Real-time action recognition using a multilayer descriptor with variable size

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Video analysis technology has become less expensive and more powerful in terms of storage resources and resolution capacity, promoting progress in a wide range of applications. Video-based human action detection has been used for several tasks in surveillance environments, such as forensic investigation, patient monitoring, medical training, accident prevention, and traffic monitoring, among others. We present a method for action identification based on adaptive training of a multilayer descriptor applied to a single classifier. Cumulative motion shapes (CMSs) are extracted according to the number of frames present in the video. Each CMS is employed as a self-sufficient layer in the training stage but belongs to the same descriptor. A robust classification is achieved through individual responses of classifiers for each layer, and the dominant result is used as a final outcome. Experiments are conducted on five public datasets (Weizmann, KTH, MuHAVi, IXMAS, and URADL) to demonstrate the effectiveness of the method in terms of accuracy in real time. (C) 2016 SPIE and IS&TVideo analysis technology has become less expensive and more powerful in terms of storage resources and resolution capacity, promoting progress in a wide range of applications. Video-based human action detection has been used for several tasks in surveill2501FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)SEM INFORMAÇÃOSEM INFORMAÇÃ

RGB-D-based Action Recognition Datasets: A Survey

Human action recognition from RGB-D (Red, Green, Blue and Depth) data has attracted increasing attention since the first work reported in 2010. Over this period, many benchmark datasets have been created to facilitate the development and evaluation of new algorithms. This raises the question of which dataset to select and how to use it in providing a fair and objective comparative evaluation against state-of-the-art methods. To address this issue, this paper provides a comprehensive review of the most commonly used action recognition related RGB-D video datasets, including 27 single-view datasets, 10 multi-view datasets, and 7 multi-person datasets. The detailed information and analysis of these datasets is a useful resource in guiding insightful selection of datasets for future research. In addition, the issues with current algorithm evaluation vis-\'{a}-vis limitations of the available datasets and evaluation protocols are also highlighted; resulting in a number of recommendations for collection of new datasets and use of evaluation protocols

A PYRAMIDAL APPROACH FOR DESIGNING DEEP NEURAL NETWORK ARCHITECTURES

Developing an intelligent system, capable of learning discriminative high-level features from high dimensional data lies at the core of solving many computer vision (CV ) and machine learning (ML) tasks. Scene or human action recognition from videos is an important topic in CV and ML. Its applications include video surveillance, robotics, human-computer interaction, video retrieval, etc. Several bio inspired hand crafted feature extraction systems have been proposed for processing temporal data. However, recent deep learning techniques have dominated CV and ML by their good performance on large scale datasets. One of the most widely used deep learning technique is Convolutional neural network (CNN) or its variations, e.g. ConvNet, 3DCNN, C3D. CNN kernel scheme reduces the number of parameters with respect to fully connected Neural Networks. Recent deep CNNs have more layers and more kernels for each layer with respect to early CNNs, and as a consequence, they result in a large number of parameters. In addition, they violate the pyramidal plausible architecture of biological neural network due to the increasing number of filters at each higher layer resulting in difficulty for convergence at training step. In this dissertation, we address three main questions central to pyramidal structure and deep neural networks: 1) Is it worth to utilize pyramidal architecture for proposing a generalized recognition system? 2) How to enhance pyramidal neural network (PyraNet) for recognizing action and dynamic scenes in the videos? 3) What will be the impact of imposing pyramidal structure on a deep CNN? In the first part of the thesis, we provide a brief review of the work done for action and dynamic scene recognition using traditional computer vision and machine learning approaches. In addition, we give a historical and present overview of pyramidal neural networks and how deep learning emerged. In the second part, we introduce a strictly pyramidal deep architecture for dynamic scene and human action recognition. It is based on the 3DCNN model and the image pyramid concept. We introduce a new 3D weighting scheme that presents a simple connection scheme with lower computational and memory costs and results in less number of learnable parameters compared to other neural networks. 3DPyraNet extracts features from both spatial and temporal dimensions by keeping biological structure, thereby it is capable to capture the motion information encoded in multiple adjacent frames. 3DPyraNet model is extended with three modifications: 1) changing input image size; 2) changing receptive field and overlap size in correlation layers; and 3) adding a linear classifier at the end to classify the learned features. It results in a discriminative approach for spatiotemporal feature learning in action and dynamic scene recognition. In combination with a linear SVM classifier, our model outperforms state-of-the-art methods in one-vs-all accuracy on three video benchmark datasets (KTH, Weizmann, and Maryland). Whereas, it gives competitive accuracy on a 4th dataset (YUPENN). In the last part of our thesis, we investigate to what extent CNN may take advantage of pyramid structure typical of biological neurons. A generalized statement over convolutional layers from input up-to fully connected layer is introduced that further helps in understanding and designing a successful deep network. It reduces ambiguity, number of parameters, and their size on disk without degrading overall accuracy. It also helps in giving a generalize guideline for modeling a deep architecture by keeping certain ratio of filters in starting layers vs. other deeper layers. Competitive results are achieved compared to similar well-engineered deeper architectures on four benchmark datasets. The same approach is further applied on person re-identification. Less ambiguity in features increase Rank-1 performance and results in better or comparable results to the state-of-the-art deep models