Human Action Recognition Based on Temporal Pyramid of Key Poses Using RGB-D Sensors

Human action recognition is a hot research topic in computer vision, mainly due to the high number of related applications, such as surveillance, human computer interaction, or assisted living. Low cost RGB-D sensors have been extensively used in this field. They can provide skeleton joints, which represent a compact and effective representation of the human posture. This work proposes an algorithm for human action recognition where the features are computed from skeleton joints. A sequence of skeleton features is represented as a set of key poses, from which histograms are extracted. The temporal structure of the sequence is kept using a temporal pyramid of key poses. Finally, a multi-class SVM performs the classification task. The algorithm optimization through evolutionary computation allows to reach results comparable to the state-of-the-art on the MSR Action3D dataset.This work was supported by a STSM Grant from COST Action IC1303 AAPELE - Architectures, Algorithms and Platforms for Enhanced Living Environments

Human Action Recognition with RGB-D Sensors

none3noHuman action recognition, also known as HAR, is at the foundation of many different applications related to behavioral analysis, surveillance, and safety, thus it has been a very active research area in the last years. The release of inexpensive RGB-D sensors fostered researchers working in this field because depth data simplify the processing of visual data that could be otherwise difficult using classic RGB devices. Furthermore, the availability of depth data allows to implement solutions that are unobtrusive and privacy preserving with respect to classic video-based analysis. In this scenario, the aim of this chapter is to review the most salient techniques for HAR based on depth signal processing, providing some details on a specific method based on temporal pyramid of key poses, evaluated on the well-known MSR Action3D dataset.Cippitelli, Enea; Gambi, Ennio; Spinsante, SusannaCippitelli, Enea; Gambi, Ennio; Spinsante, Susann

Human Action Recognition with RGB-D Sensors

Human action recognition, also known as HAR, is at the foundation of many different applications related to behavioral analysis, surveillance, and safety, thus it has been a very active research area in the last years. The release of inexpensive RGB-D sensors fostered researchers working in this field because depth data simplify the processing of visual data that could be otherwise difficult using classic RGB devices. Furthermore, the availability of depth data allows to implement solutions that are unobtrusive and privacy preserving with respect to classic video-based analysis. In this scenario, the aim of this chapter is to review the most salient techniques for HAR based on depth signal processing, providing some details on a specific method based on temporal pyramid of key poses, evaluated on the well-known MSR Action3D dataset

Design of Complex Engineered Systems Using Multiagent Coordination

This thesis is the combination of two research publications working toward a unified strategy in which the design of complex engineered systems can be completed using a multiagent coordination approach. Current engineered system modeling techniques segment large complex models into multiple groups to be simulated independently. These methods restrict the evaluations of such complex systems, as their failure properties are typically unknown until they are experienced in operation. In an effort to help engineers to design complex engineered systems, this research proposes that a distributed yet non-legislated approach can be used in the design processes by splitting up the overall system into specific teams. The approach specifically hypothesizes that multiagent credit assignment can be used to effectively determine how to properly incentivize subsystem designers so that the global set of system-level objectives can be achieved. The first publication presents a multiagent systems based approach for designing a self-replicating robotic manufacturing factory in space. The simulation in this work is able to present the coordination of the agents during the construction of the factory as the parameters of the learning algorithm are changed. The results show the advantage of using a learning algorithm to design a large system. The second publication presents a hybrid approach to design complex engineered systems, providing a method in which design decisions can be reconciled without the need for either detailed interaction models or external legislating mechanisms. The results of this paper demonstrate that a team of autonomous agents using a cooperative coevolutionary algorithm can effectively design a complex engineered system. Each publication utilized a system model to illustrate and simulate the methods and potential results. By designing complex systems with a multiagent coordination approach, a design methodology can be developed in an effort to reduce design uncertainty and provide mechanisms through which the system level impact of decisions can be estimated without explicitly modeling such interactions

Coevolutionary algorithms for the optimization of strategies for red teaming applications

