Feeling crowded yet?: Crowd simulations for VR

With advances in virtual reality technology and its multiple applications, the need for believable, immersive virtual environments is increasing. Even though current computer graphics methods allow us to develop highly realistic virtual worlds, the main element failing to enhance presence is autonomous groups of human inhabitants. A great number of crowd simulation techniques have emerged in the last decade, but critical details in the crowd's movements and appearance do not meet the standards necessary to convince VR participants that they are present in a real crowd. In this paper, we review recent advances in the creation of immersive virtual crowds and discuss areas that require further work to turn these simulations into more fully immersive and believable experiences.Peer ReviewedPostprint (author's final draft

Hierarchical path-finding for Navigation Meshes (HNA*)

Path-finding can become an important bottleneck as both the size of the virtual environments and the number of agents navigating them increase. It is important to develop techniques that can be efficiently applied to any environment independently of its abstract representation. In this paper we present a hierarchical NavMesh representation to speed up path-finding. Hierarchical path-finding (HPA*) has been successfully applied to regular grids, but there is a need to extend the benefits of this method to polygonal navigation meshes. As opposed to regular grids, navigation meshes offer representations with higher accuracy regarding the underlying geometry, while containing a smaller number of cells. Therefore, we present a bottom-up method to create a hierarchical representation based on a multilevel k-way partitioning algorithm (MLkP), annotated with sub-paths that can be accessed online by our Hierarchical NavMesh Path-finding algorithm (HNA*). The algorithm benefits from searching in graphs with a much smaller number of cells, thus performing up to 7.7 times faster than traditional A¿ over the initial NavMesh. We present results of HNA* over a variety of scenarios and discuss the benefits of the algorithm together with areas for improvement.Peer ReviewedPostprint (author's final draft

Delincuencia, personalidad y psicopatología

Ambientalismos (sociológicos y psicológicos) y endogenismos psicológicos y biológicos son incapaces de explicar de forma satisfactoria la delincuencia violenta. Asimismo los modelos constitucionalistas y los temperamentales ignoran la diversidad y versatilidad aparejada con la delincuencia criminal. Se revisa, además (a) la idea de psicopatía y sus diversificaciones, así como sus relaciones con los trastornos de personalidad (DSM): la conclusión es que ni la psicopatía ni los trastornos de personalidad tal y como son presentados en la ctualidad ofrecen mucho más que una presentación general demasiado rígida y/o inespecífica como para generar, desde ellas programas de intervención y (b) las tareas y acciones principales del psicólogo en el sistema penal-judicial. Desde el modelo de parámetros se insiste en los factores contextual-motivacionales y cognitivos que ofrecen una personalidadtanto de diagnóstico como de intervención en adolescentes y adultos, con ilustración de resultados.___________________________Radical environmental models (from sociology and from psychology) like that endogenous psychological models are considered of a low value in the scientific analysis of criminal behaviour. The concepts of (a) psychopathy and of the personality disorders are revised in order to achieve a psychological and psychopathological picture of criminal behaviour; and (b) the main tasks and possibilities of the psychologist in the justice system are also revised. Both concepts and the tasks revised have some serious problems for an accuracy description, explanation and psychological interventions in criminal behaviour. One different line of research is proposed, from the parameter model, based on the motivational-contextual factors of personality and the interpersonal skills, interpreted as dimensions capable of be trained, inclusive in institutions for criminal people. Some implications on the future of violence people in contemporary society are remembered and a possible forecast on the relative frequency of criminal behaviour among young people in the next future is proposed

A survey of real-time crowd rendering

In this survey we review, classify and compare existing approaches for real-time crowd rendering. We first overview character animation techniques, as they are highly tied to crowd rendering performance, and then we analyze the state of the art in crowd rendering. We discuss different representations for level-of-detail (LoD) rendering of animated characters, including polygon-based, point-based, and image-based techniques, and review different criteria for runtime LoD selection. Besides LoD approaches, we review classic acceleration schemes, such as frustum culling and occlusion culling, and describe how they can be adapted to handle crowds of animated characters. We also discuss specific acceleration techniques for crowd rendering, such as primitive pseudo-instancing, palette skinning, and dynamic key-pose caching, which benefit from current graphics hardware. We also address other factors affecting performance and realism of crowds such as lighting, shadowing, clothing and variability. Finally we provide an exhaustive comparison of the most relevant approaches in the field.Peer ReviewedPostprint (author's final draft

Intervención psicológica en enfermos crónicos : sentido común y sabiduría popular

