A virtual environment to simulate the experience of psychosis

Psychosis is a mental disorder that affects 1-2% of the population at some point in their lives. One of the main causes of psychosis is the mental illness schizophrenia. Sufferers of this illness often have terrifying symptoms such as hallucinations, delusions, and thought disorder. This project aims to develop a virtual environment to simulate the experience of psychosis, focusing on re-creating auditory and visual hallucinations. A model of a psychiatric ward was created and the psychosis simulation software was written to re-create the auditory and visual hallucinations of one particular patient. The patient was very impressed with the simulation, and commented that it effectively re-created the same emotions that she experienced on a day-to-day basis during her psychotic episodes. It is hoped that this work will result in a useful educational tool about schizophrenia, leading to improved training of clinicians, and fostering improved understanding and empathy toward sufferers of schizophrenia in the community, ultimately improving the quality of life and chances of recovery of patients.

co-creativepen toolkit: a pen-based 3d toolkit for children cooperatly designing virtual environment

Co-CreativePen Toolkit is a pen-based 3D toolkit for children cooperatly designing virtual environment. This toolkit is used to construct different applications involved with distributedpen-based 3D interaction. In this toolkit,sketch method is encapsulated as kinds of interaction techniques. Children can use pen to construct 3D and IBR objects, to navigate in the virtual world, to select and manipulate virtual objects, and to communicate with other children. Children can use pen to select other children in the virtual world, and use pen to write message to children selected The distributed architecture of Co-CreativePen Toolkit is based on the CORBA. A common scene graph is managed in the server with several copies of this graph are managed in every client.Every changes of the scene graph in client will cause the change in the server and other client.

Echtzeitsimulation großer Grafikmodelle

Die vorliegende Arbeit entstand während meiner Zeit als wissenschaftlicher Mitarbeiter im Fachgebiet Technische Informatik an der Universität Kassel. Im Rahmen dieser Arbeit werden der Entwurf und die Implementierung eines Cluster-basierten verteilten Szenengraphen gezeigt. Bei der Implementierung des verteilten Szenengraphen wurde von der Entwicklung eines eigenen Szenengraphen abgesehen. Stattdessen wurde ein bereits vorhandener Szenengraph namens OpenSceneGraph als Basis für die Entwicklung des verteilten Szenengraphen verwendet. Im Rahmen dieser Arbeit wurde eine Clusterunterstützung in den vorliegenden OpenSceneGraph integriert. Bei der Erweiterung des OpenSceneGraphs wurde besonders darauf geachtet den vorliegenden Szenengraphen möglichst nicht zu verändern. Zusätzlich wurde nach Möglichkeit auf die Verwendung und Integration externer Clusterbasierten Softwarepakete verzichtet. Für die Verteilung des OpenSceneGraphs wurde auf Basis von Sockets eine eigene Kommunikationsschicht entwickelt und in den OpenSceneGraph integriert. Diese Kommunikationsschicht wurde verwendet um Sort-First- und Sort-Last-basierte Visualisierung dem OpenSceneGraph zur Verfügung zu stellen. Durch die Erweiterung des OpenScenGraphs um die Cluster-Unterstützung wurde eine Ansteuerung beliebiger Projektionssysteme wie z.B. einer CAVE ermöglicht. Für die Ansteuerung einer CAVE wurden mittels VRPN diverse Eingabegeräte sowie das Tracking in den OpenSceneGraph integriert. Durch die Anbindung der Geräte über VRPN können diese Eingabegeräte auch bei den anderen Cluster-Betriebsarten wie z.B. einer segmentierten Anzeige verwendet werden. Die Verteilung der Daten auf den Cluster wurde von dem Kern des OpenSceneGraphs separat gehalten. Damit kann eine beliebige OpenSceneGraph-basierte Anwendung jederzeit und ohne aufwendige Modifikationen auf einem Cluster ausgeführt werden. Dadurch ist der Anwender in seiner Applikationsentwicklung nicht behindert worden und muss nicht zwischen Cluster-basierten und Standalone-Anwendungen unterscheiden.

