A Framework for Dynamic Terrain with Application in Off-road Ground Vehicle Simulations

The dissertation develops a framework for the visualization of dynamic terrains for use in interactive real-time 3D systems. Terrain visualization techniques may be classified as either static or dynamic. Static terrain solutions simulate rigid surface types exclusively; whereas dynamic solutions can also represent non-rigid surfaces. Systems that employ a static terrain approach lack realism due to their rigid nature. Disregarding the accurate representation of terrain surface interaction is rationalized because of the inherent difficulties associated with providing runtime dynamism. Nonetheless, dynamic terrain systems are a more correct solution because they allow the terrain database to be modified at run-time for the purpose of deforming the surface. Many established techniques in terrain visualization rely on invalid assumptions and weak computational models that hinder the use of dynamic terrain. Moreover, many existing techniques do not exploit the capabilities offered by current computer hardware. In this research, we present a component framework for terrain visualization that is useful in research, entertainment, and simulation systems. In addition, we present a novel method for deforming the terrain that can be used in real-time, interactive systems. The development of a component framework unifies disparate works under a single architecture. The high-level nature of the framework makes it flexible and adaptable for developing a variety of systems, independent of the static or dynamic nature of the solution. Currently, there are only a handful of documented deformation techniques and, in particular, none make explicit use of graphics hardware. The approach developed by this research offloads extra work to the graphics processing unit; in an effort to alleviate the overhead associated with deforming the terrain. Off-road ground vehicle simulation is used as an application domain to demonstrate the practical nature of the framework and the deformation technique. In order to realistically simulate terrain surface interactivity with the vehicle, the solution balances visual fidelity and speed. Accurately depicting terrain surface interactivity in off-road ground vehicle simulations improves visual realism; thereby, increasing the significance and worth of the application. Systems in academia, government, and commercial institutes can make use of the research findings to achieve the real-time display of interactive terrain surfaces

Approach to deformable terrain visualization and a soil behaviour model

The objective of this work was to research and develop the visualisation of deformable terrain and a soil behaviour model in a real-time 3D simulation software. This work was done as a part of Mevea software development project, which covered the design and implementation of a deformable terrain extension to Mevea simulation software. This work discusses the initial design of the terrain extension and addresses the problems that were discovered during the design and implementation process. The resulting document discusses the problems of deformable terrain visualisation and presents an approach that was used in the implementation of Mevea simulation software

Real-time transition texture synthesis for terrains.

Depicting the transitions where differing material textures meet on a terrain surface presents a particularly unique set of challenges in the field of real-time rendering. Natural landscapes are inherently irregular and composed of complex interactions between many different material types of effectively endless detail and variation. Although consumer grade graphics hardware is becoming ever increasingly powerful with each successive generation, terrain texturing remains a trade-off between realism and the computational resources available. Technological constraints aside, there is still the challenge of generating the texture resources to represent terrain surfaces which can often span many hundreds or even thousands of square kilometres. To produce such textures by hand is often impractical when operating on a restricted budget of time and funding. This thesis presents two novel algorithms for generating texture transitions in realtime using automated processes. The first algorithm, Feature-Based Probability Blending (FBPB), automates the task of generating transitions between material textures containing salient features. As such features protrude through the terrain surface FBPB ensures that the topography of these features is maintained at transitions in a realistic manner. The transitions themselves are generated using a probabilistic process that also dynamically adds wear and tear to introduce high frequency detail and irregularity at the transition contour. The second algorithm, Dynamic Patch Transitions (DPT), extends FBPB by applying the probabilistic transition approach to material textures that contain no salient features. By breaking up texture space into a series of layered patches that are either rendered or discarded on a probabilistic basis, the contour of the transition is greatly increased in resolution and irregularity. When used in conjunction with high frequency detail techniques, such as alpha masking, DPT is capable of producing endless, detailed, irregular transitions without the need for artistic input

