Unions of Onions: Preprocessing Imprecise Points for Fast Onion Decomposition

Let $\mathcal{D}$ be a set of $n$ pairwise disjoint unit disks in the plane. We describe how to build a data structure for $\mathcal{D}$ so that for any point set $P$ containing exactly one point from each disk, we can quickly find the onion decomposition (convex layers) of $P$. Our data structure can be built in $O(n \log n)$ time and has linear size. Given $P$, we can find its onion decomposition in $O(n \log k)$ time, where $k$ is the number of layers. We also provide a matching lower bound. Our solution is based on a recursive space decomposition, combined with a fast algorithm to compute the union of two disjoint onionComment: 10 pages, 5 figures; a preliminary version appeared at WADS 201

Automatic Landmarking for Non-cooperative 3D Face Recognition

This thesis describes a new framework for 3D surface landmarking and evaluates its performance for feature localisation on human faces. This framework has two main parts that can be designed and optimised independently. The first one is a keypoint detection system that returns positions of interest for a given mesh surface by using a learnt dictionary of local shapes. The second one is a labelling system, using model fitting approaches that establish a one-to-one correspondence between the set of unlabelled input points and a learnt representation of the class of object to detect. Our keypoint detection system returns local maxima over score maps that are generated from an arbitrarily large set of local shape descriptors. The distributions of these descriptors (scalars or histograms) are learnt for known landmark positions on a training dataset in order to generate a model. The similarity between the input descriptor value for a given vertex and a model shape is used as a descriptor-related score. Our labelling system can make use of both hypergraph matching techniques and rigid registration techniques to reduce the ambiguity attached to unlabelled input keypoints for which a list of model landmark candidates have been seeded. The soft matching techniques use multi-attributed hyperedges to reduce ambiguity, while the registration techniques use scale-adapted rigid transformation computed from 3 or more points in order to obtain one-to-one correspondences. Our final system achieves better or comparable (depending on the metric) results than the state-of-the-art while being more generic. It does not require pre-processing such as cropping, spike removal and hole filling and is more robust to occlusion of salient local regions, such as those near the nose tip and inner eye corners. It is also fully pose invariant and can be used with kinds of objects other than faces, provided that labelled training data is available

Perceptually Driven Simulation

This dissertation describes, implements and analyzes a comprehensive system for perceptually-driven virtual reality simulation, based on algorithms which dynamically adjust level of detail (LOD) for entity simulation in order to maximize simulation realism as perceived by the viewer. First we review related work in simulation LOD, and describe the weaknesses of the analogy that has traditionally been drawn between simulation LOD and graphical LOD. We describe the process of perceptual criticality modeling for quantitatively estimating the relative importance of different entities in maintaining perceived realism and predicting the consequences of LOD transitions on perceived realism. We present heuristic cognitive models of human perception, memory, and attention to perform this modeling. We then propose the LOD Trader , a framework for perceptually driven LOD selection and an online approximation algorithm for efficiently identifying useful LOD transitions. We then describe alibi generation , a method of retroactively elaborating a human agent\u27s behavior to maintain its realism under prolonged scrutiny from the viewer, and discuss its integration into a heterogeneous perceptually driven simulation. We then present the Marketplace simulation system and describe how perceptually driven simulation techniques were used to maximize perceived realism, and evaluate their success in doing so. Finally, we summarize the dissertation work performed and its expected contributions to real-time modeling and simulation environments

Morphometric Analysis of Variation in Human Proximal Long Bones Within and Between Populations

