Dynamic textures are sequences of images of moving scenes that exhibit certain stationarity properties in time; these include sea-waves, smoke, foliage, whirlwind etc. We present a novel characterization of dynamic textures that poses the problems of modeling, learning, recognizing and synthesizing dynamic textures on a firm analytical footing. We borrow tools from system identification to capture the "essence" of dynamic textures; we do so by learning (i.e. identifying) models that are optimal in the sense of maximum likelihood or minimum prediction error variance. For the special case of second-order stationary processes, we identify the model sub-optimally in closed-form. Once learned, a model has predictive power and can be used for extrapolating synthetic sequences to infinite length with negligible computational cost. We present experimental evidence that, within our framework, even low-dimensional models can capture very complex visual phenomena.

This paper introduces a combined discrete/continuous model of plant development that integrates L-system-style productions and differential equations. The model is suitable for animating simulated developmental processes in a manner resembling time-lapse photography. The proposed technique is illustrated using several developmental models, including the flowering plants Campanula rapunculoides, Lychnis coronaria, and Hieracium umbellatum. CR categories: F.4.2 [Mathematical Logic and Formal Languages ]: Grammars and Other Rewriting Systems: Parallel rewriting systems, I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism: Animation, I.6.3 [Simulation and Modeling ]: Applications, J.3 [Life and Medical Sciences]: Biology Keywords: animation through simulation, realistic image synthesis, modeling of plants, combined discrete/continuous simulation, L-system, piecewise-continuous differential equation. 1 INTRODUCTION Time-lapse photography reveals the enormous visual appeal...

... design and development. It is tremendously difficult to observe, communicate with and test underwater robots, because they operate in a remote and hazardous environment where physical dynamics and sensing modalities are counterintuitive. An underwater virtual world can comprehensively model all salient functional characteristics of the real world in real time. This virtual world is designed from the perspective of the robot, enabling realistic AUV evaluation and testing in the laboratory. Three-dimensional real-time computer graphics are our window into that virtual world. Visualization of robot interactions within a virtual world permits sophisticated analyses of robot performance that are otherwise unavailable. Sonar visualization permits researchers to accurately "look over the robot’s shoulder " or even "see through the robot’s eyes " to intuitively understand sensor-environment interactions. Extending the theoretical derivation of a set of six-degree-of-freedom hydrodynamics equations has provided a fully general physics-based model capable of producing highly non-linear yet experimentallyverifiable response in real time. Distribution of underwater virtual world components enables scalability and real-time response. The IEEE Distributed Interactive Simulation (DIS) protocol is used for compatible live interaction with other virtual worlds. Network connections allow remote access, demonstrated via Multicast Backbone (MBone) audio and video collaboration with researchers at remote locations. Integrating the World-Wide Web allows rapid access to resources distributed across the Internet. This dissertation presents the frontier of 3D real-time graphics to support underwater robotics, scientific ocean exploration, sonar visualization and worldwide collaboration.

Computer simulation is a fundamental discipline for studying complex systems. Like any other discipline, simulation must grow and be fine-tuned so that it maintains its position as the base methodology for doing computational science and constructing digital worlds. We discuss ten areas outside of simulation and demonstrate growth by identifying relationships between simulation and each of the areas. We outline each field by describing it briefly and then specifying outstanding issues which remain to be resolved. We have found that we are better able to characterize basic simulation methodology by integrating and extending simulation within the context of other fields. INTRODUCTION The field of computer simulation is approximately forty years old, and is still vibrant and growing. As technology develops faster hardware, old forms of simulation are made faster, and new varieties of simulation emerge through an extension process. Extending the core simulation knowledge base involves tak...

