Correspondence problem (Total 274894 Papers Found)

This chapter starts with a brief introduction into model-based segmentation, explaining the basic concepts and different approaches. Subsequently, two segmentation approaches are presented in more detail: First, the method of deformable simplex meshes is described, explaining the special properties of the simplex mesh and the formulation of the internal forces. Common choices for image forces are presented, and how to evolve the mesh to adapt to certain structures. Second, the method of point-ba ...
In complex propagation environments with multipath reflections determining the time-of-arrival (TOA) of the line-of-sight (LoS) signal, which is required for localization, is challenging. As a result the localization accuracy of TOA-based systems degrade in such environments. We are pursuing a novel approach where the TOA algorithm returns not one but multiple candidate TOA values as this list is more likely to contain the LoS TOA value and the localization algorithm uses all of these to form a ...
We present a linear rectiication algorithm for general, unconstrained stereo rigs. The algorithm takes the two perspective projection matrices of the original cameras, and computes a pair of rectifying projection matrices. We report tests proving the correct behaviour of our method, as well as the negligible decrease of the accuracy of 3-D reconstruction if performed from the rectiied images directly. To maximise reproducibility and usefulness, we give a working, 20-line MATLAB code, and a URL w ...
In this paper, a kind of integrated perception system for mobile robot is presented, which consists of 3D Lidar, 2D camera and their spatial registration. Based on the system and support vector machine (SVM), a self-supervised learning scheme between 3D point cloud data and 2D image data has been established, which can identify the traversable lane in driving environments through data association and parameters training. With this approach, vision-based autonomous navigation can be achieved and ...
Data association is the key technique to solve the multiple-target tracking problems. A new approach to tracking algorithm for radar system based on the neural network is investigated in this paper. The proposed algorithm will solve both the data association and the target tracking problems simultaneously. With this approach, the matching between radar measurements and existing target tracks can achieve a global consideration. Moreover, one simple detection and estimation algorithm denoted adapt ...
This paper presents a simple OFDM-based MIMO radar for real-time area surveillance applications. The radar is able to estimate range, velocity and azimuthal positions of multiple objects simultaneously within one transmit cycle. Detection, clustering, data association and tracking are then performed to estimate the number of targets, extract the target trajectories and improve the positioning accuracy. The radar processing and algorithms have been chosen so that a real-time implementation is fea ...
This paper proposes a topological mapping technique that utilises persistent SIFT features to reduce the amount of data storage required. It delivers, as an output, a topological map that lends itself well to conventional path planning techniques. The approach assimilates features into a statistical model which promises improved data association. Experiments were performed using omnidirectional camera images from the Cogniron dataset. A map was constructed from one of the supplied routes and the ...
Motion information is extracted by identifying the temporal signature associated with the textured objects in the scene. In this paper, we present a new computational framework for motion perception. Our methodology considers spatiotemporal frequency (STF) domain analysis to extract the optical ow information. First, we show that a sequence of image frames can be used to extract the motion parameters for the diier-ent regions in a dynamic scene using the basic Fourier transform properties in the ...
This paper shows an approach to improve the statistical validity of orbital estimates and uncertainties as well as a method of associating measurements with the correct space objects. The approach involves using an adaptive Gaussian mixture solution to the Fokker-Planck-Kolmogorov equation for its applicability to the space object tracking problem. The Fokker-Planck-Kolmogorov equation describes the timeevolution of the probability density function for nonlinear stochastic systems with Gaussian ...
We introduce photometric stereo reconstruction for surface analysis of mucosal tissue. Photometric stereo captures images of a surface from a single camera, but illuminated from different light sources. From the set of images, a detailed surface reconstruction is estimated. We apply photometric stereo principles to mucosal tissue, which raises technical challenges due to its specular appearance. Following reconstruction of the surface, we apply surface analysis techniques based on differential g ...
In this paper we consider the problem of reconstructing triangular surfaces from given contours. An algorithm solving this problem has to decide which contours of two successive slices should be connected by the surface (branching problem), and, given that, which vertices of the assigned contours should be connected for the triangular mesh (correspondence problem). We present a new approach that solves both tasks in an elegant way. The main idea is to employ discrete distance fields enhanced wit ...
This paper presents a method to extend the normalized direct linear transform (DLT) algorithm for homography estimation. Previously, only point correspondences were used. Now, line correspondences can be included as well. This extension is point-centric in that the lines are normalized to fit with the normalization used for points. Therefore, this method will be most useful if there are more point correspondences than line correspondences. The main contribution of this paper is the derivation of ...
