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Publication Analysis of Left Ventricular Wall Motion Based on Volumetric Deformable Models and MRI-SPAMM(1996) Park, Jinah; Metaxas, Dimitris; Axel, LeonWe present a new approach for the analysis of the left ventricular shape and motion that is based on the development of a new class of volumetric deformable models. We estimate the deformation and complex motion of the left ventricle (LV) in terms of a few parameters that are functions and whose values vary locally across the LV. These parameters capture the radial and longitudinal contraction, the axial twisting, and the long-axis deformation. Using Lagrangian dynamics and the finite element theory, we convert these volumetric primitives into dynamic models that deform due to forces exerted by the datapoints. We present experiments where we used magnetic tagging (MIR-SPAMM) to acquire datapoints from the LV during systole. By applying our method to MRI_SPAMM datapoints, we were able to characterize both locally and globally the 3D shape and motion of the LV in a clinically useful way. In addition, based on the model parameters we were able to extract quantitative differences between normal and abnormal hearts and visualize them in a way that is useful to physicians.Publication Rule-Structured Facial Animation System(1993-08-28) Pelachaud, Catherine; Viaud, Marie-Luce; Yahia, HusseinOur overall goal is to produce as automatic as possible facial expressions with wrinkles from spoken input. We focus on two aspects of this problem: integration of the expressive wrinkles and generation of synchronized speech-animation. Our facial model integrates facial muscles deformations and bulges. We have produced a high level programming language to automatically drive 3D animation of facial expressions from speech. Our system embodies rule-governed translation from speech and utterance meaning to facial expressions. We are concerned primarily with expressions conveying information correlated with the intonation of the voice, some of which are also correlated with affect or emotion. We apply our automatic animation model to a new facial animation system which integrates effects of the facial motion as expressive wrinkles and muscles dependencies. We obtain then with this subtle criteria of modeling and motion an animation much more expressive and natural.Publication The Topic is Open(1993) Levison, LibbyWe can open a door, open an umbrella, or open a jar; we open the safe (open the door of the safe), open the cookies (open the box and plastic pouch) and open a valve (turn the knob and open the pipe). I take open to mean CAUSE X TO BE OPEN and to describe the process of opening. given the diversity that occurs, is it possible to characterize the objects of a verb like open? In this paper I argue that there are similarities among the possible physical objects of the verb open, based on the objects; underlying geometric structure. This regularity, derived from an analysis of tokens extracted from the Brown corpus, is used in the remainder of the paper to analyze similarities amongst abstract use of open: (open a meeting, open a gulf). The proposed analysis also explain limits in usage: #open the chair; #open the question.Publication Behavioral Control for Real-Time Simulated Human Agents(1995-04-02) Granieri, John P; Becket, Welton; Reich, Barry D; Crabtree, Jonathan; Badler, Norman IA system for controlling the behaviors of an interactive human-like agent and executing them in real-time, is presented. It relies on an underlying model of continuous behavior, as well as a discrete scheduling mechanism for changing behavior over time. A multiprocessing framework executes the behaviors and renders the motion of the agents in real-time. Finally, we discuss the current state of our implementation and some areas of future work.Publication 3D Human Body Model Acquisition from Multiple Views(1995-06-20) Kakadiaris, Ioannis A; Metaxas, DimitrisWe present a novel motion-based approach for the part determination and shape estimation of a human’s body parts. The novelty of the technique is that neither a prior model of the human body is employed nor prior body part segmentation is assumed. We present a Human Body Part Identification Strategy (HBPIS) that recovers all the body parts of a moving human based on the spatiotemporal analysis of its deforming silhouette. We formalize the process of simultaneous part determination, and 2D shape estimation by employing the Supervisory Control Theory of Discrete Event Systems. In addition, in order to acquire the 3D shape of the body parts, we present a new algorithm which selectively integrates the (segmented by the HBPIS) apparent contours, from three mutually orthogonal views. The effectiveness of the approach is demonstrated through a series of experiments, where a subject performs a set of movements according to a protocol that reveals the structure of the human body.Publication Planning for Reactive Behaviors in Hide and Seek(1995-05-01) Moore, Michael B; Geib, Christopher W; Reich, Barry DWe describe the ZAROFF system, a plan-based controller for the players in a game of hide and seek. The system features visually realistic human figure animation