"10.3390\/s121217476","type":"journal-article","created":{"date-parts":[[2012,12,17]],"date-time":"2012-12-17T12:00:58Z","timestamp":1355745658000},"page":"17476-17496","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":143,"title":["Assisting the Visually Impaired: Obstacle Detection and Warning System by Acoustic Feedback"],"prefix":"10.3390","volume":"12","author":[{"given":"Alberto","family":"Rodr\u00edguez","sequence":"first","affiliation":[{"name":"Department of Electronics, University of Alcal\u00e1, Alcal\u00e1 de Henares, 28871 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J. Javier","family":"Yebes","sequence":"additional","affiliation":[{"name":"Department of Electronics, University of Alcal\u00e1, Alcal\u00e1 de Henares, 28871 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pablo","family":"Alcantarilla","sequence":"additional","affiliation":[{"name":"ISIT UMR 6284 CNRS, Universit\u00e9 d'Auvergne, 63001 Clermont-Ferrand, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Luis","family":"Bergasa","sequence":"additional","affiliation":[{"name":"Department of Electronics, University of Alcal\u00e1, Alcal\u00e1 de Henares, 28871 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Javier","family":"Almaz\u00e1n","sequence":"additional","affiliation":[{"name":"Department of Electronics, University of Alcal\u00e1, Alcal\u00e1 de Henares, 28871 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andr\u00e9s","family":"Cela","sequence":"additional","affiliation":[{"name":"Department of Automation and Industrial Control, National Polytechnic, EC170135 Quito, Ecuador"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2012,12,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Pradeep, V., Medioni, G., and Weiland, J (2010, January 13\u201318). 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