Dragan Ahmetovic

Dragan Ahmetovic
University of Milan | UNIMI · Department of Computer Science

About

64
Publications
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1,148
Citations

Publications

Publications (64)
Preprint
Full-text available
This contribution investigates how cross-platform development frameworks (CPDF) support the creation of mobile applications that are accessible to people with visual impairments through screen readers. We first systematically analyze screen-reader APIs available in native iOS and Android, and we examine whether and at what level the same functional...
Article
Navigation assistive technologies are designed to support people with visual impairments during mobility. In particular, turn-by-turn navigation is commonly used to provide walk and turn instructions, without requiring any prior knowledge about the traversed environment. To ensure safe and reliable guidance, many research efforts focus on improving...
Conference Paper
Mobile devices are accessible to people with visual impairments and hence they are convenient platforms to support assistive technologies. Indeed, in the last years many scientific contributions proposed assistive applications for mobile devices. However, few of these solutions were eventually delivered to end-users, depriving people with disabilit...
Conference Paper
People with visual impairments or blindness (VIB) encounter difficulties in exploring graphical representations that are widely used for the study of STEM subjects. In particular, graphs are used to represent many different scientific notations: flowcharts, automata, cognitive maps, and more. Among these, structural chemical formulae are characteri...
Conference Paper
Independent mobility is one of the main challenges for blind or visually impaired (BVI) people. In particular, BVI people often need to identify and avoid nearby obstacles, for example a bicycle parked on the sidewalk. This is generally achieved with a combination of residual vision, hearing and haptic sensing using the white cane. However, in many...
Conference Paper
We present WordMelodies, an inclusive, cross platform, mobile app that supports children with visual impairments in the acquisition of basic literacy skills through 8 different exercises. WordMelodies has been designed and evaluated by three domain experts in assistive technologies and education for children with visual impairments. After three des...
Article
Independent navigation is challenging for blind people, particularly in unfamiliar environments. Navigation assistive technologies try to provide additional support by guiding users or increasing their knowledge of the surroundings, but accurate solutions are still not widely available. Based on this limitation and on the fact that spatial knowledg...
Article
Full-text available
NavCog3 is a smartphone turn-by-turn navigation assistant system we developed specifically designed to enable independent navigation for people with visual impairments. Using off-the-shelf Bluetooth beacons installed in the surrounding environment and a commodity smartphone carried by the user, NavCog3 achieves unparalleled localization accuracy in...
Conference Paper
Full-text available
Il Laboratorio per la Ricerca e la Sperimentazione di Nuove Tecnologie Assistive per le STEM "S. Polin" fa parte del Dipartimento di Matematica “G.Peano” dell’Università di Torino e opera nell'ambito della ricerca e della sperimentazione di nuove tecnologie assistive per lo studio delle STEM (Science, Technology, Engineering and Mathematics). Prend...
Chapter
Scientific documents are a very specialised type of literature not only in terms of their topics and intended audience, but also in terms of their content and how it is presented. They generally use highly topical vernacular, mathematical formulas, diagrams, data visualisations, etc. While any single one of these features on its own poses a conside...
Conference Paper
We present AudioFunctions.web, a web app that uses sonification, earcons and speech synthesis to enable blind people to explore mathematical function graphs. The system is designed for personalized access through different interfaces (touchscreen, keyboard, touchpad and mouse) on both mobile and traditional devices, in order to better adapt to diff...
Conference Paper
AudioFunctions.web is a web-based system that enables blind people to explore mathematical function graphs. It uses sonification, earcons and speech synthesis to convey the overall shape of a function graph, its key points of interest, and accurate quantitative information at any given point. The system can be directly linked from digital documents...
Conference Paper
Full-text available
People with visual impairments often have to rely on the assistance of sighted guides in airports, which prevents them from having an independent travel experience. In order to learn about their perspectives on current airport accessibility, we conducted two focus groups that discussed their needs and experiences in-depth, as well as the potential...
Conference Paper
Full-text available
Independent navigation in unfamiliar and complex environments is a major challenge for blind people. This challenge motivates a multi-disciplinary effort in the CHI community aimed at developing assistive technologies to support the orientation and mobility of blind people, including related disciplines such as accessible computing, cognitive scien...
Article