including realistic human locomotion. We discuss the planner's interaction with a changing environment to which it has only limited perceptual access. A hierarchical planner translates the game's goals of finding hiding players into locomotion goals, assisted by a special-purpose search planner. We describe a system of parallel finite state machines for controlling the player's locomotion. Neither path-planning nor explicit instructions are used to drive locomotion; agent control and apparent complexity are the result of the interaction of a few relatively simple behaviors with a complex (and changing) environment.Publication Animation through Reactions, Transition Nets and Plans(1995-10-01) Webber, Bonnie L; Badler, Norman IWe describe a framework for creating animated simulations of virtual human agents. The framework allows us to capture flexible patterns of activity, as well as reactivity to a changing environment. Both lead to variation in how an animated simulation will be realized. In addition, because different parts of an activity make different demands on an agent's resources and decision-making, our framework allows special-purpose reasoners and planners to be associated with only those phases of an activity where they are needed.Publication Planning and Parallel Transition Networks: Animation's New Frontiers(1995) Badler, Norman I; Webber, Bonnie L; Becket, Welton; Geib, Christopher W; Moore, Michael B; Pelachaud, Catherine; Reich, Barry D; Stone, MatthewAnimating realistic human agents involves more than just creating movements that look "real". A principal characteristic of humans is their ability to plan and make decisions based on intentions and the local environmental context. "Animated agents" must therefore react to and deliberate about their environment and other agents. Our agent animation uses various low-level behaviors, sense-control-action loops, high-level planning, and parallel task networks. Several systems we developed will illustrate how these components contribute to the realism and efficacy of human agent animation.Publication Autonomous Animation and Control of Four-Legged Animals(1995) Kokkevis, Evangelos; Metaxas, Dimitris; Badler, Norman IThis paper develops a framework for the realistic autonomous animation and motion control of four-legged animals. Our system uses a combination of kinematics, dynamics and control theory. The input to our system, the velocity and heading of the animal, originates either from a simulated visual sensory system or a user. Based on this input we model walking, trotting, and simple behaviors such as target pursuit. we use a combination of kinematics, dynamics and control theory. A feedback controller, using the desired velocity and animal heading, computes the aggregate force and torque vector that should be applied to the body to achieve the given motion. This force and torque is distributed to the legs in contact with the ground through a linear programming algorithm. We then use forward dynamics to compute the actual body displacement. A kinematic gait controller is in charge of the stepping pattern. It arranges the stance and transfer phases of each leg depending on the current locomotion velocity, the turning rate and the ground conditions. Although we chose to focus on four-legged animals, the approach is generalizable to other multi-legged creatures or biped locomotion. Our motion system can currently simulate variable speed walking and trotting on flat or uneven terrain. Given its flexibility, the system can be used as a basis for more complex animations involving high level behaviors and interactions with other animals.Publication A Temporal Image-Based Approach to Motion Reconstruction for Globally Illuminated Animated Environments(1996-06-17) Nimeroff, JeffryThis paper presents an approach to motion sampling and reconstruction for globally illuminated animated environments (under fixed viewing conditions) based on sparse spatio-temporal scene sampling, a resolution-independent temporal file format, and a Delaunay triangulation pixel reconstruction method. The argument is made that motion that is usually achieved by rendering complete images of a scene at a high frame rate (i.e. flipbook style frame-based animation) can be adequately reconstructed using many less samples (often on the order of that required to generate a single, complete, high quality frame) from the sparse image data stored in bounded slices of our temporal file. The scene is rendered using a ray tracing algorithm modified to randomly sample over space - the image plane (x, y), and time (t), yielding (x, y, t) samples that are stored in our spatio-temporal images. Reconstruction of object motion, reconstructing a picture of the scene at a desired time, is performed by projecting the (x, y, t) samples onto the desired temporal plane with the appropriate weighting, constructing the 2D Delaunay triangulation of the sample points, and Gouraud (or Phong) shading the resulting triangles. Both first and higher order visual effects, illumination and visibility, are handled. Silhouette edges and other discontinuities are more difficult to track but can be addressed with a combination of triangle filtering and image postprocessing.