Simulation et rendu temps-réel de nuages convectifs à l'échelle du paysage

This paper presents an efficient, physics-based procedural model for the real-time animation andvisualization of cumulus clouds at landscape size.We couple a coarse Lagrangian model of air parcels with a proceduralamplification using volumetric noise.Our Lagrangian model draws an aerology \ie the atmospheric physicsof hydrostatic atmosphere with thermodynamics transforms,augmented by a model of mixing between parcels and environment.In addition to the particle-particle interactions, we introduce particle-implicit environmentinteractions. In contrast to the usual fluid simulation, we thus do not needto sample the transparent environment, a key property forreal-time efficiency and scalability to large domains.Inheriting from the high-level physics of aerology, we also validate oursimulation by comparing it to predictive diagrams, and we show how the user caneasily control key aspects of the result such as the cloud base andtop altitude. Our model is thus fast, physical and controllable.Cet article présente un modèle temps-réel procédural basé sur laphysique pour l'animation et la visualisation temps réel de cumulus à l'échelle du paysage. Nous couplons un modèle Lagrangien basse-résolution de parcelles atmosphériques avec un modèle d'amplification procédurale à base de bruit volumique.Notre modèle Lagrangien s'appuie sur l'aérologie \ie la physique de l'atmosphère en équilibre hydrostatique avec transformations thermodynamiques,augmentée d'un modèle de mélange entre les parcelles et de l'environnement.En plus des interactions entre particules, nous introduisons lesinteractions entre les particules et l'environnement implicites. Contrairement à la simulation de fluides habituel, on n'a donc pas besoin d'échantillonner l'environnement transparent, une propriété clé pourl'accessibilité au temps réel et la scalabilité aux grandes étendues.Héritant de la physique à haut niveau de l'aérologie, nous validons notresimulation en la comparant aux diagrammes prédictifs, et nous montrons comment l'utilisateur peutcontrôler facilement les principaux aspects du résultat commel'altitude de la base et du haut des nuages. Notre modèle est donc rapide, physique et contrôlable

PolyVR - A Virtual Reality Authoring Framework for Engineering Applications

Die virtuelle Realität ist ein fantastischer Ort, frei von Einschränkungen und vielen Möglichkeiten. Für Ingenieure ist dies der perfekte Ort, um Wissenschaft und Technik zu erleben, es fehlt jedoch die Infrastruktur, um die virtuelle Realität zugänglich zu machen, insbesondere für technische Anwendungen. Diese Arbeit bescheibt die Entstehung einer Softwareumgebung, die eine einfachere Entwicklung von Virtual-Reality-Anwendungen und deren Implementierung in immersiven Hardware-Setups ermöglicht. Virtual Engineering, die Verwendung virtueller Umgebungen für Design-Reviews während des Produktentwicklungsprozesses, wird insbesondere von kleinen und mittleren Unternehmen nur äußerst selten eingesetzt. Die Hauptgründe sind nicht mehr die hohen Kosten für professionelle Virtual-Reality-Hardware, sondern das Fehlen automatisierter Virtualisierungsabläufe und die hohen Wartungs- und Softwareentwicklungskosten. Ein wichtiger Aspekt bei der Automatisierung von Virtualisierung ist die Integration von Intelligenz in künstlichen Umgebungen. Ontologien sind die Grundlage des menschlichen Verstehens und der Intelligenz. Die Kategorisierung unseres Universums in Begriffe, Eigenschaften und Regeln ist ein grundlegender Schritt von Prozessen wie Beobachtung, Lernen oder Wissen. Diese Arbeit zielt darauf ab, einen Schritt zu einem breiteren Einsatz von Virtual-Reality-Anwendungen in allen Bereichen der Wissenschaft und Technik zu entwickeln. Der Ansatz ist der Aufbau eines Virtual-Reality-Authoring-Tools, eines Softwarepakets zur Vereinfachung der Erstellung von virtuellen Welten und der Implementierung dieser Welten in fortschrittlichen immersiven Hardware-Umgebungen wie verteilten Visualisierungssystemen. Ein weiteres Ziel dieser Arbeit ist es, das intuitive Authoring von semantischen Elementen in virtuellen Welten zu ermöglichen. Dies sollte die Erstellung von virtuellen Inhalten und die Interaktionsmöglichkeiten revolutionieren. Intelligente immersive Umgebungen sind der Schlüssel, um das Lernen und Trainieren in virtuellen Welten zu fördern, Prozesse zu planen und zu überwachen oder den Weg für völlig neue Interaktionsparadigmen zu ebnen

Collaborative virtual reality platform for visualizing space data and mission planning

