•The higher the elevation angle, the greater the horizontal localization error.•The upper limit of the elevation angle for acceptable localization accuracy was 65°.•Based on the limit, the effective ...distance of auditory guide signals was studied.
In Japan, auditory guide signals are commonly installed in public spaces to lead visually handicapped pedestrians to their destinations. The sound sources of the signals are usually installed at high places on walls. In other words, the sound sources have not only an azimuth angle but also an elevation angle when viewed from the users. In the present study, under the hypothesis that the horizontal localization error increases with increasing elevation angle of the sound source, a sound localization test allowing head movement was performed to clarify the upper limit of the elevation angle. The results of the test were consistent with the hypothesis and indicated that the upper limit of the elevation angle was 65° within the range of the signal used in the present study and the assumption that the correct discrimination of eight directions is sufficiently accurate in the application of auditory guide signals. Furthermore, the effective distance of auditory guide signals, that is, the closest distance that users can approach to the destination using the signals was studied on the basis of the results of the present study. As a result, it was found that the effective distance of auditory guide signals does not exceed 1 m, in other words, the signals work effectively in the range horizontally farther than 1 m, when the height of the sound source is less than 3 m.
Angle-closure glaucoma is a major cause of irreversible visual impairment and can be identified by measuring the anterior chamber angle (ACA) of the eye. The ACA can be viewed clearly through ...anterior segment optical coherence tomography (AS-OCT), but the imaging characteristics and the shapes and locations of major ocular structures can vary significantly among different AS-OCT modalities, thus complicating image analysis. To address this problem, we propose a data-driven approach for automatic AS-OCT structure segmentation, measurement, and screening. Our technique first estimates initial markers in the eye through label transfer from a hand-labeled exemplar data set, whose images are collected over different patients and AS-OCT modalities. These initial markers are then refined by using a graph-based smoothing method that is guided by AS-OCT structural information. These markers facilitate segmentation of major clinical structures, which are used to recover standard clinical parameters. These parameters can be used not only to support clinicians in making anatomical assessments, but also to serve as features for detecting anterior angle closure in automatic glaucoma screening algorithms. Experiments on Visante AS-OCT and Cirrus high-definition-OCT data sets demonstrate the effectiveness of our approach.
Waypoint navigation with a vibrotactile waist belt Erp, Jan B. F. Van; Veen, Hendrik A. H. C. Van; Jansen, Chris ...
ACM transactions on applied perception,
04/2005, Volume:
2, Issue:
2
Journal Article
Peer reviewed
Presenting waypoint navigation on a visual display is not suited for all situations. The present experiments investigate if it is feasible to present the navigation information on a tactile display. ...Important design issue of the display is how direction and distance information must be coded. Important usability issues are the resolution of the display and its usefulness in vibrating environments. In a pilot study with 12 pedestrians, different distance-coding schemes were compared. The schemes translated distance to vibration rhythm while the direction was translated into vibration location. The display consisted of eight tactors around the user's waist. The results show that mapping waypoint direction on the location of vibration is an effective coding scheme that requires no training, but that coding for distance does not improve performance compared to a control condition with no distance information. In Experiment 2, the usefulness of the tactile display was shown in two case studies with a helicopter and a fast boat.
