Efficient Human Activity Recognition in Large Image and Video Databases

Vision-based human action recognition has attracted considerable interest in recent research for its applications to video surveillance, content-based search, healthcare, and interactive games. Most existing research deals with building informative feature descriptors, designing efficient and robust algorithms, proposing versatile and challenging datasets, and fusing multiple modalities. Often, these approaches build on certain conventions such as the use of motion cues to determine video descriptors, application of off-the-shelf classifiers, and single-factor classification of videos. In this thesis, we deal with important but overlooked issues such as efficiency, simplicity, and scalability of human activity recognition in different application scenarios: controlled video environment (e.g.~indoor surveillance), unconstrained videos (e.g.~YouTube), depth or skeletal data (e.g.~captured by Kinect), and person images (e.g.~Flicker). In particular, we are interested in answering questions like (a) is it possible to efficiently recognize human actions in controlled videos without temporal cues? (b) given that the large-scale unconstrained video data are often of high dimension low sample size (HDLSS) nature, how to efficiently recognize human actions in such data? (c) considering the rich 3D motion information available from depth or motion capture sensors, is it possible to recognize both the actions and the actors using only the motion dynamics of underlying activities? and (d) can motion information from monocular videos be used for automatically determining saliency regions for recognizing actions in still images

Architecture aware parallel programming in Glasgow parallel Haskell (GPH)

General purpose computing architectures are evolving quickly to become manycore and hierarchical: i.e. a core can communicate more quickly locally than globally. To be effective on such architectures, programming models must be aware of the communications hierarchy. This thesis investigates a programming model that aims to share the responsibility of task placement, load balance, thread creation, and synchronisation between the application developer and the runtime system. The main contribution of this thesis is the development of four new architectureaware constructs for Glasgow parallel Haskell that exploit information about task size and aim to reduce communication for small tasks, preserve data locality, or to distribute large units of work. We define a semantics for the constructs that specifies the sets of PEs that each construct identifies, and we check four properties of the semantics using QuickCheck. We report a preliminary investigation of architecture aware programming models that abstract over the new constructs. In particular, we propose architecture aware evaluation strategies and skeletons. We investigate three common paradigms, such as data parallelism, divide-and-conquer and nested parallelism, on hierarchical architectures with up to 224 cores. The results show that the architecture-aware programming model consistently delivers better speedup and scalability than existing constructs, together with a dramatic reduction in the execution time variability. We present a comparison of functional multicore technologies and it reports some of the first ever multicore results for the Feedback Directed Implicit Parallelism (FDIP) and the semi-explicit parallelism (GpH and Eden) languages. The comparison reflects the growing maturity of the field by systematically evaluating four parallel Haskell implementations on a common multicore architecture. The comparison contrasts the programming effort each language requires with the parallel performance delivered. We investigate the minimum thread granularity required to achieve satisfactory performance for three implementations parallel functional language on a multicore platform. The results show that GHC-GUM requires a larger thread granularity than Eden and GHC-SMP. The thread granularity rises as the number of cores rises

Reconstructing Human Motion

This thesis presents methods for reconstructing human motion in a variety of applications and begins with an introduction to the general motion capture hardware and processing pipeline. Then, a data-driven method for the completion of corrupted marker-based motion capture data is presented. The approach is especially suitable for challenging cases, e.g., if complete marker sets of multiple body parts are missing over a long period of time. Using a large motion capture database and without the need for extensive preprocessing the method is able to fix missing markers across different actors and motion styles. The approach can be used for incrementally increasing prior-databases, as the underlying search technique for similar motions scales well to huge databases. The resulting clean motion database could then be used in the next application: a generic data-driven method for recognizing human full body actions from live motion capture data originating from various sources. The method queries an annotated motion capture database for similar motion segments, able to handle temporal deviations from the original motion. The approach is online-capable, works in realtime, requires virtually no preprocessing and is shown to work with a variety of feature sets extracted from input data including positional data, sparse accelerometer signals, skeletons extracted from depth sensors and even video data. Evaluation is done by comparing against a frame-based Support Vector Machine approach on a freely available motion database as well as a database containing Judo referee signal motions. In the last part, a method to indirectly reconstruct the effects of the human heart's pumping motion from video data of the face is applied in the context of epileptic seizures. These episodes usually feature interesting heart rate patterns like a significant increase at seizure start as well as seizure-type dependent drop-offs near the end. The pulse detection method is evaluated for applicability regarding seizure detection in a multitude of scenarios, ranging from videos recorded in a controlled clinical environment to patient supplied videos of seizures filmed with smartphones

