Research in constraint-based layout, visualization, CAD, and related topics : a bibliographical survey

The present work compiles numerous papers in the area of computer-aided design, graphics, layout configuration, and user interfaces in general. There is nearly no conference on graphics, multimedia, and user interfaces that does not include a section on constraint-based graphics; on the other hand most conferences on constraint processing favour applications in graphics. This work of bibliographical pointers may serve as a basis for a detailed and comprehensive survey of this important and challenging field in the intersection of constraint processing and graphics. In order to reach this ambitious aim, and also to keep this study up-to-date, the authors appreciate any comment and update information

Analysis and synthesis of bipedal humanoid movement : a physical simulation approach

textAdvances in graphics and robotics have increased the importance of tools for synthesizing humanoid movements to control animated characters and physical robots. There is also an increasing need for analyzing human movements for clinical diagnosis and rehabilitation. Existing tools can be expensive, inefficient, or difficult to use. Using simulated physics and motion capture to develop an interactive virtual reality environment, we capture natural human movements in response to controlled stimuli. This research then applies insights into the mathematics underlying physics simulation to adapt the physics solver to support many important tasks involved in analyzing and synthesizing humanoid movement. These tasks include fitting an articulated physical model to motion capture data, modifying the model pose to achieve a desired configuration (inverse kinematics), inferring internal torques consistent with changing pose data (inverse dynamics), and transferring a movement from one model to another model (retargeting). The result is a powerful and intuitive process for analyzing and synthesizing movement in a single unified framework.Computer Science

3D User Interfaces for General-Purpose 3D Animation

Draft submission, Appeared as "3D User Interfaces for General-Purpose 3D Animation"Modern 3D animation systems let a growing number of people generate increasingly sophisticated animated movies, frequently for tutorials or multimedia documents. However, although these tasks are inherently three dimensional, these systems' user interfaces are still predominantly two dimensional. This makes it difficult to interactively input complex animated 3D movements. We have developed Virtual Studio, an inexpensive and easy-to-use 3D animation environment in which animators can perform all interaction directly in three dimensions. Animators can use 3D devices to specify complex 3D motions. Virtual tools are visible mediators that provide interaction metaphors to control application objects. An underlying constraint solver lets animators tightly couple application and interface objects. Users define animation by recording the effect of their manipulations on models. Virtual Studio applies data-reduction techniques to generate editable representations of each animated element that is manipulated.71-78Pubblicat

Real-time deformation and fracture in a game environment

This paper describes a simulation system that has been developed to model the deformation and fracture of solid objects in a real-time gaming context. Based around a corotational tetrahedral finite element method, this system has been constructed from components published in the graphics and computational physics literatures. The goal of this paper is to describe how these components can be combined to produce an engine that is robust to unpredictable user interactions, fast enough to model reasonable scenarios at real-time speeds, suitable for use in the design of a game level, and with appropriate controls allowing content creators to match artistic direction. Details concerning parallel implementation, solver design, rendering method, and other aspects of the simulation are elucidated with the intent of providing a guide to others wishing to implement similar systems. Examples from in-game scenes captured on the Xbox 360, PS3, and PC platforms are included. © 2009 ACM

Generating Human Motion by Symbolic Reasoning

This paper describes work on applying AI planning methods to generate human body motion for the purpose of animation. It is based on the fact that although we do not know how the body actually controls massively redundant degrees of freedom of its joints and moves in given situations, the appropriateness of specific behavior for particular conditions can be axiomatized at a gross level using commonsensical observations. Given the motion axioms (rules), the task of the planner is to find a discrete sequence of intermediate postures of the body via goal reduction reasoning based on the rules along with a procedure to discover specific collision-avoidance constraints, such that any two consecutive postures are related via primitive motions of the feet, the pelvis, the torso, the head, the hands, or other body parts. Our planner also takes account of the fact that body motions are continuous by taking advantage of execution-time feedback. Planning decisions are made in the task space where our elementary spatial intuition is preserved as far as possible, only dropping down to a joint space formulation typical in robot motion planning when absolutely necessary. We claim that our work is the first serious attempt to use an AI planning paradigm for animation of human body motion

Data-Augmented Contact Model for Rigid Body Simulation

Accurately modeling contact behaviors for real-world, near-rigid materials remains a grand challenge for existing rigid-body physics simulators. This paper introduces a data-augmented contact model that incorporates analytical solutions with observed data to predict the 3D contact impulse which could result in rigid bodies bouncing, sliding or spinning in all directions. Our method enhances the expressiveness of the standard Coulomb contact model by learning the contact behaviors from the observed data, while preserving the fundamental contact constraints whenever possible. For example, a classifier is trained to approximate the transitions between static and dynamic frictions, while non-penetration constraint during collision is enforced analytically. Our method computes the aggregated effect of contact for the entire rigid body, instead of predicting the contact force for each contact point individually, removing the exponential decline in accuracy as the number of contact points increases.Comment: 7 pages, 7 figures. Submitted to ICRA 2019. Added video attachment with full 3D experiments: https://youtu.be/AKSD8TabDV

Computational design of skinned Quad-Robots

We present a computational design system that assists users to model, optimize, and fabricate quad-robots with soft skins. Our system addresses the challenging task of predicting their physical behavior by fully integrating the multibody dynamics of the mechanical skeleton and the elastic behavior of the soft skin. The developed motion control strategy uses an alternating optimization scheme to avoid expensive full space time-optimization, interleaving space-time optimization for the skeleton, and frame-by-frame optimization for the full dynamics. The output are motor torques to drive the robot to achieve a user prescribed motion trajectory. We also provide a collection of convenient engineering tools and empirical manufacturing guidance to support the fabrication of the designed quad-robot. We validate the feasibility of designs generated with our system through physics simulations and with a physically-fabricated prototype