Morphological variation and reactivity in human bone underpins many research questions in palaeopathology, osteoarchaeology, and anthropology. Studies on the post-crania primarily pertain to the cross-sectional geometry and epiphyseal or joint morphology and diaphyseal curvature. Very few studies address diaphyseal surface morphology. This study aims to quantify morphology of the epiphyses, diaphyseal surface morphology, and cross-sectional morphology of human proximal long bones in relation to interpopulation and intrapopulation variables including sex, age, childhood stress indicators, and pathology. To provide some diversity in geography and temporality this research uses skeletons selected from the English medieval cemeteries of St. Guthlac’s Priory, Hereford and Fishergate House, York, the Sudanese medieval cemetery 3-J-18 from Mis Island, and the English postmedieval cemetery Coach Lane, North Shields. Cross-sectional geometry was collected via digital sectioning of 3D scans and morphological information was collected using Geometric Morphometrics. The resulting morphological and geometric sets were compared against inter and intrapopulation variables and qualitatively compared to each other to determine which limb and what part of its proximal bone is most reactive to given variables. Morphological variation with intra and interpopulation variables was found, and its expression varied with size, age, population, bone, and morphological or geometric set. Age and morphology vary together in both epiphyseal and diaphyseal morphology, but do not appear as related in values for cross—sectional geometry. Likewise stress indicators do vary with the morphology of the diaphysis or epiphyses but the strength of their relationship often relies on the population sampled. This suggests a wealth of impact on morphology from environment, ontogenetic trajectory and development, population affinity, health, sex, life history, and age. This research highlights variation in reactivity in different anatomical areas. Crucially, this research demonstrates the morphological plasticity of the diaphyseal surface which for some variables was very reactive and is presently largely unexamined

Cometary Escape in the Restricted Circular Planar Three Body Problem

The classical principle of least action says that orbits of mechanical systems extremize action; an important subclass are those orbits that minimize action. This principle is utilized along with Aubry-Mather theory to construct regions of instability for a certain three body problem, given by a Hamiltonian system of two degrees of freedom. In principle, these methods can be applied to construct instability regions for a variety of Hamiltonian systems with $2$ degrees of freedom. The Hamiltonian model considered in this thesis describes the dynamics of a Sun-Jupiter-Comet system and under some simplifying assumptions, the existence of instabilities for the orbit of the comet is shown. In particular it is shown that a comet which starts close to an orbit in the shape of an ellipse of eccentricity $e=0.66$ can increase in eccentricity to beyond $e=1$. Furthermore, there exist ejection orbits for the comet. Such orbits are initially well within the range of our solar system. This might give an indication of why most objects rotating around the Sun in our solar system have relatively low eccentricity. Several new theoretical tools are introduced in this thesis as well. The most notable is a checkable sufficient condition to verify that an exact area preserving map is an exact area preserving twist map in a certain coordinate system. This coordinate system is constructed by ``spreading the cumulative twist'' which arises from the long term dynamics of system. Many of the results of the thesis are `computer assisted' and utilize recent advances in rigorous numerical integration. It is through the application of these advances in computing that it has become possible to state deep results for realistic solar systems. This has been the dream of many since humans first observed the stars so long ago

Viral Loads

Drawing upon the empirical scholarship and research expertise of contributors from all settled continents and from diverse life settings and economies, Viral Loads illustrates how the COVID-19 pandemic, and responses to it, lay bare and load onto people’s lived realities in countries around the world. A crosscutting theme pertains to how social unevenness and gross economic disparities are shaping global and local responses to the pandemic, and illustrate the effects of both the virus and efforts to contain it in ways that amplify these inequalities. At the same time, the contributions highlight the nature of contemporary social life, including virtual communication, the nature of communities, neoliberalism and contemporary political economies, and the shifting nature of nation states and the role of government. Over half of the world’s population has been affected by restrictions of movement, with physical distancing requirements and self-isolation recommendations impacting profoundly on everyday life but also on the economy, resulting also, in turn, with dramatic shifts in the economy and in mass unemployment. By reflecting on how the pandemic has interrupted daily lives, state infrastructures and healthcare systems, the contributing authors in this volume mobilise anthropological theories and concepts to locate the pandemic in a highly connected and exceedingly unequal world. The book is ambitious in its scope – spanning the entire globe – and daring in its insistence that medical anthropology must be a part of the growing calls to build a new world

Proceedings of the 11th International Conference on Kinanthropology

The 11th International Conference on Kinantropology was held on the Nov 29 – Dec 1, 2017 in Brno and was organized by the Faculty of Sports Studies, Masaryk University and the Faculty of Kinesiology, University of Zagreb. This year was divided into several themes: sports medicine, sport and social science, sport training, healthy lifestyle and healthy ageing, sports management, analysis of human movement. Part of the conference was also a symposium Atletika and Ortoreha that gathered specialists in physiotherapy