This paper describes technology and tools for intelligent human-computer interaction (IHCI) where human cognitive, perceptual, motor, and affective factors are modeled and used to adapt the H--C interface. IHCI emphasizes that human behavior encompasses both apparent human behavior and the hidden mental state behind behavioral performance. IHCI expands on the interpretation of human activities, known as W4 (what, where, when, who). While W4 only addresses the apparent perceptual aspect of human behavior, the W5+ technology for IHCI described in this paper addresses also the why and how questions, whose solution requires recognizing specific cognitive states. IHCI integrates parsing and interpretation of nonverbal information with a computational cognitive model of the user, which, in turn, feeds into processes that adapt the interface to enhance operator performance and provide for rational decision-making. The technology proposed is based on a general four-stage interactive framework, which moves from parsing the raw sensory-motor input, to interpreting the user's motions and emotions, to building an understanding of the user's current cognitive state. It then diagnoses various problems in the situation and adapts the interface appropriately. The interactive component of the system improves processing at each stage. Examples of perceptual, behavioral, and cognitive tools are described throughout the paper. Adaptive and intelligent HCI are important for novel applications of computing, including ubiquitous and human-centered computing

Dealing with synthetic actors who move and behave realistically in virtual environments is a task which involves different disciplines like Mechanics, Physics, Robotics, Artificial Intelligence, Artificial Life, Biology, Cognitive Sciences and so on. In this paper we use the nature of the information required for controlling actors' motion and behaviour to propose a new classi"cation of synthetic actors. A description of the different motion and behaviour techniques is presented. A set of Internet addresses of the most relevant research groups, commercial companies and other related sites in this

The World Wide Web as a repository of information has had a great influence on our lives. This influence is increasing as the web introduces applications in addition to information. These applications have several advantages, such as world wide accessibility, distance group learning and collaboration. Furthermore, the web encourages training applications since it offers multi-media that can support all stages of training. On the other hand, the virtual reality technology has been utilised to provide new systematic training methods for surgical procedures. These solutions are usually expensive in terms of cost and computation. In this thesis we propose a novel solution to fulfill the training needs of radiologists performing one type of minimally invasive surgery known as interventional radiology. Our training method combines the capabilities of virtual reality to provide realistic simulation environment together with the web environment to provide platform independent, scalable and acc...

A major unsolved problem in computer graphics is that of making high-quality models. Traditionally, models have consisted of interactively or algorithmically described collections of graphics primitives such as polygons. The process of constructing these models is painstaking and often misses features and behavior that we wish to model. Models extracted from volume data collected from real, physical objects have the potential to show features and behavior that are difficult to capture using these traditional modeling methods. We use vector-valued magnetic resonance volume data in this thesis. The process of extracting models from such data involves four main steps: collecting the sampled volume data; preprocessing it to reduce artifacts from the collection process; classifying materials within the data; and creating either a rigid geometric model that is static, or a flexible, dynamic model that can be simulated. In this thesis we focus on the the first three steps. We present guidelin...

This thesis develops an engineering practice and design methodology to enable us to use CMOS analog VLSI chips to perform more accurate and precise computation. These techniques form the basis of an approach that permits us to build computer graphics and neural network applications using analog VLSI. The nature of the design methodology focuses on defining goals for circuit behavior to be met as part of the design process. To increase the accuracy of analog computation, we develop techniques for creating compensated circuit building blocks, where compensation implies the cancellation of device variations, offsets, and nonlinearities. These compensated building blocks can be used as components in larger and more complex circuits, which can then also be compensated. To this end, we develop techniques for automatically determining appropriate parameters for circuits, using constrained optimization. We also fabricate circuits that implement multi-dimensional gradient estimation for a grad...

This paper describes a simulator which uses a unique hybrid particle system and dynamic constraint based model to compute the behaviour of interacting multibody systems in a virtual environment. Simulations can be influenced by the user at run-time, so there are important interaction issues addressed. The need for such systems in virtual reality applications ranging from tissue modelling in surgical training software to use in entertainment, is apparent. Purely, a visual effect does not suffice in this context, as the behaviour of objects in the scene must be plausible enough to convince the user. Our approach provides a unified system for simulating a wide spectrum of deformable and/or rigid material behaviours in virtual environments. An example of a virtual chain, which the user can interact with, is provided. Keywords: constraint based, physically based, interaction forces, rigid bodies, multi bodies, particle systems, virtual reality. 1 Introduction To simulate the behaviour of ...