Multi-object tracking (MOT) in airborne video is a challenging problem due to the uncertain airborne vehicle motion as well as mounted camera vibrations. Most approaches addressing tracking in such type of scenario, use data association based on motion detection responses. Such approaches fail tracking objects with low speed or static ones. To alleviate the motion detection failures, in this paper we propose a multi-object tracking system based on combining motion-detection and Compressive Track ...
We solve the correspondence problem with integrate and fire models. Taking into account the requirement for rapid processing, we use a spike timing code, associated with receptive fields and Winner Takes all Strategy. We study through computer experiments the properties and performance of various shapes of receptive fields. We use a perfect Integrate and Fire model, and we study the interest of adding a leakage to it. ...
There are several strategies of how to retrieve depth information from a sequence of images, like depth from motion, depth from shading and depth from stereopsis. In this paper, we introduce a new method to retrieve depth based on motion and stereopsis. A motion detection representation helps establishing further correspondences between different motion information. This representation bases in the permanency memories mechanism, where jumps of pixels between grey level bands are computed in a ma ...
Robotic-assisted minimally invasive surgery (RMIS) has attracted the attention of the surgeon and patient with high precision, minimizing trauma, dexterity and fast recovery time. The three-dimensional reconstruction of tissue structure and morphology during operation is an important prerequisite to guide the operation accurately and safely. However, hole problem still exists in the reconstruction process that will affect the accuracy and effectiveness of the surgery procedure. To address this p ...
Multiple target tracking techniques require data association that operates in conjunction with filtering. When multiple targets are closely spaced, the conventional approach (MHT/assignment) may not give satisfactory results, mainly due to the difficulty in deciding the number of targets. Recently, the first moment of the "multi-target posterior density", called the probability hypothesis density (PHD), has been proposed to address the multi-target tracking problem. Particle filtering techniques ...
In this paper we focus on the multi-robot perception problem, and present an experimentally validated end-to-end multi-robot mapping framework, enabling individual robots in a team to see beyond their individual sensor horizons. The inference part of our system is the DDF-SAM algorithm [1], which provides a decentralized communication and inference scheme, but did not address the crucial issue of data association. One key contribution is a novel, RANSAC-based, approach for performing the between ...
Reconstruction of 3D curves from their stereo images is an important issue in computer vision. Based on deformation of the snake model and NURBS representation, we evolve the curve in the view of inverse optimization to finish reconstruction. This manner can reduce the need of matching multi-view space curve projections, meanwhile improve the reconstruction precision. Considering that the 2D data reconstruction exists error inevitably, based on two cameras, a discussion on its influence to stere ...
This paper addresses the frame-to-frame data association and state estimation problems in localization of a pedestrian relative to a moving vehicle from a monocular far infra-red video sequence. Using a novel application of the hierarchical model-based motion estimation framework, we are able to use the image appearance information to solve the frame-to-frame data association problem and estimate a sub-pixel accurate height ratio for a pedestrian in two frames. Then, to localize the pedestrian, ...
Panoramic distance maps can provide valuable information for mobile robot navigation. An approach to obtain such distance maps is to implement a stereoscopic system using two hyperboloidal catadioptric sensors. This paper analyzes the effects over distance estimation of two typical arrangements of the mirrors. In one of the arrangements the mirrors are placed along a vertical axis, while in the other configuration the sensors are located on plane. Both configurations may yield similar distance e ...
In this paper we propose a new solution to the problem of model-based pose estimation and pose tracking, using a sequence of stereo images in which a small number of landmarks are detected on the object of interest. The landmarks are reconstructed in 3D and then the simultaneous pose and correspondence problem is solved with a novel algorithm, PC-SCO, based on stochastic combinatorial optimization. We also use a new algorithm, quaternion-based characteristic polynomial (QCP), which significantly ...
We introduce a novel framework for soft-input, soft-output (SISO) equalization in frequency selective multipleinput multiple-output (MIMO) channels based on the well-known belief propagation (BP) algorithm. As in the BP equalizer, we model the multipath channels using factor graphs (FGs) where the transmitted and received signals are represented by the function and variable nodes respectively. The edges connecting the function and variable nodes illustrate the dependencies of the multipath chann ...
In prior work, we developed a speaker tracking system based on an extended Kalman filter using time delays of arrival (TDOAs) as acoustic features. While this system functioned well, its utility was limited to scenarios in which a single speaker was to be tracked. In this work, we remove this restriction by generalizing the IEKF, first to a probabilistic data association filter, which incorporates a clutter model for rejection of spurious acoustic events, and then to a joint probabilistic data a ...