Red teaming (RT) is a process that assists an organization in finding vulnerabilities in a system whereby the organization itself takes on the role of an “attacker” to test the system. It is used in various domains including military operations. Traditionally, it is a manual process with some obvious weaknesses: it is expensive, time-consuming, and limited from the perspective of humans “thinking inside the box”. Automated RT is an approach that has the potential to overcome these weaknesses. In this approach both the red team (enemy forces) and blue team (friendly forces) are modelled as intelligent agents in a multi-agent system and the idea is to run many computer simulations, pitting the plan of the red team against the plan of blue team. This research project investigated techniques that can support automated red teaming by conducting a systematic study involving a genetic algorithm (GA), a basic coevolutionary algorithm and three variants of the coevolutionary algorithm. An initial pilot study involving the GA showed some limitations, as GAs only support the optimization of a single population at a time against a fixed strategy. However, in red teaming it is not sufficient to consider just one, or even a few, opponent‟s strategies as, in reality, each team needs to adjust their strategy to account for different strategies that competing teams may utilize at different points. Coevolutionary algorithms (CEAs) were identified as suitable algorithms which were capable of optimizing two teams simultaneously for red teaming. The subsequent investigation of CEAs examined their performance in addressing the characteristics of red teaming problems, such as intransitivity relationships and multimodality, before employing them to optimize two red teaming scenarios. A number of measures were used to evaluate the performance of CEAs and in terms of multimodality, this study introduced a novel n-peak problem and a new performance measure based on the Circular Earth Movers‟ Distance. Results from the investigations involving an intransitive number problem, multimodal problem and two red teaming scenarios showed that in terms of the performance measures used, there is not a single algorithm that consistently outperforms the others across the four test problems. Applications of CEAs on the red teaming scenarios showed that all four variants produced interesting evolved strategies at the end of the optimization process, as well as providing evidence of the potential of CEAs in their future application in red teaming. The developed techniques can potentially be used for red teaming in military operations or analysis for protection of critical infrastructure. The benefits include the modelling of more realistic interactions between the teams, the ability to anticipate and to counteract potentially new types of attacks as well as providing a cost effective solution

Human action recognition and mobility assessment in smart environments with RGB-D sensors

openQuesta attività di ricerca è focalizzata sullo sviluppo di algoritmi e soluzioni per ambienti intelligenti sfruttando sensori RGB e di profondità. In particolare, gli argomenti affrontati fanno riferimento alla valutazione della mobilità di un soggetto e al riconoscimento di azioni umane. Riguardo il primo tema, l'obiettivo è quello di implementare algoritmi per l'estrazione di parametri oggettivi che possano supportare la valutazione di test di mobilità svolta da personale sanitario. Il primo algoritmo proposto riguarda l'estrazione di sei joints sul piano sagittale utilizzando i dati di profondità forniti dal sensore Kinect. La precisione in termini di stima degli angoli di busto e ginocchio nella fase di sit-to-stand viene valutata considerando come riferimento un sistema stereofotogrammetrico basato su marker. Un secondo algoritmo viene proposto per facilitare la realizzazione del test in ambiente domestico e per consentire l'estrazione di un maggior numero di parametri dall'esecuzione del test Timed Up and Go. I dati di Kinect vengono combinati con quelli di un accelerometro attraverso un algoritmo di sincronizzazione, costituendo un setup che può essere utilizzato anche per altre applicazioni che possono beneficiare dell'utilizzo congiunto di dati RGB, profondità ed inerziali. Vengono quindi proposti algoritmi di rilevazione della caduta che sfruttano la stessa configurazione del Timed Up and Go test. Per quanto riguarda il secondo argomento affrontato, l'obiettivo è quello di effettuare la classificazione di azioni che possono essere compiute dalla persona all'interno di un ambiente domestico. Vengono quindi proposti due algoritmi di riconoscimento attività i quali utilizzano i joints dello scheletro di Kinect e sfruttano un SVM multiclasse per il riconoscimento di azioni appartenenti a dataset pubblicamente disponibili, raggiungendo risultati confrontabili con lo stato dell'arte rispetto ai dataset CAD-60, KARD, MSR Action3D.This research activity is focused on the development of algorithms and solutions for smart environments exploiting RGB and depth sensors. In particular, the addressed topics refer to mobility assessment of a subject and to human action recognition. Regarding the first topic, the goal is to implement algorithms for the extraction of objective parameters that can support the assessment of mobility tests performed by healthcare staff. The first proposed algorithm regards the extraction of six joints on the sagittal plane using depth data provided by Kinect sensor. The accuracy in terms of estimation of torso and knee angles in the sit-to-stand phase is evaluated considering a marker-based stereometric system as a reference. A second algorithm is proposed to simplify the test implementation in home environment and to allow the extraction of a greater number of parameters from the execution of the Timed Up and Go test. Kinect data are combined with those of an accelerometer through a synchronization algorithm constituting a setup that can be used also for other applications that benefit from the joint usage of RGB, depth and inertial data. Fall detection algorithms exploiting the same configuration of the Timed Up and Go test are therefore proposed. Regarding the second topic addressed, the goal is to perform the classification of human actions that can be carried out in home environment. Two algorithms for human action recognition are therefore proposed, which exploit skeleton joints of Kinect and a multi-class SVM for the recognition of actions belonging to publicly available datasets, achieving results comparable with the state of the art in the datasets CAD-60, KARD, MSR Action3D.INGEGNERIA DELL'INFORMAZIONECippitelli, EneaCippitelli, Ene