This paper presents the system architecture of a collaborative virtual environment in which distributed multidisciplinary teams involved in space exploration activities come together and explore areas of scientific interest of a planet for future missions. The aim is to reduce the current challenges of distributed scientific and engineering meetings that prevent the exploitation of their collaborative potential, as, at present, expertise, tools and datasets are fragmented. This paper investigates the functional characteristics of a software framework that addresses these challenges following the design science research methodology in the context of the space industry and research. An implementation of the proposed architecture and a validation process with end users, based on the execution of different use cases, are described. These use cases cover relevant aspects of real science analysis and operation, including planetary data visualization, as the system aims at being used in future European missions. This validation suggests that the system has the potential to enhance the way space scientists will conduct space science research in the future

Multiresolution Techniques for Real–Time Visualization of Urban Environments and Terrains

In recent times we are witnessing a steep increase in the availability of data coming from real–life environments. Nowadays, virtually everyone connected to the Internet may have instant access to a tremendous amount of data coming from satellite elevation maps, airborne time-of-flight scanners and digital cameras, street–level photographs and even cadastral maps. As for other, more traditional types of media such as pictures and videos, users of digital exploration softwares expect commodity hardware to exhibit good performance for interactive purposes, regardless of the dataset size. In this thesis we propose novel solutions to the problem of rendering large terrain and urban models on commodity platforms, both for local and remote exploration. Our solutions build on the concept of multiresolution representation, where alternative representations of the same data with different accuracy are used to selectively distribute the computational power, and consequently the visual accuracy, where it is more needed on the base of the user’s point of view. In particular, we will introduce an efficient multiresolution data compression technique for planar and spherical surfaces applied to terrain datasets which is able to handle huge amount of information at a planetary scale. We will also describe a novel data structure for compact storage and rendering of urban entities such as buildings to allow real–time exploration of cityscapes from a remote online repository. Moreover, we will show how recent technologies can be exploited to transparently integrate virtual exploration and general computer graphics techniques with web applications

Efficient Light and Sound Propagation in Refractive Media with Analytic Ray Curve Tracer

Refractive media is ubiquitous in the natural world, and light and sound propagation in refractive media leads to characteristic visual and acoustic phenomena. Those phenomena are critical for engineering applications to simulate with high accuracy requirements, and they can add to the perceived realism and sense of immersion for training and entertainment applications. Existing methods can be roughly divided into two categories with regard to their handling of propagation in refractive media; first category of methods makes simplifying assumption about the media or entirely excludes the consideration of refraction in order to achieve efficient propagation, while the second category of methods accommodates refraction but remains computationally expensive. In this dissertation, we present algorithms that achieve efficient and scalable propagation simulation of light and sound in refractive media, handling fully general media and scene configurations. Our approaches are based on ray tracing, which traditionally assumes homogeneous media and rectilinear rays. We replace the rectilinear rays with analytic ray curves as tracing primitives, which represent closed-form trajectory solutions based on assumptions of a locally constant media gradient. For general media profiles, the media can be spatially decomposed into explicit or implicit cells, within which the media gradient can be assumed constant, leading to an analytic ray path within that cell. Ray traversal of the media can therefore proceed in segments of ray curves. The first source of speedup comes from the fact that for smooth media, a locally constant media gradient assumption tends to stay valid for a larger area than the assumption of a locally constant media property. The second source of speedup is the constant-cost intersection computation of the analytic ray curves with planar surfaces. The third source of speedup comes from making the size of each cell and therefore each ray curve segment adaptive to the magnitude of media gradient. Interactions with boundary surfaces in the scene can be efficiently handled within this framework in two alternative approaches. For static scenes, boundary surfaces can be embedded into the explicit mesh of tetrahedral cells, and the mesh can be traversed and the embedded surfaces intersected with by the analytic ray curve in a unified manner. For dynamic scenes, implicit cells are used for media traversal, and boundary surface intersections can be handled separately by constructing hierarchical acceleration structures adapted from rectilinear ray tracer. The efficient handling of boundary surfaces is the fourth source of speedup of our propagation path computation. We demonstrate over two orders-of-magnitude performance improvement of our analytic ray tracing algorithms over prior methods for refractive light and sound propagation. We additionally present a complete sound-propagation simulation solution that matches the path computation efficiency achieved by the ray curve tracer. We develop efficient pressure computation algorithm based on analytic evaluations and combine our algorithm with the Gaussian beam for fast acoustic field computation. We validate the accuracy of the simulation results on published benchmarks, and we show the application of our algorithms on complex and general three-dimensional outdoor scenes. Our algorithms enable simulation scenarios that are simply not feasible with existing methods, and they have the potential of being extended and complementing other propagation methods for capability beyond handling refractive media.Doctor of Philosoph