Robust Mobile Object Tracking Based on Multiple Feature Similarity and Trajectory Filtering

This paper presents a new algorithm to track mobile objects in different scene conditions. The main idea of the proposed tracker includes estimation, multi-features similarity measures and trajectory filtering. A feature set (distance, area, shape ratio, color histogram) is defined for each tracked object to search for the best matching object. Its best matching object and its state estimated by the Kalman filter are combined to update position and size of the tracked object. However, the mobile object trajectories are usually fragmented because of occlusions and misdetections. Therefore, we also propose a trajectory filtering, named global tracker, aims at removing the noisy trajectories and fusing the fragmented trajectories belonging to a same mobile object. The method has been tested with five videos of different scene conditions. Three of them are provided by the ETISEO benchmarking project (http://www-sop.inria.fr/orion/ETISEO) in which the proposed tracker performance has been compared with other seven tracking algorithms. The advantages of our approach over the existing state of the art ones are: (i) no prior knowledge information is required (e.g. no calibration and no contextual models are needed), (ii) the tracker is more reliable by combining multiple feature similarities, (iii) the tracker can perform in different scene conditions: single/several mobile objects, weak/strong illumination, indoor/outdoor scenes, (iv) a trajectory filtering is defined and applied to improve the tracker performance, (v) the tracker performance outperforms many algorithms of the state of the art

Multiple-shot Human Re-Identification by Mean Riemannian Covariance Grid

International audienceHuman re-identification is defined as a requirement to determine whether a given individual has already appeared over a network of cameras. This problem is particularly hard by significant appearance changes across different camera views. In order to re-identify people a human signature should handle difference in illumination, pose and camera parameters. We propose a new appearance model combining information from multiple images to obtain highly discriminative human signature, called Mean Riemannian Covariance Grid (MRCG). The method is evaluated and compared with the state of the art using benchmark video sequences from the ETHZ and the i-LIDS datasets. We demonstrate that the proposed approach outperforms state of the art methods. Finally, the results of our approach are shown on two other more pertinent datasets

Body parts detection for people tracking using trees of Histogram of Oriented Gradient descriptors

International audienceVision algorithms face many challenging issues when it comes to analyze human activities in video surveillance applications. For instance, occlusions makes the detection and tracking of people a hard task to perform. Hence advanced and adapted solutions are required to analyze the content of video sequences. We here present a people detection algorithm based on a hierarchical tree of Histogram of Oriented Gradients referred to as HOG. The detection is coupled with independently trained body part detectors to enhance the detection performance and to reach state of the art performances. We adopt a person tracking scheme which calculates HOG dissimilarities between detected persons throughout a sequence. The algorithms are tested in videos with challenging situations such as occlusions. False alarms are further reduced by using 2D and 3D information of moving objects segmented from a background reference frame

Haar like and LBP based features for face, head and people detection in video sequences

International audienceActual computer vision algorithms cannot extract semantic information of people activity coming from the large and increasing amount of surveillance cameras installed around the world. Algorithms need to analyse video content at real time frame rate and with a false alarm detection rate as small as possible. Such algorithms can be dedicated and specifically parameterised in certain applications and restrained environment. To make algorithms as useful as possible, they need to tackle many challenging issues in order to correctly analyse human activties. For instance, people are rarely entirely seen in a video because of static (contextual object or they are partly seen by the camera field of view) and dynamic occlusion (e.g. person in front of another). We here present a novel people, head and face detection algorithm using Local Binary Pattern based features and Haar like features which we refer to as couple cell features. An Adaboost training scheme is adopted to train object features. During detection, integral images are used to speed up the process which can reach several frames per second in surveillance videos

People detection and re-identification for multi surveillance cameras

International audienceRe-identifying people in a network of non overlapping cameras requires people to be accurately detected and tracked in order to build a strong visual signature of people appearances. Traditional surveillance cameras do not provide high enough image resolution to iris recognition algorithms. State of the art face recognition can not be easily applied to surveillance videos as people need to be facing the camera at a close range. The different lighting environment contained in each camera scene and the strong illumination variability occurring as people walk throughout a scene induce great variability in their appearance. %In addition, surveillance scene often display people whose images occlud each other onto the image plane making people detection difficult to achieve. In addition, people images occlud each other onto the image plane making people detection difficult to achieve. We propose a novel simplified Local Binary Pattern features to detect people, head and faces. A Mean Riemannian Covariance Grid (MRCG) is used to model appearance of tracked people to obtain highly discriminative human signature. The methods are evaluated and compared with the state of the art algorithms. We have created a new dataset from a network of 2 cameras showing the usefulness of our system to detect, track and re-identify people using appearance and face features