Metodología para la generación automática de entornos virtuales en simuladores de conducción terrestre

Está Tesis refleja los trabajos de investigación que tienen como resultado el desarrollo de una metodología cuyo objetivo es la automatización optimizada en la generación de grandes entornos virtuales destinados a simulaciones de conducción terrestre guiada, es decir, sobre trayectorias predefinidas, bajo PC. En ella se aborda el ciclo completo de generación de un entorno virtual, aportando soluciones optimizadas en cada una de las fases. Para definir estas soluciones, se ha llevado a cabo un estudio en profundidad de las características y requisitos exigidos a este tipo de representaciones virtuales así como de las posibles vías resolutivas, concluyéndose con el establecimiento de tres fases constructivas. La primera fase es la del análisis perceptivo visual. La presente Tesis, tras sintetizar las características que definen a este tipo de entornos así como sus condiciones perceptivas, propone una metodología constructiva que saca el máximo partido de las mismas de una manera hasta ahora no considerada: la creación del entorno mediante el ensamblaje y repetición (instanciación) de un número finito de patrones repetitivos o módulos. Son múltiples las ventajas aportadas por este sistema modular de instanciación: disminución de las labores de modelado, reducción drástica de la memoria de almacenamiento requerida y de los tiempos de carga, facilitación de las tareas de creación y edición de los escenarios. La segunda fase es la generación geométrica y topológica del entorno. El elevado volumen y heterogeneidad de la información a manejar hace necesario el desarrollo de métodos que automaticen el procesamiento de la misma. La presente Tesis desarrolla un sistema consistente en varios criterios de organización, corrección y almacenamiento de la información de partida. Dicho sistema permite por un lado la construcción fácilmente escalable y editable de entornos que cumplan las normativas circulatorias vigentes y por otro lado garantiza un óptimo flujo de la información entre los diversos subsistemas integrantes de la simulación. Flujo que ha sido plasmado en la elaboración de diversos protocolos de comunicación. La tercera fase es la del posicionamiento 3D de la base de datos visual, su jerarquización y optimización escénica. En esta fase, la presente Tesis ha desarrollado una serie de Algoritmos de Posicionamiento modular que garantizan el correcto acoplamiento de los módulos a lo largo de una serie de líneas directrices. Dichas líneas son creadas a partir de la definición de las trayectorias circulatorias, lo que ha permitido a su vez, la definición por parte de esta Tesis de un sistema de niveles de detalle discretos pseudo-variantes con el punto de vista, que permite optimizar la carga geométrica del escenario, mediante la definición en tiempo de precarga de los posibles niveles de detalle de cada módulo en función de su distancia transversal a la trayectoria. Por otro lado, con el fin de potenciar las ventajas de este sistema de instanciación esta Tesis propone el empleo de una serie de shaders que deforman los módulos en tiempo real, lo que permite disminuir el número de módulos necesarios en tiempo de precarga y aumenta la versatilidad constructiva y realismo de los escenarios. Finalmente, esta Tesis organiza todo el escenario en un grafo de la escena (scene graph) que busca minimizar el recorrido del mismo con el fin de maximizar las velocidades de refresco y facilitar las labores de edición de los escenarios. En este punto, la construcción modular del entorno es fundamental para alcanzar dichos objetivos. Todos los planteamientos teóricos expuestos en esta Tesis se han materializado en las correspondientes aplicaciones informáticas que se han validado como herramientas de desarrollo en la creación de grandes entornos virtuales de simuladores actualmente en funcionamiento, como los de Metro de Madrid de las series 7000, 8000, 3000, 9000 y Citadis y en otros experimentales donde también se han implementado los criterios y resultados perceptivos que optimizan estos simuladores.

