Proceedings of the 10th International Conference on Computer Graphics Theory and Applications (GRAPP'15)

This book contains the proceedings of the 10th International Conference on Computer Graphics Theory and Applications (GRAPP 2015) which was organized and sponsored by the Institute for Systems and Technologies of Information, Control and Communication (INSTICC), in cooperation with ACM SIGGRAPH and technically co-sponsored by IEEE Computer Society, IEEE VGTC and IEEE Technical Committee on Multimedia Computing. The proceedings here published, demonstrate new and innovative solutions, and highlight technical problems in each field that are challenging and worthwhile. GRAPP 2015 was organized to promote a discussion forum between researchers, developers, manufactures and end-users, about the conferences research topics and to establish guidelines in the development of more advanced solutions. We received a high number of paper submissions for this edition of GRAPP, 93 in total, with contributions from all five continents which attest to the success and global dimension of GRAPP. To evaluate each submission, we used a double-blind evaluation method and each paper was reviewed by at least three experts. At least three experts were from the International Program Committee. Among them the Primary expert was in charge of leading a discussion together with all the reviewers of the papers in order to propose an initial recommendation to the Area chairs and Program Chairs. The Area Chairs and Program Chairs made the final selection. In the end, 16 papers were selected for publication as full papers; 16 papers were accepted for short presentation and 28 were accepted for poster presentation. The result was an oral-paper acceptance ratio of 34% and a high-quality program that is attractive to experts from the Computer Graphics area. We hope that these Conference Proceedings, submitted for indexation by Thomson Reuters Conference Proceedings Citation Index, INSPEC, DBLP and EI, may help the Computer Graphics community to find Inspiring research work. Furthermore, a short list of presented papers will be selected to be expanded into a forthcoming book of VISIGRAPP Selected Papers to be published by Springer during 2015 in the CCIS series. All papers presented at this conference will be available at the SCITEPRESS Digital Library. The conference schedule included a Doctoral Consortium which will certainly provide an opportunity for graduate students to explore their research interests in an interdisciplinary workshop, under the guidance of a panel of distinguished experts in the field. Moreover, we are proud to inform that the program also includes four plenary keynote lectures, given by internationally distinguished researchers, namely Andrea Cavallaro (Queen Mary University of London, United Kingdom), Daniel Thalmann (Nanyang Technological University, Singapore), Gerik Scheuermann (Universtät Leipzig, Germany) and Mauro Barni (Universita` di Siena, Italy), thus contributing to increase the overall quality of the conference and to provide a deeper understanding of the conference interest fields. Finally, we would like to express our thanks, first of all, to the authors of the technical papers, whose work and dedication made possible to put together a program that we believe very exciting and of high technical quality. Next, we would like to thank all the members of the program committee and auxiliary reviewers, who helped us with their expertise and time. The area chairs namely Roland Geraerts, Arjan Egges, Tobias Ritschel and Jérôme Grosjean, had a crucial and most essential role in the conference and therefore they also deserve a big thank you. We would also like to thank the invited speakers for their invaluable contribution and for sharing their vision in their talks. Special thanks should be addressed to the INSTICC Steering Committee, and organizing team whose invaluable work made possible this event. We wish you all an exciting conference and an unforgettable stay in Berlin, Germany. We hope to meet you again for the next edition of GRAPP, details of which are available at http://www.grapp.visigrapp.org

Two-way multi-lane traffic model for pedestrians in corridors

We extend the Aw-Rascle macroscopic model of car traffic into a two-way multi-lane model of pedestrian traffic. Within this model, we propose a technique for the handling of the congestion constraint, i.e. the fact that the pedestrian density cannot exceed a maximal density corresponding to contact between pedestrians. In a first step, we propose a singularly perturbed pressure relation which models the fact that the pedestrian velocity is considerably reduced, if not blocked, at congestion. In a second step, we carry over the singular limit into the model and show that abrupt transitions between compressible flow (in the uncongested regions) to incompressible flow (in congested regions) occur. We also investigate the hyperbolicity of the two-way models and show that they can lose their hyperbolicity in some cases. We study a diffusive correction of these models and discuss the characteristic time and length scales of the instability

Traffic Instabilities in Self-Organized Pedestrian Crowds

In human crowds as well as in many animal societies, local interactions among individuals often give rise to self-organized collective organizations that offer functional benefits to the group. For instance, flows of pedestrians moving in opposite directions spontaneously segregate into lanes of uniform walking directions. This phenomenon is often referred to as a smart collective pattern, as it increases the traffic efficiency with no need of external control. However, the functional benefits of this emergent organization have never been experimentally measured, and the underlying behavioral mechanisms are poorly understood. In this work, we have studied this phenomenon under controlled laboratory conditions. We found that the traffic segregation exhibits structural instabilities characterized by the alternation of organized and disorganized states, where the lifetime of well-organized clusters of pedestrians follow a stretched exponential relaxation process. Further analysis show that the inter-pedestrian variability of comfortable walking speeds is a key variable at the origin of the observed traffic perturbations. We show that the collective benefit of the emerging pattern is maximized when all pedestrians walk at the average speed of the group. In practice, however, local interactions between slow- and fast-walking pedestrians trigger global breakdowns of organization, which reduce the collective and the individual payoff provided by the traffic segregation. This work is a step ahead toward the understanding of traffic self-organization in crowds, which turns out to be modulated by complex behavioral mechanisms that do not always maximize the group's benefits. The quantitative understanding of crowd behaviors opens the way for designing bottom-up management strategies bound to promote the emergence of efficient collective behaviors in crowds.Comment: Article published in PLoS Computational biology. Freely available here: http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.100244

