Tracklet clustering for robust multiple object tracking using distance dependent Chinese restaurant processes

To contrive an accurate and efficient strategy for object detection–object track assignment problem, we present a tracklet clustering approach using distance dependent Chinese restaurant processes (ddCRPs), which employ a two-level robust object tracker. The first level is an ordinary tracklet generator that obtains short yet reliable tracklets. In the second level, we cluster the tracklets over time based on color, spatial and temporal attributes, where the nonparametric process of clustering with ddCRPs allows us to maintain an unknown number of objects. Unlike the previously proposed Chinese restaurant processes and Dirichlet process mixture models, our ddCRPs method does not require prescribed complex cluster models to be initialized and updated, and thus, we can cluster complex tracklets by only computing similarities between them. Our comparative evaluations on tracking different object types demonstrate the generality of our approach.     

Real-time decentralized articulated motion analysis and object tracking from videos.

In this paper, we present two new articulated motion analysis and object tracking approaches: the decentralized articulated object tracking method and the hierarchical articulated object tracking method. The first approach avoids the common practice of using a high-dimensional joint state representation for articulated object tracking. Instead, we introduce a decentralized scheme and model the interpart interaction within an innovative Bayesian framework. Specifically, we estimate the interaction density by an efficient decomposed interpart interaction model. To handle severe self-occlusions, we further extend the first approach by modeling high-level interunit interaction and develop the second algorithm within a consistent hierarchical framework. Preliminary experimental results have demonstrated the superior performance of the proposed approaches on real-world videos in both robustness and speed compared with other articulated object tracking methods.     

A novel hierarchical data association with dynamic viewpoint model for multiple targets tracking

A new framework of hierarchical data association tracking (HDAT) with branch partition, candidate upgrading and incremental motion pairing inference is proposed to resolve the problem of online multiple targets tracking. Branch partition divides the process into several independent parts so as to reduce the computational complexity on affinity. Candidate upgrading improves the robustness of target initialization by tracking potential targets and incremental motion pairing inference could benefit the occlusion handling. Furthermore, a dynamic viewpoint model (DVM) and its iterative computation algorithm are developed for tracking multiple targets under moving camera videos. Extensive data experiments on several public benchmarks show that the presented approach achieves comparable results to state-of-the-art on static camera videos and promising results on moving camera videos, and moreover, the runtime performance is significantly improved.     

Detecting spatiotemporal irregularities in videos via a 3D convolutional autoencoder

Spatiotemporal irregularities (i.e., the uncommon appearance and motion patterns) in videos are difficult to detect, as they are usually not well defined and appear rarely in videos. We tackle this problem by learning normal patterns from regular videos, while treating irregularities as deviations from normal patterns. To this end, we introduce a 3D fully convolutional autoencoder (3D-FCAE) that is trainable in an end-to-end manner to detect both temporal and spatiotemporal irregularities in videos using limited training data. Subsequently, temporal irregularities can be detected as frames with high reconstruction errors, and irregular spatiotemporal patterns can be detected as blurry regions that are not well reconstructed. Our approach can accurately locate temporal and spatiotemporal irregularities thanks to the 3D fully convolutional autoencoder and the explored effective architecture. We evaluate the proposed autoencoder for detecting irregular patterns on benchmark video datasets with weak supervision. Comparisons with state-of-the-art approaches demonstrate the effectiveness of our approach. Moreover, the learned autoencoder shows good generalizability across multiple datasets.     

Saliency Combined Particle Filtering for Aircraft Tracking

Multimedia event detection has become a popular research topic due to the explosive growth of video data. The motion features in a video are often used to detect events because an event may contain some specific actions or moving patterns. Raw motion features are extracted from the entire video first and then aggregated to form the final video representation. However, this video-based representation approach is ineffective when used for realistic videos because the video length can be very different and the clues for determining an event may happen in only a small segment of the entire video. In this paper, we propose using a segment-based approach for video representation. Basically, original videos are divided into segments for feature extraction and classification, while still keeping the evaluation at the video level. The experimental results on recent TRECVID Multimedia Event Detection datasets proved the effectiveness of our approach.     