Uma estratégia para otimizar a geração de arranjos em subestações virtuais de energia elétrica

The Virtual Reality techniques applied in Electricity Environments provide a new supervisory control paradigm. The fact of existing a virtual environment (VE), geometrically similar to a real substation, reduces the difference of mental models built by field operators compared with those built by system center operation improving the communication. Beside this, those systems can be used as visualization interfaces for electricity system simulators, training systems for professors and undergraduate students, field operators and maintenance professionals. However, the development process of these systems is quite complex, combining several activities such as implementation, 3D modeling, virtual sceneries construction, usability assessment and management project techniques. In this context, this work present a GUI strategy to build field arrangements based on scene graphs, to reduce time in Virtual Electricity Substations Arrangement development. Through this, mistakes during the VE building can be avoided making this process more reliable. As an concept proof, all toolkits developed in this work were applied in the virtualization of the substations from a Brazilian power concessionary named CEMIG.

Development of a semantic graph-based scene description

Software representations of scenes, i.e. the modelling of objects in space, are used in many application domains. Current modelling and scene description standards focus on visualisation dimensions, and are intrinsically limited by their dependence upon their semantic interpretation and contextual application by humans. In this paper we propose the need for an open, extensible and semantically rich modelling language, which facilitates a machine-readable semantic structure. We critically review existing standards and techniques, and highlight a need for a semantically focussed scene description language. Based on this defined need we propose a preliminary solution, based on hypergraph theory, and reflect on application domains.

Fuzzy Connectedness Image Segmentation in Graph Cut Formulation: A Linear-Time Algorithm and a Comparative Analysis

A deep theoretical analysis of the graph cut image segmentation framework presented in this paper simultaneously translates into important contributions in several directions. The most important practical contribution of this work is a full theoretical description, and implementation, of a novel powerful segmentation algorithm, GC(max). The output of GC(max) coincides with a version of a segmentation algorithm known as Iterative Relative Fuzzy Connectedness, IRFC. However, GC(max) is considerably faster than the classic IRFC algorithm, which we prove theoretically and show experimentally. Specifically, we prove that, in the worst case scenario, the GC(max) algorithm runs in linear time with respect to the variable M=|C|+|Z|, where |C| is the image scene size and |Z| is the size of the allowable range, Z, of the associated weight/affinity function. For most implementations, Z is identical to the set of allowable image intensity values, and its size can be treated as small with respect to |C|, meaning that O(M)=O(|C|). In such a situation, GC(max) runs in linear time with respect to the image size |C|. We show that the output of GC(max) constitutes a solution of a graph cut energy minimization problem, in which the energy is defined as the a"" (a) norm ayenF (P) ayen(a) of the map F (P) that associates, with every element e from the boundary of an object P, its weight w(e). This formulation brings IRFC algorithms to the realm of the graph cut energy minimizers, with energy functions ayenF (P) ayen (q) for qa[1,a]. Of these, the best known minimization problem is for the energy ayenF (P) ayen(1), which is solved by the classic min-cut/max-flow algorithm, referred to often as the Graph Cut algorithm. We notice that a minimization problem for ayenF (P) ayen (q) , qa[1,a), is identical to that for ayenF (P) ayen(1), when the original weight function w is replaced by w (q) . Thus, any algorithm GC(sum) solving the ayenF (P) ayen(1) minimization problem, solves also one for ayenF (P) ayen (q) with qa[1,a), so just two algorithms, GC(sum) and GC(max), are enough to solve all ayenF (P) ayen (q) -minimization problems. We also show that, for any fixed weight assignment, the solutions of the ayenF (P) ayen (q) -minimization problems converge to a solution of the ayenF (P) ayen(a)-minimization problem (ayenF (P) ayen(a)=lim (q -> a)ayenF (P) ayen (q) is not enough to deduce that). An experimental comparison of the performance of GC(max) and GC(sum) algorithms is included. This concentrates on comparing the actual (as opposed to provable worst scenario) algorithms' running time, as well as the influence of the choice of the seeds on the output.

