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A robust computer vision system for an unmanned surface vehicle (USV) is being developed, in support of tracking a moving marine vehicle from the USV. A methodology to minimize the tracking errors regarding the raw 2-D measurements of the position of a target boat using a commercial stereo camera will be presented. This errors are mainly due to image quantization limitations and pixel miscorrespondences...
Camera calibration constitutes a basic problem in many robot applications. In this paper two algorithms tailored to the calibration of the parameters of a depth camera are proposed. More precisely, a closed form solution that requires the coordinates of three corresponding points in the world and the camera coordinates systems, for the noise free case is proposed. Moreover, a robust algorithm that...
An algorithm is presented to automate the identification of breaking waves in images collected with a camera on a drifting buoy. Each image is given a score from four separate analysis techniques: brightness detection, pixel histogram, entropy (texture) analysis, and glare identification. By combining these in a composite score, potential breaking wave images are detected and the number of images...
This paper proposes three techniques to reduce the computational cost, both in terms of memory and CPU usage, of visual underwater trajectory-based SLAM. On the one hand, geometric constraints involving the camera Field of View (FOV) are used to decide when a new node has to be added to the trajectory estimate. On the other hand, the camera FOV geometry is also used to preselect the candidate images...
Most existing vision-based methods for gaze tracking need a tedious calibration process. In this process, subjects are required to fixate on a specific point or several specific points in space. However, it is hard to cooperate, especially for children and human infants. In this paper, a new calibration-free gaze tracking system and method is presented for automatic measurement of visual acuity in...
Falls are a common cause of injuries and traumas for elderly and could be life threatening. Delivering a prompt medical support after a fall is essential to prevent lasting injuries. Therefore, effective fall detection could provide urgent support and dramatically reduce the risk of such mishaps. In this paper, we propose a hierarchical classification framework based on a novel anatomical-plane-based...
This paper presents a monocular camera (MC) and inertial measurement unit (IMU) integrated approach for indoor position estimation. Unlike the traditional estimation methods, we fix the monocular camera downward to the floor and collect successive frames where textures are orderly distributed and feature points robustly detected, rather than using forward oriented camera in sampling unknown and disordered...
Recently, the direction-of-arrival (DOA) estimation using an array antenna has been studied extensively. Accordingly, array calibration method has also become an important topic. Conventional data acquisition methods often require a positioner or an azimuth table to make sources of known DOAs for pre-measurement of array calibration in a radio anechoic chamber. However, such a measurement is both...
In order to establish a comprehensive automatic visual surveil-lance system, many researches aimed at tracking objects for high-precision and recognized objects for high accuracy. The process of these technologies involves a lot of computation load and even highly complex algorithms to meet the requirement. However, while implementing these technologies for the application in embedded systems or low-end...
Gesture recognition is increasingly remarkable in the field of HCI, since hand motions and gestures enable users to interact with computers in more natural ways. This paper focuses on two-hand gesture recognition and proposes a Kinect-based method which specially takes a certain static gesture as a start and end mark of a dynamic gesture. Furthermore, we use an innovative way to extract the feature...
In this paper we present a system for humanrobot cooperation where a flexible beam is handled by a human and robot. We use a vision based state estimator to coordinate the robot with the human. The state estimator is based on particle filtering, and the dynamical behaviour of the flexible beam is described by a finite element model, more specifically the absolute nodal coordinate formulation. We present...
We present a hardware architecture for real-time digital video stabilization in high-performance embedded systems. The stabilization algorithm analyzes the current and past video frames and obtains a motion estimation vector, which is then filtered to isolate unwanted camera movements from intentional panning. The vector is then used to correct the output video frame. We designed a hardware architecture...
The measurement of bulky forgings belongs to large size measurement under complex conditions. It needs high efficient and precision automatic non-contact measuring method in real time with high resolution. In this paper, an online measurement method is proposed based on single stripe structured light and liner camera scanning together. We choose liner CCD camera with excellent frequency response and...
A new geometric framework, called generalized coupled line camera (GCLC), is proposed to derive an analytic solution to reconstruct an unknown scene quadrilateral and the relevant projective structure from a single or multiple image quadrilaterals. We extend the previous approach developed for rectangle to handle arbitrary scene quadrilaterals. First, we generalize a single line camera by removing...
Most of the open challenges in person re-identification arise from the large variations of human appearance and from the different camera views that may be involved, making pure feature matching an unreliable solution. To tackle these challenges state-of-the-art methods assume that a unique inter-camera transformation of features undergoes between two cameras. However, the combination of view points,...
The projection surface of a 3D line in a non-central camera is a ruled surface, containing the complete information of the 3D line. The resulting line-image is a curve which contains the 4 degrees of freedom of the 3D line. In this paper we investigate the properties of the line-image in conical catadioptric systems. This curve is a particular quartic that can be described by only six homogeneous...
In the field of active perception, object search is a widely studied problem. To search for an object in large rooms, it would be expensive to explore and check each object's similarity with the object of interest. The expense could uncontrollably bloat as the number of objects to be searched increases. If the objects are of the order of a 2-5cm, they appear very small, making it difficult for the...
We propose a fast-adapted subspace tracking algorithm for background subtraction in video surveillance. While background scenes are modelled as a linear combination of basis images, foreground scenes are regarded as a sparse image. Every time a video frame streams in, two alternating procedures are repeatedly done: basis images are updated by a recursive least square algorithm and foreground images...
This paper presents a study of an important imaging system, called the plate refractive imaging system. The system comprises of a perspective camera looking through one or more planar parallel plates to the target imaging environment. Such as the perspective camera captures the object through an infrared filter which is used in the infrared navigator for surgeries. Sometimes, we have to calibrate...
In this paper, we revisit the problem of estimating the trifocal tensor from image line measurements. With measurements of corresponding lines in three views, a linear method [1] requiring 13 lines was developed to estimate the trifocal tensor from which projective reconstruction of the scene is made possible. By further utilizing the nonlinear constraints on the trifocal tensor, we propose several...
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