基于兴趣度的Web用户聚类方法

现有的Web用户聚类方法都是通过对用户喜好页面的访问模式分析来建立用户聚类,没有充分考虑时间意识、用户兴趣、用户访问模式之间的关系与影响.针对这一问题,在时间意识的Web用户聚类基础之上,提出了基于兴趣度的Web用户聚类方法.通过对日志文件中的用户访问模式进行分析,计算用户兴趣度.结合渐进遗忘算法,对用户兴趣爱好进行调整与更新,并在此基础上对用户进行聚类.实验表明,本方法能够更好地分析用户访问模式,更准确地计算用户兴趣,具有更好的聚类效果.     

基于块特征的H.264压缩域对象分割

针对H.264压缩域,提出一种改进的运动对象分割方法。首先提取运动矢量场,对该矢量场进行矢量中值滤波,然后基于块进行前向矢量累积获得更加显著的矢量场,最后采用改进的K均值和EM的混合分层聚类方法,基于宏块层、块层两次聚类将运动对象分割出来。实验表明,该方法通过分层聚类,进一步提高了分割效率,能实现满足实时要求的较精确分割。     

Unsupervised multistage image classification using hierarchical clustering with a Bayesian similarity measure.

A new multistage method using hierarchical clustering for unsupervised image classification is presented. In the first phase, the multistage method performs segmentation using a hierarchical clustering procedure which confines merging to spatially adjacent clusters and generates an image partition such that no union of any neighboring segments has homogeneous intensity values. In the second phase, the segments resulting from the first stage are classified into a small number of distinct states by a sequential merging operation. The region-merging procedure in the first phase makes use of spatial contextual information by characterizing the geophysical connectedness of a digital image structure with a Markov random field, while the second phase employs a context-free similarity measure in the clustering process. The segmentation procedure of region merging is implemented as a hierarchical clustering algorithm whereby a multiwindow approach using a pyramid-like structure is employed to increase computational efficiency while maintaining spatial connectivity in merging. From experiments with both simulated and remotely sensed data, the proposed method was determined to be quite effective for unsupervised analysis. In particular, the region-merging approach based on spatial contextual information was shown to provide more accurate classification of images with smooth spatial patterns.     

Analysis of FMRI data using an integrated principal component analysis and supervised affinity propagation clustering approach

Clustering analysis is a promising data-driven method for analyzing functional magnetic resonance imaging (fMRI) time series data. The huge computational load, however, creates practical difficulties for this technique. We present a novel approach, integrating principal component analysis (PCA) and supervised affinity propagation clustering (SAPC). In this method, fMRI data are initially processed by PCA to obtain a preliminary image of brain activation. SAPC is then used to detect different brain functional activation patterns. We used a supervised Silhouette index to optimize clustering quality and automatically search for the optimal parameter p in SAPC, so that the basic affinity propagation clustering is improved by applying SAPC. Four simulation studies and tests with three in vivo fMRI datasets containing data from both block-design and event-related experiments revealed that functional brain activation was effectively detected and different response patterns were distinguished using our integrated method. In addition, the improved SAPC method was superior to the k -centers clustering and hierarchical clustering methods in both block-design and event-related fMRI data, as measured by the average squared error. These results suggest that our proposed novel integrated approach will be useful for detecting brain functional activation in both block-design and event-related experimental fMRI data.     

视频图像中雪花的检测和去除

以影响视频图像的自然界降雪雪花为研究对象.考虑到雪花在空间中随机分布和具有一定降落速度,并且目标或相机运动会给图像带来类似雪花运动的频率,用一种相关模型来捕获雪花的运动,用一种基于物理学的光度测定模型,从亮度角度描述雪花对图像的污染.基于这些模型,提出了一种检测和去除视频图像中雪花的DRS(detection and removal of snow)算法,并通过实验得到了验证.