High level methods for scene exploration

Virtual worlds exploration techniques are used in a wide variety of domains — from graph drawing to robot motion. This paper is dedicated to virtual world exploration techniques which have to help a human being to understand a 3D scene. An improved method of viewpoint quality estimation is presented in the paper, together with a new off-line method for automatic 3D scene exploration, based on a virtual camera. The automatic exploration method is working in two steps. In the first step, a set of “good” viewpoints is computed. The second step uses this set of points of view to compute a camera path around the scene. Finally, we define a notion of semantic distance between objects of the scene to improve the approach.

Building the View Graph of a Category by Exploiting Image Realism

We propose a weakly supervised method to arrange images of a given category based on the relative pose between the camera and the object in the scene. Relative poses are points on a sphere centered at the object in a given canonical pose, which we call object viewpoints. Our method builds a graph on this sphere by assigning images with similar viewpoint to the same node and by connecting nodes if they are related by a small rotation. The key idea is to exploit a large unlabeled dataset to validate the likelihood of dominant 3D planes of the object geometry. A number of 3D plane hypotheses are evaluated by applying small 3D rotations to each hypothesis and by measuring how well the deformed images match other images in the dataset. Correct hypotheses will result in deformed images that correspond to plausible views of the object, and thus will likely match well other images in the same category. The identified 3D planes are then used to compute affinities between images related by a change of viewpoint. We then use the affinities to build a view graph via a greedy method and the maximum spanning tree.

Topological SLAM using a graph-matching based method on omnidirectional images

Comunicación presentada en el XI Workshop of Physical Agents, Valencia, 9-10 septiembre 2010.

A stable graph-based representation for object recognition through high-order matching

Many Object recognition techniques perform some flavour of point pattern matching between a model and a scene. Such points are usually selected through a feature detection algorithm that is robust to a class of image transformations and a suitable descriptor is computed over them in order to get a reliable matching. Moreover, some approaches take an additional step by casting the correspondence problem into a matching between graphs defined over feature points. The motivation is that the relational model would add more discriminative power, however the overall effectiveness strongly depends on the ability to build a graph that is stable with respect to both changes in the object appearance and spatial distribution of interest points. In fact, widely used graph-based representations, have shown to suffer some limitations, especially with respect to changes in the Euclidean organization of the feature points. In this paper we introduce a technique to build relational structures over corner points that does not depend on the spatial distribution of the features. © 2012 ICPR Org Committee.

Supervised learning of graph structure

Graph-based representations have been used with considerable success in computer vision in the abstraction and recognition of object shape and scene structure. Despite this, the methodology available for learning structural representations from sets of training examples is relatively limited. In this paper we take a simple yet effective Bayesian approach to attributed graph learning. We present a naïve node-observation model, where we make the important assumption that the observation of each node and each edge is independent of the others, then we propose an EM-like approach to learn a mixture of these models and a Minimum Message Length criterion for components selection. Moreover, in order to avoid the bias that could arise with a single estimation of the node correspondences, we decide to estimate the sampling probability over all the possible matches. Finally we show the utility of the proposed approach on popular computer vision tasks such as 2D and 3D shape recognition. © 2011 Springer-Verlag.

Gesturing elsewhere: the identity politics of the Balinese death/thrash metal scene

This essay explores the political significance of Balinese death/thrash fandom. In the early 1990s, the emergence of a death/thrash scene in Bali paralleled growing criticism of accelerated tourism development on the island. Specifically, locals protested the increasing ubiquity of Jakarta, 'the centre', cast as threatening to an authentically 'low', peripheral Balinese culture. Similarly, death/thrash enthusiasts also gravitated toward certain fringes, although they rejected dominant notions of Balinese-ness by gesturing elsewhere, toward a global scene. The essay explores the ways in which death/thrash enthusiasts engaged with local discourses by coveting their marginality, and aims to demonstrate how their articulations of 'alien-ness' contributed in important ways to a broader regionalism.