A hierarchy of heuristic-based models of crowd dynamics

International audienceWe derive a hierarchy of kinetic and macroscopic models from a noisy variant of the heuristic behavioral Individual-Based Model of Moussaid et al, PNAS 2011, where the pedestrians are supposed to have constant speeds. This IBM supposes that the pedestrians seek the best compromise between navigation towards their target and collisions avoidance. We first propose a kinetic model for the probability distribution function of the pedestrians. Then, we derive fluid models and propose three different closure relations. The first two closures assume that the velocity distribution functions are either a Dirac delta or a von Mises-Fisher distribution respectively. The third closure results from a hydrodynamic limit associated to a Local Thermodynamical Equilibrium. We develop an analogy between this equilibrium and Nash equilibia in a game theoretic framework. In each case, we discuss the features of the models and their suitability for practical use

Modeling, Evaluation, and Scale on Artificial Pedestrians: A Literature Review

Modeling pedestrian dynamics and their implementation in a computer are challenging and important issues in the knowledge areas of transportation and computer simulation. The aim of this article is to provide a bibliographic outlook so that the reader may have quick access to the most relevant works related to this problem. We have used three main axes to organize the article's contents: pedestrian models, validation techniques, and multiscale approaches. The backbone of this work is the classification of existing pedestrian models; we have organized the works in the literature under five categories, according to the techniques used for implementing the operational level in each pedestrian model. Then the main existing validation methods, oriented to evaluate the behavioral quality of the simulation systems, are reviewed. Furthermore, we review the key issues that arise when facing multiscale pedestrian modeling, where we first focus on the behavioral scale (combinations of micro and macro pedestrian models) and second on the scale size (from individuals to crowds). The article begins by introducing the main characteristics of walking dynamics and its analysis tools and concludes with a discussion about the contributions that different knowledge fields can make in the near future to this exciting area

The Involvement of SMILE/TMTC3 in Endoplasmic Reticulum Stress Response

The state of operational tolerance has been detected sporadically in some renal transplanted patients that stopped immunosuppressive drugs, demonstrating that allograft tolerance might exist in humans. Several years ago, a study by Brouard et al. identified a molecular signature of several genes that were significantly differentially expressed in the blood of such patients compared with patients with other clinical situations. The aim of the present study is to analyze the role of one of these molecules over-expressed in the blood of operationally tolerant patients, SMILE or TMTC3, a protein whose function is still unknown.We first confirmed that SMILE mRNA is differentially expressed in the blood of operationally tolerant patients with drug-free long term graft function compared to stable and rejecting patients. Using a yeast two-hybrid approach and a colocalization study by confocal microscopy we furthermore report an interaction of SMILE with PDIA3, a molecule resident in the endoplasmic reticulum (ER). In accordance with this observation, SMILE silencing in HeLa cells correlated with the modulation of several transcripts involved in proteolysis and a decrease in proteasome activity. Finally, SMILE silencing increased HeLa cell sensitivity to the proteasome inhibitor Bortezomib, a drug that induces ER stress via protein overload, and increased transcript expression of a stress response protein, XBP-1, in HeLa cells and keratinocytes.In this study we showed that SMILE is involved in the endoplasmic reticulum stress response, by modulating proteasome activity and XBP-1 transcript expression. This function of SMILE may influence immune cell behavior in the context of transplantation, and the analysis of endoplasmic reticulum stress in transplantation may reveal new pathways of regulation in long-term graft acceptance thereby increasing our understanding of tolerance

Climatology of the three coastal Antarctic stations Dumont D'urville, Neumayer and Halley

Long term air and snowfall chemistry measurements have beenperformed at the three coastal Antarctic stations Dumont dÚrville(66°40ŽS, 140°1ŽE), Neumayer (70°39ŽS, 8°15ŽW), and Halley(75°35ŽS, 26°19ŽW). The results have to be interpreted andcompared with respect to the regional meteorological conditions.In this study the 3-hourly synoptic surface observations taken at thethree stations between 1991 and 1995, as well as the dailyupper air soundings from 1993, are analyzed to describe theaspects of station climatologies relevant for the air and snowfall chemistrymeasurements discussed in the papers of this special section. Although the threestations are comparable, being situated close to the coastline of Antarctica, themeteorological conditions differ. While at Dumont dŽUrville katabatic winds causeprediminant strong and relatively dry surface winds from the interior of Antarctica,Neumayer and Halley are frequently influenced by easterly winds associated mostlywith eastwardmoving cyclones. From April through October the wind field above 5 km isgoverned by a circumpolar vortex with westerly winds increasing with height.Dumont dÚrville represents a station at the edge of this vortexwith extreme stratospheric wind velocities above 50 m/s. Neumayer and Halley aremostly situated within the vortex and isolated from airmasses advecting fromlower latitudes into the upper troposphere and lower stratosphere during theAustral winter