Dragan Ahmetovic

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In this paper we propose a computer vision-based technique that mines existing spatial image databases for discovery of zebra crosswalks in urban settings. Knowing the location of crosswalks is critical for a blind person planning a trip that includes street crossing. By augmenting existing spatial databases (such as Google Maps or OpenStreetMap) with this(More)
Independent mobility in unfamiliar environments is a significant challenge for people with severe vision impairment. Among other problems, one specific issue concerns the identification of those road signs that can be recognized by sight only. In this paper we present <i>ZebraLocalizer</i>, an application for mobile devices that identifies zebra crossings(More)
Turn-by-turn navigation is a useful paradigm for assisting people with visual impairments during mobility as it reduces the cognitive load of having to simultaneously sense, localize and plan. To realize such a system, it is necessary to be able to automatically localize the user with sufficient accuracy, provide timely and efficient instructions and have(More)
Autonomous mobility is a challenge for visually impaired people. In the last years, a number of solutions have been proposed in the scientific literature to support visually impaired people during road crossing. In our previous work we presented ZebraLocalizer a mobile application that detects zebra crossings and guides the user to safely cross. In this(More)
NavCog is a novel smartphone navigation system for people with visual impairments or blindness, capable of assisting the users during autonomous mobility in complex and unfamiliar indoor/outdoor environments. The accurate localization achieved by NavCog is used for precise turn-by-turn way-finding assistance as the first step, but the ultimate goal is to(More)
In the field of assistive technology, large scale user studies are hindered by the fact that potential participants are geographically sparse and longitudinal studies are often time consuming. In this contribution, we rely on remote usage data to perform large scale and long duration behavior analysis on users of iMove, a mobile app that supports the(More)
For visually impaired users one of the major challenges is unassisted orientation and way-finding, especially in unexplored and potentially dangerous environments. The following work analyzes the issues stemmed from this problem and summarizes the merits and flaws of solutions available in literature. Afterwards, the research methodology is briefly(More)
It is well known that mathematics presents a number of hindrances to visually impaired students. In case of function graphs, for example, several assistive solutions have been proposed to enhance their accessibility. Unfortunately, both hardware tools (e.g., tactile paper) and existing software applications cannot guarantee, at the same time, a clear(More)