Subshifts with Simple Cellular Automata

A subshift is a set of infinite one- or two-way sequences over a fixed finite set, defined by a set of forbidden patterns. In this thesis, we study subshifts in the topological setting, where the natural morphisms between them are ones defined by a (spatially uniform) local rule. Endomorphisms of subshifts are called cellular automata, and we call the set of cellular automata on a subshift its endomorphism monoid. It is known that the set of all sequences (the full shift) allows cellular automata with complex dynamical and computational properties. We are interested in subshifts that do not support such cellular automata. In particular, we study countable subshifts, minimal subshifts and subshifts with additional universal algebraic structure that cellular automata need to respect, and investigate certain criteria of ‘simplicity’ of the endomorphism monoid, for each of them. In the case of countable subshifts, we concentrate on countable sofic shifts, that is, countable subshifts defined by a finite state automaton. We develop some general tools for studying cellular automata on such subshifts, and show that nilpotency and periodicity of cellular automata are decidable properties, and positive expansivity is impossible. Nevertheless, we also prove various undecidability results, by simulating counter machines with cellular automata. We prove that minimal subshifts generated by primitive Pisot substitutions only support virtually cyclic automorphism groups, and give an example of a Toeplitz subshift whose automorphism group is not finitely generated. In the algebraic setting, we study the centralizers of CA, and group and lattice homomorphic CA. In particular, we obtain results about centralizers of symbol permutations and bipermutive CA, and their connections with group structures.Siirretty Doriast

Context-aware learning for robot-assisted endovascular catheterization

Endovascular intervention has become a mainstream treatment of cardiovascular diseases. However, multiple challenges remain such as unwanted radiation exposures, limited two-dimensional image guidance, insufficient force perception and haptic cues. Fast evolving robot-assisted platforms improve the stability and accuracy of instrument manipulation. The master-slave system also removes radiation to the operator. However, the integration of robotic systems into the current surgical workflow is still debatable since repetitive, easy tasks have little value to be executed by the robotic teleoperation. Current systems offer very low autonomy, potential autonomous features could bring more benefits such as reduced cognitive workloads and human error, safer and more consistent instrument manipulation, ability to incorporate various medical imaging and sensing modalities. This research proposes frameworks for automated catheterisation with different machine learning-based algorithms, includes Learning-from-Demonstration, Reinforcement Learning, and Imitation Learning. Those frameworks focused on integrating context for tasks in the process of skill learning, hence achieving better adaptation to different situations and safer tool-tissue interactions. Furthermore, the autonomous feature was applied to next-generation, MR-safe robotic catheterisation platform. The results provide important insights into improving catheter navigation in the form of autonomous task planning, self-optimization with clinical relevant factors, and motivate the design of intelligent, intuitive, and collaborative robots under non-ionizing image modalities.Open Acces

Models for Learning (Mod4L) Final Report: Representing Learning Designs

The Mod4L Models of Practice project is part of the JISC-funded Design for Learning Programme. It ran from 1 May – 31 December 2006. The philosophy underlying the project was that a general split is evident in the e-learning community between development of e-learning tools, services and standards, and research into how teachers can use these most effectively, and is impeding uptake of new tools and methods by teachers. To help overcome this barrier and bridge the gap, a need is felt for practitioner-focused resources which describe a range of learning designs and offer guidance on how these may be chosen and applied, how they can support effective practice in design for learning, and how they can support the development of effective tools, standards and systems with a learning design capability (see, for example, Griffiths and Blat 2005, JISC 2006). Practice models, it was suggested, were such a resource. The aim of the project was to: develop a range of practice models that could be used by practitioners in real life contexts and have a high impact on improving teaching and learning practice. We worked with two definitions of practice models. Practice models are: 1. generic approaches to the structuring and orchestration of learning activities. They express elements of pedagogic principle and allow practitioners to make informed choices (JISC 2006) However, however effective a learning design may be, it can only be shared with others through a representation. The issue of representation of learning designs is, then, central to the concept of sharing and reuse at the heart of JISC’s Design for Learning programme. Thus practice models should be both representations of effective practice, and effective representations of practice. Hence we arrived at the project working definition of practice models as: 2. Common, but decontextualised, learning designs that are represented in a way that is usable by practitioners (teachers, managers, etc).(Mod4L working definition, Falconer & Littlejohn 2006). A learning design is defined as the outcome of the process of designing, planning and orchestrating learning activities as part of a learning session or programme (JISC 2006). Practice models have many potential uses: they describe a range of learning designs that are found to be effective, and offer guidance on their use; they support sharing, reuse and adaptation of learning designs by teachers, and also the development of tools, standards and systems for planning, editing and running the designs. The project took a practitioner-centred approach, working in close collaboration with a focus group of 12 teachers recruited across a range of disciplines and from both FE and HE. Focus group members are listed in Appendix 1. Information was gathered from the focus group through two face to face workshops, and through their contributions to discussions on the project wiki. This was supplemented by an activity at a JISC pedagogy experts meeting in October 2006, and a part workshop at ALT-C in September 2006. The project interim report of August 2006 contained the outcomes of the first workshop (Falconer and Littlejohn, 2006). The current report refines the discussion of issues of representing learning designs for sharing and reuse evidenced in the interim report and highlights problems with the concept of practice models (section 2), characterises the requirements teachers have of effective representations (section 3), evaluates a number of types of representation against these requirements (section 4), explores the more technically focused role of sequencing representations and controlled vocabularies (sections 5 & 6), documents some generic learning designs (section 8.2) and suggests ways forward for bridging the gap between teachers and developers (section 2.6). All quotations are taken from the Mod4L wiki unless otherwise stated