Continuous, accurate, and real-time smartphone-based localization is a promising technology for supporting independent mobility of people with visual impairments. However, despite extensive research on indoor localization techniques, localization technologies are still not ready for deployment in large and complex environments such as shopping mall...
Conference Paper
Full-text available
Museums are gradually becoming more accessible to blind people, who have shown interest in visiting museums and in appreciating visual art. Yet, their ability to visit museums is still dependent on the assistance they get from their family and friends or from the museum personnel. Based on this observation and on prior research, we developed a solu...
Conference Paper
Full-text available
Navigation assistive technologies have been designed to support individuals with visual impairments during independent mobility by providing sensory augmentation and contextual awareness of their surroundings. Such information is habitually provided through predefned audio-haptic interaction paradigms. However, individual capabilities, preferences...
Conference Paper
Full-text available
Cross-platform developing techniques have been attracting lot of attention in the last years, especially in the field of mobile application, because they enable the developers to code apps in a same programming language for different platforms (e.g. iOS and Android). One well-known framework for cross-platform development is React Native that prese...
Conference Paper
Full-text available
People with visual impairments (PVI) have shown interest in visiting museums and enjoying visual art. Based on this knowledge, some museums provide tactile reproductions of artworks, specialized tours for PVI, or enable them to schedule accessible visits. However, the ability of PVI to visit museums is still dependent on the assistance they get fro...
Conference Paper
Full-text available
Indoor navigation is an important service, currently investigated both in industry and academia. While the main focus of research is the computation of users' position, the additional challenge of conveying guidance instructions arises when the target user is blind or visually impaired (BVI). This contribution presents our ongoing research aimed at...
Poster
Full-text available
Accessing mathematical formulae within digital documents is challenging for blind people. In particular, document formats designed for printing, such as PDF, structure math content for visual access only. While accessibility features exist to present PDF content non-visually, formulae support is limited to providing replacement text that can be rea...
Conference Paper
Full-text available
Navigation assistive technologies aim to improve the mobility of blind or visually impaired people. In particular, turn-by-turn navigation assistants provide sequential instructions to enable autonomous guidance towards a destination. A problem frequently addressed in the literature is to obtain accurate position and orientation of the user during...
Conference Paper
Full-text available
Recent techniques for indoor localization are now able to support practical, accurate turn-by-turn navigation for peo­ple with visual impairments (PVI). Understanding user be­havior as it relates to situational contexts can be used to improve the ability of the interface to adapt to problem­atic scenarios, and consequently reduce navigation errors....
Article
Indoor navigation systems can make unfamiliar buildings more accessible for people with vision impairments, but their adoption is hampered by the effort of installing infrastructure and maintaining it over time. Most solutions in this space require augmenting the environment with add-ons, such as Bluetooth beacons. Installing and calibrating such i...
Conference Paper
Full-text available
Evaluating the impact of expertise and route knowledge on task performance can guide the design of intelligent and adaptive navigation interfaces. Expertise has been relatively unexplored in the context of assistive indoor navigation interfaces for blind people. To quantify the complex relationship between the user's walking patterns, route learnin...
Conference Paper
Full-text available
Continuous and accurate smartphone-based localization is a promising technology for supporting independent mobility of people with visual impairments. However, despite extensive research on indoor localization techniques, they are still not ready for deployment in large and complex environments, like shopping malls and hospitals, where navigation a...
Conference Paper
Full-text available
Head movements are an integral part of human nonver-bal communication. As such, the ability to detect various types of head gestures from video is important for robotic systems that need to interact with people or for assistive technologies that may need to detect conversational gestures to aid communication. To this end, we propose a novel Multi-S...
Article
Full-text available
Assistive applications for orientation and mobility promote independence for people with visual impairment (PVI). While typical design and evaluation of such applications involves small-sample iterative studies, we analyze large-scale longitudinal data from a geographically diverse population. Our publicly released dataset from iMove, a mobile app...
Conference Paper
Full-text available
When preparing to visit new locations, sighted people of­ten look at maps to build an a priori mental representation of the environment as a sequence of step-by-step ac­tions and points of interest (POIs), e.g., turn right after the coffee shop. Based on this observation, we would like to understand if building the same type of sequential rep­resen...
