In this paper we propose an electronic travel aid system for the visually impaired that utilizes interactive sonification of U-depth maps of the environment. The system is comprised of a depth sensor connected to a mobile device and a dedicated application for segmenting depth images and converting them into sounds in real time. An important feature of the system is that the user can interactively select the 3D scene region for sonification by simple touch gestures on the mobile device screen. The sonification scheme is using stereo panning for azimuth angle localization of scene objects, loudness for their size and frequency for distance encoding. Such a sonic representation of 3D scenes allows the user to identify the geometric structure of the environment and determine the distances to potential obstacles. The prototype application was tested by three visually impaired users who managed to successfully perform indoor mobility tasks. The system's usefulness was evaluated quantitatively by means of system usability and task-related questionnaires.
In this article a new approach for 3D reconstruction of thermal scene is presented. The system consists of two cameras: thermal and visual. The reconstructed object is observed from at least two different viewpoints by the two cameras. The two images either from thermal camera or visual one constitute a stereoscopic set. By means of corresponding feature points extracted from the pair of either thermal or visual images, the relative position of the two viewpoints is evaluated. Then the images are rectified and the standard stereo reconstruction is performed on either thermal or visual images depending on the scene conditions, i.e. depending on the number and quality of feature points extracted from the thermal and visual pairs. The relative position of the two viewpoints is established only up to some scalar factor. To establish the relative position with respect to some metric value two approaches were applied: (a) based on a known distance between two points in 3D space and (b) based on an additional approximate 3D reconstruction of a given point by the thermal and visual camera pair treated as a stereoscopic set. The designed application which performs the calibration of the system and 3D scene reconstruction is described and the obtained results are presented.
1.http://dx.
The aim of the presented work was the development of a tracking algorithm for a stereoscopic camera setup equipped with an additional inertial sensor. The input of the algorithm consists of the image sequence, angular velocity and linear acceleration vectors measured by the inertial sensor. The main assumption of the project was fusion of data streams from both sources to obtain more accurate ego-motion estimation. An electronic module for recording the inertial sensor data was built. Inertial measurements allowed a coarse estimation of the image motion field that has reduced its search range by standard image-based methods. Continuous tracking of the camera motion has been achieved (including moments of image information loss). Results of the presented study are being implemented in a currently developed obstacle avoidance system for visually impaired pedestrians.
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