Person Re-identification Using Spatial Covariance Regions of Human Body Parts

International audienceIn many surveillance systems there is a requirement to determine whether a given person of interest has already been observed over a network of cameras. This is the person re-identification problem. The human appearance obtained in one camera is usually different from the ones obtained in another camera. In order to re-identify people the human signature should handle difference in illumination, pose and camera parameters. We propose a new appearance model based on spatial covariance regions extracted from human body parts. The new spatial pyramid scheme is applied to capture the correlation between human body parts in order to obtain a discriminative human signature. The human body parts are automatically detected using Histograms of Oriented Gradients (HOG). The method is evaluated using benchmark video sequences from i-LIDS Multiple-Camera Tracking Scenario data set. The re-identification performance is presented using the cumulative matching characteristic (CMC) curve. Finally, we show that the proposed approach outperforms state of the art methods

Boosted human re-identification using Riemannian manifolds

International audienceThis paper presents an appearance-based model to address the human re-identification problem. Human re-identification is an important and still unsolved task in computer vision. In many systems there is a requirement to identify individuals or determine whether a given individual has already appeared over a network of cameras. The human appearance obtained in one camera is usually different from the ones obtained in another camera. In order to re-identify people a human signature should handle difference in illumination, pose and camera parameters. The paper focuses on a new appearance model based on Mean Riemannian Covariance (MRC) patches extracted from tracks of a particular individual. A new similarity measure using Riemannian manifold theory is also proposed to distinguish sets of patches belonging to a specific individual. We investigate the significance of MRC patches based on their reliability extracted during tracking and their discriminative power obtained by a boosting scheme. Our method is evaluated and compared with the state of the art using benchmark video sequences from the ETHZ and the i-LIDS datasets. Re-identification performance is presented using a cumulative matching characteristic (CMC) curve. We demonstrate that the proposed approach outperforms state of the art methods. Finally, the results of our approach are shown on two further and more pertinent datasets

Relative Dense Tracklets for Human Action Recognition

International audienceThis paper addresses the problem of recognizing human actions in video sequences for home care applications. Recent studies have shown that approaches which use a bag-of-words representation reach high action recognition accuracy. Unfortunately, these approaches have problems to discriminate similar actions, ignoring spatial information of features. As we focus on recognizing subtle differences in behaviour of patients, we propose a novel method which significantly enhances the discriminative properties of the bag-of-words technique. Our approach is based on a dynamic coordinate system, which introduces spatial information to the bag-of-words model, by computing relative tracklets. We perform an extensive evaluation of our approach on three datasets: popular KTH dataset, challenging ADL dataset and our collected Hospital dataset. Experiments show that our representation enhances the discriminative power of features and bag-of-words model, bringing significant improvements in action recognition performance

Online Parameter Tuning for Object Tracking Algorithms

International audienceObject tracking quality usually depends on video scene conditions (e.g. illumination, density of objects, object occlusion level). In order to overcome this limitation, this article presents a new control approach to adapt the object tracking process to the scene condition variations. More precisely, this approach learns how to tune the tracker parameters to cope with the tracking context variations. The tracking context, or context, of a video sequence is defined as a set of six features: density ofmobile objects, their occlusion level, their contrastwith regard to the surrounding background, their contrast variance, their 2D area and their 2D area variance. In an offline phase, training video sequences are classified by clustering their contextual features. Each context cluster is then associated to satisfactory tracking parameters. In the online control phase, once a context change is detected, the tracking parameters are tuned using the learned values. The approach has been experimentedwith three different tracking algorithms and on long, complex video datasets. This article brings two significant contributions: (1) a classification method of video sequences to learn offline tracking parameters and (2) a newmethod to tune online tracking parameters using tracking context

Management of Large Video Recordings

International audienceThe management and extraction of structured knowledge from large video recordings is at the core of urban/environment planning, resource optimization. We have addressed this issue for the networks of camera deployed in two underground systems in Italy. In this paper we show how meaningful events are detected directly from the streams of video. Later in an off-line analysis we can set this information into an adequate knowledge model representation that will allow us to model behavioral activity and obtain statistics on everyday people activities in metro station. Raw data as well as online and off-line metadata are stored in relational databases with spatiotemporal retrieval capabilities and allow the end-user to analyse different video recording periods