The structuring role of valence in the relationship between and within models of face and trait impressions

Tese apresentada para cumprimento dos requisitos necessários à obtenção do grau de Doutor em Psicologia na área de especialização de Psicologia Social, realizada sob a orientação de Teresa Garcia-Marques e coorientação de Leonel Garcia-Marques e Ron Dotsch, apresentada no ISPA - Instituto Universitário, no ano de 2019.In social face perception research, trustworthiness and dominance were found as the core dimensions underlying personality impressions based on facial appearance. These dimensions bear a striking resemblance to dimensions found in the parallel domain of person perception research such as the warmth and competence or communion and agency dimensions of personality impressions based on verbal person descriptions (e.g., trait-based descriptions). Given that both types of social information often co-occur in real social interactions and guide social decision making, it becomes crucial to understand how impressions derived from both sources are interrelated. Yet, so far, questions regarding the extent to which the dimensions of social face perception overlap with the dimensions of person perception, and regarding the nature and direction of the interrelationships between these dimensions, have been largely overlooked in the literature. The main goal of this thesis was to fill this gap in the literature and make initial steps towards the integration of social face perception and person perception models of personality impressions. In the first paper, a reverse correlation methodology was used to assess the extent to which dimensions of social face perception were perceived to overlap with dimensions of person perception by perceivers themselves. The results showed that dimensions establishing opposite relationships with valence, such as dominance and competence, were perceived as less similar than dimensions establishing a common positive relationship with valence, such as trustworthiness, warmth, and competence. These findings clarified that the dimensions of facial impressions and of person perception are not always perceived as redundant, and further highlighted the role of valence in shaping the relationship between dimensions across domains. The second paper employed a paradigm designed to directly assess the nature of the relationship that valence establishes with the core dimensions of social face perception and person perception. The results revealed that ability-related trait dimensions such as competence and dominance exhibited more variability in the nature and direction of their relationship with valence, comparatively to dimensions related with morality and warmth. These findings further emphasized that the overlap or dissociation between core dimensions of social judgment is largely driven by the features of the relationship they establish with valence. The third paper focused exclusively on social face perception and used a reverse correlation methodology to investigate how trustworthiness and dominance are naturally integrated into unitary impressions of facial appearance. The results showed that the dimension more strongly related with valence—trustworthiness—outweighed dominance in the resulting impressions of facial appearance. These findings highlight the primary role of valence information in shaping how dimensions are integrated within social face perception. Overall, these findings highlight the primary role of valence in structuring the relationship between dimensions of social judgment, not only across models of person perception and social face perception, but also within each model. Moreover, they offer a clearer picture on the relationship and integration of models of social face perception and person perception, and lay out clear new directions for future research on social perception in general.Na investigação em perceção social de faces, confiabilidade e dominância emergiram como as principais dimensões subjacentes às impressões de personalidade baseadas em aparência facial. Estas dimensões assemelham-se bastante às encontradas no domínio paralelo de perceção interpessoal, como as dimensões de simpatia e competência, ou communion e agência, que subjazem impressões de personalidade baseadas em descrições verbais de pessoas (e.g., baseadas em traços). Dada a coocorrência de ambos os tipos de informação na maioria de interações sociais reais, e o seu impacto na tomada de decisões sociais, torna-se crucial compreender como as impressões derivadas de ambas as fontes de informação se interrelacionam. Porém, o grau de sobreposição entre as dimensões da perceção social de faces e da perceção interpessoal, assim como a natureza e direção das inter-relações entre essas dimensões, têm sido questões amplamente negligenciadas na literatura. O principal objetivo desta tese foi preencher essa lacuna na literatura e dar os primeiros passos em direção à integração dos modelos de impressões de personalidade associados à perceção social de faces e à perceção interpessoal. No primeiro artigo, métodos de reverse correlation foram implementados para avaliar em que medida as dimensões da perceção social da face se sobrepõem às dimensões da perceção interpessoal na perspetiva dos próprios percipientes. Os resultados mostraram que as dimensões exibindo relações opostas com valência, como dominância e competência, foram percebidas como menos semelhantes entre si comparativamente às dimensões partilhando a mesma relação (positiva) com a valência, como confiabilidade, simpatia, e competência. Estes achados esclareceram que as dimensões de impressões faciais e da perceção interpessoal nem sempre são percebidas como redundantes, e destacam o papel da valência na estruturação das relações das dimensões entre os dois domínios de investigação. No segundo artigo, desenvolveu-se um paradigma para avaliar diretamente a natureza da relação que a valência estabelece com as dimensões centrais das impressões faciais e da perceção interpessoal. Os resultados revelaram que as dimensões de traço relacionadas com habilidade, como competência e dominância, exibiram maior variabilidade na natureza e direção da sua relação com valência, comparativamente às dimensões relacionadas com moralidade e simpatia. Estes achados enfatizaram ainda que a sobreposição, ou dissociação, entre as dimensões é amplamente promovida pelas características das relações destas com valência. O terceiro artigo focou-se exclusivamente na perceção social de faces, e utilizou métodos de reverse correlation para investigar como a confiabilidade e a dominância são naturalmente integradas em impressões unitárias de aparência facial. Os resultados mostraram que a dimensão mais fortemente relacionada com valência—confiabilidade—teve maior peso que dominância nas impressões faciais. Estes achados destacam o papel primário da valência na integração de dimensões em impressões faciais. No geral, estes achados destacam o papel primário da valência na estruturação das relações entre dimensões de julgamento social, não apenas entre os modelos de impressões faciais e de perceção interpessoal, mas também dentro de cada modelo. Além disso, oferecem uma visão mais clara sobre a relação e integração destes modelos, e traçam direções claras para futuras investigações no domínio geral da perceção social.Fundação para a Ciência e a Tecnologia - FC

