EM-Based Mixture Models Applied to Video Event Detection
  Surveillance system (SS) development requires hi-tech support to prevail over the shortcomings related to the massive quantity of visual information from SSs. Anything but reduced human monitoring became impossible by means of its physical and economic implications, and an advance towards an automated surveillance becomes the only way out. When it comes to a computer vision system, automatic video event comprehension is a challenging task due to motion clutter, event understanding under complex scenes, multilevel semantic event inference, contextualization of events and views obtained from multiple cameras, unevenness of motion scales, shape changes, occlusions and object interactions among lots of other impairments. In recent years, state-of-the-art models for video event classification and recognition include modeling events to discern context, detecting incidents with only one camera, low-level feature extraction and description, high-level semantic event classification, and recognition. Even so, it is still very burdensome to recuperate or label a specific video part relying solely on its content. Principal component analysis (PCA) has been widely known and used, but when combined with other techniques such as the expectation-maximization (EM) algorithm its computation becomes more efficient. This chapter introduces advances associated with the concept of Probabilistic PCA (PPCA) analysis of video event and it also aims at looking closely to ways and metrics to evaluate these less intensive EM implementations of PCA and KPCA. 
Alessandra Martins Coelho, Vania V. Estrela
cs.CV