The goal of the visual correspondence problem is to establish a connectivity pattern (a mapping) between two images such that features projected from the same scene point are connected. Dynamic link matching (DLM) is a self-organizing dynamical system to establish such connectivity patterns for object recognition, but with rather naturally given simple interactions between pattern elements, its organizing process is slow. Here we propose to stabilize (store) established mappings so that they can ...
In this paper, we present an overview of the literature for particle filtering under measurement origin uncertainty with an emphasize on single scan data association algorithms. We compare some of the existing and newly proposed joint state particle filtering algorithms for the closely spaced target tracking problem. Both maximum a posteriori (MAP) and minimum mean square error (MMSE) estimation outputs of four different algorithms are compared. We also include MMSE outputs of a non-joint (indep ...
Object discovery and modeling have been widely studied in the computer vision and robotics communities. SLAM approaches that make use of objects and higher level features have also recently been proposed. Using higher level features provides several benefits: these can be more discriminative, which helps data association, and can serve to inform service robotic tasks that require higher level information, such as object models and poses. We propose an approach for online object discovery and obj ...
When tracking multiple objects in an image sequence, various difficulties such as occlusion, mis-detection, false detection, and abrupt camera motion often occur together. Nevertheless, previous methods on multi-object tracking generally focus on only one or two of them. For that reason, the previous methods could not handle various problematic situations, where multiple difficulties occur simultaneously. To overcome this limitation, we propose a unified framework that can handle such difficulti ...
This paper presents a sensor fusion strategy applied for Simultaneous Localization and Mapping (SLAM) in dynamic environments. The designed approach consists of two features: (i) the first one is a fusion module which synthesizes line segments obtained from laser rangefinder and line features extracted from monocular camera. This policy eliminates any pseudo segments that appear from any momentary pause of dynamic objects in laser data. (ii) The second characteristic is a modified multi-sensor p ...
⎯This paper proposes a simple geometrical ray based approach to solve the stereo correspondence problem for the single-lens bi-prism stereovision system. Each image captured using this system can be divided into two sub-images on the left and right and these sub-images are generated by two virtual cameras which are produced by the bi-prism. This stereovision system is equivalent to the conventional two camera system and the two sub-images captured have disparities which can be used to reconstr ...
One of the goals in the field of mobile robotics is the development of mobile platforms which operate in populated environments. For many tasks it is therefore highly desirable that a robot can track the positions of the humans in its surrounding. In this paper we introduce sample-based joint probabilistic data association filters as a new algorithm to track multiple moving objects. Our method applies Bayesian filtering to adapt the tracking process to the number of objects in the perceptual ran ...
Automatic pedestrian detection and tracking is an important issue in the field of computer vision and robot navigation. We propose a scheme to implement multi-pedestrian tracking in a scene obtained by a static camera. We combine HOG and HOF features to describe the characteristics of persons. AdaBoost algorithm is then utilized to train a strong classifier for better detection accuracy of persons. We use particle filter as the tracking framework and train a online SVM classifier, which is the o ...
A method for feature selection in visual simultaneous localization and mapping (SLAM) is presented based on the potential data association cost. It is put into practice through a mechanism termed predictive virtual matching test, which measures the goodness of any new feature by examining the predictive repeatability and compatibility with the other features and potential candidates. For each new feature, the test is conducted in its predictive virtual search region (PVSR) in the image frame whe ...
The fuzzy recursive least squares-probabilistic data association (FRLS-PDA) filter is presented for tracking single maneuvering target in cluttered situations with unknown process noises. In the proposed filter, the association probabilities of the current valid measurements belonging to a motion target are calculated by the probabilistic data association (PDA) algorithm. Then these probabilities are used to weight the valid measurements for generating a fused measurement, which is applied to de ...
One way to visualize the association of semi-structured data is to show the structure of its schemas. We developed an interactive service system using of a method for self-organizing schema structure, an application of self-organizing mapping. A graph structure is generated by estimating data association as a link between field names in relational tables. This facilitates exploratory visualization in data lakes. Experiment results obtained with a prototype system demonstrated the method's practi ...
The development of driverless vehicles capable of moving on urban roads could provide important benefits in reducing accidents, in increasing life comfort and in providing cost savings. In this dissertation we discuss how to create a perception system allowing robots to drive on roads, without the need to adapt the infrastructure, without requiring previous visits, and considering possible the presence of pedestrians and cars. We argue that the perception process is application specific and by n ...
Collectively moving object clusters are of particular interest in certain applications and have to be tracked as separate aggregated entities consisting of an unknown number of individuals. Tracking of convoys or larger vehicles in wide area ground surveillance are important examples. The objects of interest are usually considered as point source objects, i. e., compared to the sensor resolution their spatial extension is neglected, though increasing resolution capabilities of modern sensors may ...
