Abstract We propose a new framework that extends the standard Probability Hypothesis Density (PHD) filter for multiple targets having N ⩾ 2 different types based on Random Finite Set theory, taking into account not only background clutter, but also confusions among detections of different target types, which are in general different in character from background clutter. Under Gaussianity and linearity assumptions, our framework extends the existing Gaussian mixture (GM) implementation of the standard PHD filter to create a N-type GM-PHD filter. The methodology is applied to real video sequences by integrating object detectors’ information into this filter for two scenarios. For both cases, Munkres’s variant of the Hungarian assignment algorithm is used to associate tracked target identities between frames. This approach is evaluated and compared to both raw detection and independent GM-PHD filters using the Optimal Sub-pattern Assignment metric and discrimination rate. This shows the improved performance of our strategy on real video sequences.
Traditionally, multi-target trackers including GNN @cite_33 , JPDAF @cite_32 , and MHT @cite_19 , are based on the concept of finding associations between targets and measurements. However, these approaches have faced challenges not only in the uncertainty caused by data association but also in algorithmic complexity that increases exponentially with the number of targets and measurements. For instance, the total number of possible hypotheses in MHT increases exponentially with time and heuristic pruning merging of hypotheses is performed to reduce computational cost.
@cite_19 @cite_32 @cite_33
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In this study, a multiple hypothesis tracking (MHT) algorithm for multi-target multi-camera tracking (MCT) with disjoint views is proposed. The authors' method forms track-hypothesis trees, and each branch of them represents a multi-camera track of a target that may move within a camera as well as move across cameras. Furthermore, multi-target tracking within a camera is performed simultaneously with the tree formation by manipulating a status of each track hypothesis. Each status represents three different stages of a multi-camera track: tracking, searching, and end-of-track. The tracking status means targets are tracked by a single camera tracker. In the searching status, the disappeared targets are examined if they reappear in other cameras. The end-of-track status does the target exited the camera network due to its lengthy invisibility. These three status assists MHT to form the track-hypothesis trees for multi-camera tracking. Furthermore, a gating technique which eliminates the unlikely observation-to-track association using space-time information has been introduced. In the experiments, the proposed method has been tested using two datasets, DukeMTMC and NLPR , which demonstrates that the method outperforms the state-of-the-art method in terms of improvement of the accuracy. In addition, real-time and online performance of proposed method is also showed in this study. This paper presents Markov chain Monte Carlo data association (MCMCDA) for solving data association problems arising in multitarget tracking in a cluttered environment. When the number of targets is fixed, the single-scan version of MCMCDA approximates joint probabilistic data association (JPDA). Although the exact computation of association probabilities in JPDA is NP-hard, we prove that the single-scan MCMCDA algorithm provides a fully polynomial randomized approximation scheme for JPDA. For general multitarget tracking problems, in which unknown numbers of targets appear and disappear at random times, we present a multi-scan MCMCDA algorithm that approximates the optimal Bayesian filter. We also present extensive simulation studies supporting theoretical results in this paper. Our simulation results also show that MCMCDA outperforms multiple hypothesis tracking (MHT) by a significant margin in terms of accuracy and efficiency under extreme conditions, such as a large number of targets in a dense environment, low detection probabilities, and high false alarm rates. Multitarget tracking (MTT) hinges upon the solution of a data association problem in which observations across scans are partitioned into tracks and false alarms so that accurate estimates of true targets can be recovered. In this chapter, we describe a methodology for solving this data association problem as a maximum weight independent set problem (MWISP). This MWISP approach has been used successfully for almost a decade in fielded sensor systems using a multiple hypothesis tracking (MHT) framework, but has received virtually no attention in the tracking literature, nor has it been recognized as an application in the clique independent set literature. The primary aim of this chapter is to simultaneously fill these two voids. Second, we show that the MWISP formulation is equivalent to the multidimensional assignment (MAP) formulation, one of the most widely documented approaches for solving the data association problem in MTT. Finally, we offer a qualitative comparison between the MWISP and MAP formulations, while highlighting other important practical issues in data association algorithms that are commonly overlooked by the optimization community. We propose a generic online multi-target track-before-detect (MT-TBD) that is applicable on confidence maps used as observations. The proposed tracker is based on particle filtering and automatically initializes tracks. The main novelty is the inclusion of the target ID in the particle state, enabling the algorithm to deal with unknown and large number of targets. To overcome the problem of mixing IDs of targets close to each other, we propose a probabilistic model of target birth and death based on a Markov Random Field (MRF) applied to the particle IDs. Each particle ID is managed using the information carried by neighboring particles. The assignment of the IDs to the targets is performed using Mean-Shift clustering and supported by a Gaussian Mixture Model. We also show that the computational complexity of MT-TBD is proportional only to the number of particles. To compare our method with recent state-of-the-art works, we include a postprocessing stage suited for multi-person tracking. We validate the method on real-world and crowded scenarios, and demonstrate its robustness in scenes presenting different perspective views and targets very close to each other.