Se presentan doce afirmaciones básicas sobre la manera de vivir y entender la enfermedad crónica, asentadas en el sentido común, en la experiencia del autor y en la sabiduría popular encarnada en los refranes. Los temas generales son: (1) Identidad personal y enfermedad; (2) aceptación y realismo; (3) relación positiva con el cuerpo y los síntomas; (4) la significación de “cambio” y la necesidad por “dejar pasar”; (5) la aceptación de sí mismo/a y el perdón;(6) La necesidad de relacionarse con los demás; (7) realidad y realismo frente a culpa e inculpación; (8) tenemos hábitos y no todos los que tenemos son buenos; (9) aprender a identificar las recompensas; (10) búsqueda de independencia, no de individualismo egoísta; (11) apertura física, mental y social y (12) mantenimiento de sosiego y de paz interior. Cada afirmación resume un conjunto de estrategias y técnicas de intervención (módulos de intervención) y se utilizan los refranes como ilustración y material de ejercicios a realizar fuera de las sesiones. Se trata de un programa puesto a prueba por partes y que puede funcionar tanto en su integridad como en módulos independientes. Se aplica a nivel individual o en pequeño grupo de enfermos. Se sugiere una sesión semanal de duración entre 45 y 90 minutos.12 basic sentences based on common sense are the ground of this psychological intervention program in chronic illness: (1) personal identity and disease; (2) acceptance and realism; (3) positive relationship with the body and the symptomatology; (4) the meaning of “change” and the necessity of “let by”; (5) self-acceptance and forgiveness; (6) the need for interpersonal relationships; (7) reality and realism in front of to blame for the disease; (8) we must know our habits and not all of them are good for the health and subjective well-being; (9) to learn to identify the rewards; (10) the search for autonomy, but not of selfish individualism; (11) social, mental and physical openness; and (12) the maintenance of peacefulness and calm. Each statement contains a set of the main techniques to achieve it, relative independent among themselves. The sayings are used as exercise material in sessions and inter- sessions. This program has been used in renal diseases hospitalized and can to be applied individually and in group. On suggests one weekly session (45-90 minutes)

Exploring virtual reality as a validation methodology

Virtual environments can be used as a test bed for validation of human behavior simulation techniques since they place people within a simulated situation from an egocentric perspective. We propose level of presence achieved by a human in a virtual environment (VE) as a metric for virtual crowd behavior. Using experimental evidence from the presence literature and the results of a pilot experiment that we ran, we explore the egocentric features that a crowd simulation model should have in order to achieve high levels of presence.Postprint (author’s final draft

Comparison of crowd simulation for building evacuation and an alternative approach

This paper presents an overview of crowd simulation models, their limitations, and an alternative agent-based approch. First we introduce several methods and then we focus on two widely used and validated simulation tools that use grid-based models. We discus the artifacts that these models introduce regarding the way they treat the space and the implication that this has in the movement of the agents during the simulation. We also describe the limitations that current commercial software tools have in terms of simulating human psychology and physiology. The paper discusses an agent-based alternative approach developed to overcome these limitations. The model allows for the simulation of human movement that can provide results more closely describing behavior of real people during an emergency situation. Flow rates, densities and speeds emerge in our model from the physical interactions between people instead of being predefined.Postprint (published version

Facing uncertainty in web service compositions

© 2013 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works[EN] Web service compositions run in complex computing infrastructures where arising events may affect the quality of the system. However, crucial Web service compositions cannot be stopped to apply changes to deal with problematic events. Therefore, the trend is moving towards context-aware Web service compositions, which use context information as a basis for autonomic changes. Under the closed-world assumption, the context and possible adaptations are fully known at design time. Nevertheless, it is difficult to foresee all the possible situations arising in uncertain contexts. In this paper, we leverage models at runtime to guide the dynamic evolution of context-aware Web service compositions to deal with unexpected events in the open world. In order to manage uncertainty, a model that abstracts the Web service composition, self-evolves to preserve requirements. The evolved model guides changes in the underlying WS-BPEL composition schema. A prototype and an evaluation demonstrate the feasibility of our approach.This work has been developed with the support of MICINN under the project everyWare TIN2010-18011 and co-financed with ERDF.Alférez, GH.; Pelechano Ferragud, V. (2013). Facing uncertainty in web service compositions. En Web Services (ICWS), 2013 IEEE 20th International Conference on. IEEE Computer Society. 219-226. https://doi.org/10.1109/ICWS.2013.38S21922

An automatic tool to facilitate authoring animation blending in game engines

Achieving realistic virtual humans is crucial in virtual reality applications and video games. Nowadays there are software and game development tools, that are of great help to generate and simulate characters. They offer easy to use GUIs to create characters by dragging and drooping features, and making small modifications. Similarly, there are tools to create animation graphs and setting blending parameters among others. Unfortunately, even though these tools are relatively user friendly, achieving natural animation transitions is not straight forward and thus non-expert users tend to spend a large amount of time to generate animations that are not completely free of artefacts. In this paper we present a method to automatically generate animation blend spaces in Unreal engine, which offers two advantages: the first one is that it provides a tool to evaluate the quality of an animation set, and the second one is that the resulting graph does not depend on user skills and it is thus not prone to user errors.Peer ReviewedPostprint (author's final draft

Towards the Composition of Services by End-Users

Nowadays, we live surrounded by heterogeneous and distributed services that are available to people anytime and anywhere. Even though these services can be used individually, it is through their synchronized and combined usage that end-users are provided with added value. However, existing solutions to service composition are not targeted at ordinary end-users. In fact, these solutions require technical knowledge to deal with the technological heterogeneity in which they are offered to the market. To this end, the paper presents a tool-supported platform that is aided by: (1) EUCalipTool, an end-user mobile tool that implements a Domain Specific Visual Language, which has been specifically designed to compose services on mobile devices; (2) a Faceted Service Registry, which plays the role of gateway between service implementations and end-users, hiding technological issues from the latter when including services in a composition; and (3) a Generation Module, which transforms end-user descriptions into BPMN specification that are interpreted by an execution infrastructure developed for that purpose