Physically Based Animation of sea Anemones in Real-Time

This paper presents a technique for modeling and animating fiberlike objects such as sea anemones tentacles in real-time. Each fiber is described by a generalized cylinder defined around an articulated skeleton. The dynamics of each individual fiber is controlled by a physically based simulation that updates the position of the skeleton’s frames over time. We take into account the forces generated by the surrounding fluid as well as a stiffness function describing the bending behavior of the fiber. High level control of the animation is achieved through the use of four types of singularities to describe the three-dimensional continuous velocity field representing the fluid. We thus animate hundreds of fibers by key-framing only a small number of singularities. We apply this algorithm on a seascape composed of many sea anemones. We also show that our algorithm is more general and can be applied to other types of objects composed of fibers such as seagrasse

An Interactive Forest

International audienceWe present a prototype of a forest in which a video game player can move and interact physically with the trees. The trees are procedurally built on-the-fly at each redraw. Two animation approaches are combined: a procedural method which handles most of the trees efficiently, and a physically-based method which allows user interaction with the trees. The physically-based method is dynamically applied only where needed. Physical data is computed only where the physical method is applied, and deleted afterwards. Smooth transitions between animation methods are performed. Levels of detail are used for rendering and for procedural animation. Our method allows the display and the animation, including user action, of a 256-tree forest at interactive rates

Hierarchical retargetting of 2D motion fields to the animation of 3D plant models

International audienceThe complexity of animating trees, shrubs and foliage is an impediment to the efficient and realistic depiction of natural environments. This paper presents an algorithm to extract, from a single video sequence, motion fields of real shrubs under the influence of wind, and to transfer this motion to the animation of complex, synthetic 3D plant models. The extracted motion is retargeted without requiring physical simulation. First, feature tracking is applied to the video footage, allowing the 2D position and velocity of automatically identified features to be clustered. A key contribution of the method is that the hierarchy obtained through statistical clustering can be used to synthesize a 2D hierarchical geometric structure of branches that terminates according to the cut-off threshold of a classification algorithm. This step extracts both the shape and the motion of a hierarchy of features groups that are identified as geometrical branches. The 2D hierarchy is then extended to three dimensions using the estimated spatial distribution of the features within each group. Another key contribution is that this 3D hierarchical structure can be efficiently used as a motion controller to animate any complex 3D model of similar but non-identical plants using a standard skinning algorithm. Thus, a single video source of a moving shrub becomes an input device for a large class of virtual shrubs. We illustrate the results on two examples of shrubs and one outdoor tree. Extensions to other outdoor plants are discussed

View-dependent dynamics of articulated bodies

Special Issue: CASA'2008 Special IssueInternational audienceWe propose a method for view-dependent simplification of articulated-body dynamics, which enables an automatic trade-off between visual precision and computational efficiency. We begin by discussing the problem of simplifying the simulation based on visual criteria, and show that it raises a number of challenging questions. We then focus on articulated-body dynamics simulation, and propose a semi-predictive approach which relies on a combination of exact, a priori error metrics computations, and visibility estimations. We suggest several variants of semi-predictive metrics based on hierarchical data structures and the use of graphics hardware, and discuss their relative merits in terms of computational efficiency and precision. Finally, we present several benchmarks and demonstrate how our view-dependent articulated-body dynamics method allows an animator (or a physics engine) to finely tune the visual quality and obtain potentially significant speedups during interactive or off-line simulations

Resolution independent curved seams in clothing animation using a regular particle grid

We present a method for representing seams in clothing animation, and its application in simulation level of detail. Specifically we consider cloth represented as a regular grid of particles connected by spring-dampers, and a seam specified by a closed set of parametric trim curves in the cloth domain. Conventional cloth animation requires the tessellation of seams so that they are handled uniformly by the dynamics process. Our goal is a seam definition which does not constrain the attached clothing panels to be of the same resolution, or even constant resolution, while not being a hindrance to the dynamics process. We also apply our seams to cloth defined on a regular grid, as opposed to the irregular meshes commonly used with seams. The determination of particles interior to the cloth panel can be done using wellknown graphics operations such as scan-conversion. Due to the particle-based nature of the simulation, the dynamics approach combines easily with existing implicit and explicit methods. Finally, because the seams are resolution independent, the particle density per clothing panel can be adjusted as desired. This gives rise to a simple application of the given seams approach illustrating how it may be used for simulation level of detail

Real-time fur modeling with simulation of physical effects

Ankara : The Department of Computer Engineering and the Graduate School of Engineering and Science of Bilkent University, 2012.Thesis (Master's) -- Bilkent University, 2012.Includes bibliographical references leaves 51-54.Fur is one of the important visual aspects of animals and it is quite challenging to model it in computer graphics. This is due to rendering and animating high amounts of geometry taking excessive time in our personal computers. Thus in computer games most of the animals are without fur or covered with a single layer of texture. But these current methods do not provide the reality and even if the rendering in the game is realistic the fur is omitted. There have been several models to render a fur, but the methods that incorporate rendering are not in real-time, on the other hand most of the real-time methods omit many of the natural aspects , such as; texture lighting, shadow and animation. Thus the outcome is not sufficient for realistic gaming experience. In this thesis we propose a real-time fur represantation that can be used on 3D objects. Moreover, we demonstrate how to; render, animate and burn this real-time fur.Arıyürek, SinanM.S

Modélisation et animation de la mer en temps réel

National audienceDepuis toujours, dans le domaine de la synthèse d'images, la mer fait l'objet de nombreux travaux. Mais il est impossible de représenter tous les aspects du phénomène de la même façon. Depuis quelques années, sa simulation, dans le domaine des effets spéciaux, atteint une qualité visuelle photoréaliste. Mais la mer, malgré la place qu'elle occupe sur nore planète, est pratiquement absente du principal domaine du temps réel, les jeux vidéos. Le but de se travail est developper une méthode en temps réel d'animation et de rendu de la mer , scène relativement complexe par nature qui se prète bien 'a la recherche de techniques d'optimisations des méthodes d'animation en temps réel

Physically based animation and fast rendering of large-scale prairie

Master'sMASTER OF SCIENC

Real-time Realistic Rendering Of Nature Scenes With Dynamic Lighting

Rendering of natural scenes has interested the scientific community for a long time due to its numerous applications. The targeted goal is to create images that are similar to what a viewer can see in real life with his/her eyes. The main obstacle is complexity: nature scenes from real life contain a huge number of small details that are hard to model, take a lot of time to render and require a huge amount of memory unavailable in current computers. This complexity mainly comes from geometry and lighting. The goal of our research is to overcome this complexity and to achieve real-time rendering of nature scenes while providing visually convincing dynamic global illumination. Our work focuses on grass and trees as they are commonly visible in everyday life. We handle geometry and lighting complexities for grass to render millions of grass blades interactively with dynamic lighting. As for lighting complexity, we address real-time rendering of trees by proposing a lighting model that handles indirect lighting. Our work makes extensive use of the current generation of Graphics Processing Units (GPUs) to meet the real-time requirement and to leave the CPU free to carry out other tasks