It is difficult for visually handicapped people to recognize spaces and their position in circular structures. They often have accidents or lose their way in such situations. In my previous studies, ...I found that they not only lost their way but also were not safe around circular structures. Therefore, I surveyed the spatial cognition of visually handicapped people walking outside circular structures. In this study, in order to clarify the spatial cognition of the visually handicapped and the characteristics of their search behavior, experiments were carried out by producing 4 kinds of model structures of circular plan. I chose 12 totally blind people ages 22 to 39 and 12 sleep mask wearers ages 18 to 24. I will call the sleep mask wearers s.m.w. The results are as follows. 1. Walking speed of both the visually handicapped and the s.m.w. were 0.45m/s regardless of the radius when walking 1 lap, and this speed were 1.3 times of 1/4 laps. The rate of lap difference of the visually handicapped were 20-30 % and that of the s.m.w. were 30-45 %, regardless of the radius. Understanding of laps of the visually handicapped were 70-80 % and that of the s.m.w. were 50-70%. It appeared that the s.m.w. had difficulty understanding 3/4 laps. The larger the radius was, the smaller both the visually handicapped and the s.m.w. could sense the radius. They sensed the radius as 60-70% of the real radius in the 5m radius. The visually handicapped sensed the radius as 1.2 times of it in the 2m radius, while the s.m.w. sensed it correctly. 2. For the two, the difference of laps was correlated with the difference of the radius. The larger the difference of laps was, the larger the difference of the radius was, or the larger the difference of the radius was, the larger the difference of laps was. The regression line of the visually handicapped was similar to that of the s.m.w., so the relationship between the difference of laps and the difference of the radius had similar characteristics for the two. 3. When the visually handicapped sensed that they could understand the laps or they walked anticlockwise, the rate of the lap difference was lower and the difference of the radius was larger. When the s.m.w. sensed that they could understand the laps, the rate of the lap difference was higher and the difference of the radius was smaller, however the rate of the lap difference and the difference of the radius was not influenced by the direction they were walking. Depending on their understanding of laps and the walking direction, their consciousness turned to one side, and the understanding of laps and the cognition of the radius were not compatible. 4. As clues for the cognition of the laps, subjects sensed acoustic echo, imaging spaces, bending degrees of the wall and sense of rotation of their body useful, however degrees of panel seam, the number of panels and the number of steps not helpful. Moreover, the feeling of the panels was useful and also not helpful as a clue. When the subjects were walking around the circler structures, some of them were conscious of the center of the circle or the starting point constantly.
Metopic craniosynostosis is a condition caused by the premature fusion of the metopic cranial suture. If untreated, it can result into brain growth restriction, increased intra-cranial pressure, ...visual impairment, and cognitive delay. Fronto-orbital advancement is the widely accepted surgical approach to correct cranial shape abnormalities in patients with metopic craniosynostosis, but the outcome of the surgery remains very dependent on the expertise of the surgeon because of the lack of objective and personalized cranial shape metrics to target during the intervention. We propose in this paper a locally affine diffeomorphic surface registration framework to create an optimal interventional plan personalized to each patient. Our method calculates the optimal surgical plan by minimizing cranial shape abnormalities, which are quantified using objective metrics based on a normative model of cranial shapes built from 198 healthy cases. It is guided by clinical osteotomy templates for fronto-orbital advancement, and it automatically calculates how much and in which direction each bone piece needs to be translated, rotated, and/or bent. Our locally affine framework models separately the transformation of each bone piece while ensuring the consistency of the global transformation. We used our method to calculate the optimal surgical plan for 23 patients, obtaining a significant reduction of malformations (p <; 0.001) between 40.38% and 50.85% in the simulated outcome of the surgery using different osteotomy templates. In addition, malformation values were within healthy ranges (p > 0.01).
Euro Banknote Recognition System for Blind People Dunai Dunai, Larisa; Chillarón Pérez, Mónica; Peris-Fajarnés, Guillermo ...
Sensors (Basel, Switzerland),
01/2017, Volume:
17, Issue:
1
Journal Article
Peer reviewed
Open access
This paper presents the development of a portable system with the aim of allowing blind people to detect and recognize Euro banknotes. The developed device is based on a Raspberry Pi electronic ...instrument and a Raspberry Pi camera, Pi NoIR (No Infrared filter) dotted with additional infrared light, which is embedded into a pair of sunglasses that permit blind and visually impaired people to independently handle Euro banknotes, especially when receiving their cash back when shopping. The banknote detection is based on the modified Viola and Jones algorithms, while the banknote value recognition relies on the Speed Up Robust Features (SURF) technique. The accuracies of banknote detection and banknote value recognition are 84% and 97.5%, respectively.
It is difficult for visually handicapped people to recognize spaces and their position when they walk on curved paths. They often have accidents or lose their way in such paths. In this study, in ...order to clarify the spatial cognition of the visually handicapped and their characteristics of the search behavior, experiments were carried out by producing 7 kinds of model paths. I made it clear whether the visually handicapped could recognize the direction of the paths, whether they could keep the direction, and how to know the direction and the clues for their spatial cognition.
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