Conference Paper
Full-text available
Providing navigation assistance to people with visual impairments often requires augmenting the environment with after-market tech­nology. However, installing navigation infrastructure in large envi­ronments requires a critical mass of trained personnel. Recruiting, training and managing participants for such a task is difficult. LuzDeploy is a com...
Conference Paper
Full-text available
Methods that provide accurate navigation assistance to people with visual impairments often rely on instrumenting the environment with specialized hardware infrastructure. In particular, approaches that use sensor networks of Bluetooth Low Energy (BLE) beacons have been shown to achieve precise localization and accurate guidance while the structura...
Article
Full-text available
For blind travelers, finding crosswalks and remaining within their borders while traversing them is a crucial part of any trip involving street crossings. While standard Orientation 8 Mobility (O8M) techniques allow blind travelers to safely negotiate street crossings, additional information about crosswalks and other important features at intersec...
Conference Paper
Full-text available
For children with visual impairments, learning mathematics entails significant difficulties. This is partially due to the fact that both traditional and digital didactic tools for teaching mathematics to children often integrate visual elements into explanations and exercises in order to improve children's engagement and comprehension. These visual...
Conference Paper
Full-text available
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 t...
Conference Paper
Full-text available
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 a...
Conference Paper
Many traffic lights are still not equipped with acoustic signals. It is possible to recognize the traffic light color from a mobile device, but this requires a technique that is stable under different illumination conditions. This contribution presents TL-recognizer, an application that recognizes traffic lights from a mobile device camera. The pro...
Article
Full-text available
Independent mobility is a challenge for people with visual impairment or blindness. Groundbreaking innovation comes from mobile devices (e.g., smartphones) that are convenient platforms to provide assistive technologies in the form of mobile applications. This paper presents ZebraRecognizer, a software module that recognizes zebra crossings and tha...
Conference Paper
Full-text available
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...
Article
Full-text available
Independent mobility involves a number of challenges for people with visual impairment or blindness. In particular, in many countries the majority of traffic lights are still not equipped with acoustic signals. Recognizing traffic lights through the analysis of images acquired by a mobile device camera is a viable solution already experimented in s...
Conference Paper
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) w...
Article
Full-text available
In the last years several solutions were proposed to support people with visual impairments or blindness during road crossing. These solutions focus on computer vision techniques for recognizing pedestrian crosswalks and computing their relative position from the user. Instead, this contribution addresses a different problem; the design of an audit...
Conference Paper
Full-text available
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 Zebra Localizer a mobile application that detects zebra crossings and guides the user to safely cross. I...
Conference Paper
Tablet computers are becoming a common tool to support learning since primary school. Indeed, many didactic applications are already available on online stores. Most of these applications engage the child by immersing the educational purpose of the software within an entertaining environment, often in the form of a game with sophisticated graphic a...
Conference Paper
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 cle...
Conference Paper
Many solutions proposed in the literature to enforce privacy in presence of location information use, implicitly or explicitly, spatial granularities. However, most of the contributions do not describe the formal and computational properties of this tool in details. In this paper we propose three families of spatial granularities, specifically desi...
Conference Paper
Full-text available
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...
Conference Paper
For users with sensory or mobility impairments the evolution of mobile devices introduces new accessibility issues. For instance, touch screens, lacking tactile cues, are hard to use by blind users without additional feedback. These problems are being mitigated through new interaction paradigms, such as screen readers: software that describe the cu...
Conference Paper
Full-text available
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 ZebraLocalizer, an application for mobile devices that identifies zebra crossings...

Projects

Projects (3)
Project
The project originates from the necessity of the deployment and use of new technologies for access to higher scientific education by young people with disabilities (both sensorial and motor). The project, developed in its technological aspects in the Department of Mathematics "G. Peano", University of Turin, is in collaboration with the Office of Disabled Students and the Department of Philosophy and Educational Sciences.