LIPIcs, Volume 248, ISAAC 2022, Complete Volume

LIPIcs, Volume 248, ISAAC 2022, Complete Volum

Good Men Grow Corn: Embodied Ecological Heritage in a Belizean Mopan Community

Recent developments in land rights and land use in the Toledo district, Belize has generated anthropological and activist interest surrounding traditional ecological knowledge and practice, and the role of heritage in communities. This study explores the connection between ecological knowledge and practices, and the concurrent construction of heritage, and community health and wellness, broadly defined. Developing and using the concept of “embodied ecological heritage,” this dissertation takes a phenomenological approach to understanding the convergence of ecological heritage and health in multiple realms of everyday life, arguing that lived experience of participating in “traditional”practices is fundamentally connected to wellness in the Mopan community of Santa Cruz. Using the results of ethnographic research using multiple methodologies across 76 households over a period of 11 months, this dissertation presents a detailed account of how Mopan Maya participants view ecological skill and knowledge as critical to being and living well, arguing that social factors, such as work and food choices, have an effect on wellness. The research contributes to a growing number of studies linking changes in the body and overall health status to everyday practices within communities. Outlining how certain knowledge and particular practices, such as exchanging labor and making baskets, become prioritized as heritage through both their conceptualization and deployment, the analysis centers on individual bodies as the foci of skill, sensory experience and change. The timely nature of making these connections explicit is discussed in light of ongoing “development” in Maya communities and beyond, with an illumination of how changing land use patterns have far-reaching effects on wellness from multiple perspectives; individual, social, ecological and political, and concluding that a consideration of wellness can benefit from looking at the processes involved in heritage construction as it relates to ecological practice