This paper proposes a simple and practical approach to perform underwater visual SLAM. The proposal improves the traditional EKF-SLAM by adopting a Trajectory-based schema that reduces the computational requirements. Linearization errors are also reduced by means of an IEKF. One of the most important parts of the proposed SLAM approach is robust image registration, which is used in the data association step making it possible to close loops reliably. Thanks to that, as shown in the experiments, ...
In this paper, we propose a new algorithm to establish the data association between a camera and a 2-D LIght Detection And Ranging sensor (LIDAR). In contrast to the previous works, where data association is established by calibrating the intrinsic parameters of the camera and the extrinsic parameters of the camera and the LIDAR, we formulate the map between laser points and pixels as a 2-D homography. The line-point correspondence is employed to construct geometric constraint on the homography ...
The paper presents a system for automatic, geo-registered, real-time 3D reconstruction from video of urban scenes. The system collects video streams, as well as GPS and inertia measurements in order to place the reconstructed models in geo-registered coordinates. It is designed using current state of the art real-time modules for all processing steps. It employs commodity graphics hardware and standard CPU’s to achieve real-time performance. We present the main considerations in designing the ...
An algorithm for multi-human detection and recognition in complex scene is proposed. It executes multihuman detection and recognition from spatial domain and time domain. In spatial domain, it establishes the Gaussian mixture background model to obtain target windows by the background difference and the foreground connection judgment. Based on target detection, a new target size estimation method is carried out through the computation of depth of field in the scene. Each target eigenvector is ex ...
The target tracking using multistatic passive radar in a digital audio/video broadcast (DAB/DVB) network with illuminators of opportunity faces two main challenges: the first challenge is that one has to solve the measurement-to-illuminator association ambiguity in addition to the conventional association ambiguity between the measurements and targets, which introduces a significantly complex three-dimensional (3-D) data association problem among the target-measurement illuminator, this is becau ...
The Bayesian online change point detection (BOCPD) algorithm provides an efficient way to do exact inference when the parameters of an underlying model may suddenly change over time. BOCPD requires computation of the underlying model’s posterior predictives, which can only be computed online in O(1) time and memory for exponential family models. We develop variational approximations to the posterior on change point times (formulated as run lengths) for efficient inference when the underlying m ...
A particle filter (PF) is a recursive numerical technique which uses random sampling to approximate the optimal solution to target tracking problems involving nonlinearities and/or non-Gaussianity. A set of particle filtering methods for tracking and manoeuvering target in clutter from angle-only measurements is presented and evaluated. The aim is to compare PFs to a well-established tracking algorithm, the IMM-PDA-EKF (interacting multiple model, probabilistic data association, extended Kalman ...
In this paper, an algorithm is proposed for tracking a highly maneuvering target in the presence of clutter by fusion of multiple detection radar and infrared sensor. It is presented by combining interactive multiple model (IMM) and multiple detection probabilistic data association filter (MDPDAF) in a multi-sensor (radar and infrared) scenario known as IMM/MS-MDPDAF algorithm. Multiple radar detection could be due to multipath or extended nature of the target such that in each scan there would ...
Merging and splitting of objects cause challenges for visual tracking. This is due to observation ambiguity, object lost, and tracking errors when objects are close together. In this paper, we propose a method to combine the joint probabilistic data association (JPDA) and the particle filter to maintain tracks of objects. The results of JPDA are employed to improve the observation model in the particle filter. Based on the ability of handling missing detections and clutter of JPDA, tracks of obj ...
Perceiving or understanding the environment surrounding of a vehicle is a very important step in building driving assistant systems or autonomous vehicles. In this thesis, we study problems of simultaneous localization and mapping (SLAM) with detection, classification and tracking moving objects in context of dynamic outdoor environments focusing on using laser scanner as a main perception sensor. It is believed that if one is able to accomplish these tasks reliably in real time, this will open ...
Complex track stitching problems have risen in prominence with the development of wide area persistent sensors for urban surveillance. Common approaches such as multiple hypothesis algorithms in tracking and tracklet stitching solve these problems by creating a representation of all possible data associations, then solving for the optimal data association via integer programming or suboptimal techniques. The number of data association hypotheses grows exponentially with number of objects and tim ...
— For subcontext-free language families K' and noncontext-free families K we consider the problem, if there is an algorithm to décide for ail Le K whether or not LeK'. Under the assumption that K and K' contain special languages related to the Post Correspondence Problem, this question is shown undecidable. Thisgives a simple and directproof for a number of wellknown results and yields also several new ones. Résumé. — Nous considérons, pour des familles de langages K' contenues dans les ...