Key Probe: a technique for animation keyframe extraction

We present a novel constraint-based keyframe extraction technique, Key Probe. Based on animator-specified constraints, the method converts a skeleton-based motion or animated mesh to a keyframe-based representation. In contrast to previous curve simplification or clustering methods, we cast the keyframe extraction problem as a constrained matrix factorization problem and solve the problem based on the least-squares optimization technique. The extracted keyframes have two uses: they could be used for browsing or they may be blended to reconstruct all other frames of an animation. Our approach is general and suitable for both rigid-body and soft-body animations. Experiments on various types of animation examples show that the proposed method produces remarkable results in terms of quality and compression ratio. Empirical tests also show that our algorithm consistently offers better efficiency than those by principal component analysis (PCA) and independent component analysis (ICA).     

An automated technique for real-time production of lifelike animations of American Sign Language

Generating sentences from a library of signs implemented through a sparse set of key frames derived from the segmental structure of a phonetic model of ASL has the advantage of flexibility and efficiency, but lacks the lifelike detail of motion capture. These difficulties are compounded when faced with real-time generation and display. This paper describes a technique for automatically adding realism without the expense of manually animating the requisite detail. The new technique layers transparently over and modifies the primary motions dictated by the segmental model and does so with very little computational cost, enabling real-time production and display. The paper also discusses avatar optimizations that can lower the rendering overhead in real-time displays.     

Optimal and interactive keyframe selection for motion capture

Computational Visual Media - Motion capture is increasingly used in games and movies, but often requires editing before it can be used, for many reasons. The motion may need to be adjusted to...     

Accurate keyframe selection and keypoint tracking for robust visual odometry

This paper presents a novel stereo visual odometry (VO) framework based on structure from motion, where a robust keypoint tracking and matching is combined with an effective keyframe selection strategy. In order to track and find correct feature correspondences a robust loop chain matching scheme on two consecutive stereo pairs is introduced. Keyframe selection is based on the proportion of features with high temporal disparity. This criterion relies on the observation that the error in the pose estimation propagates from the uncertainty of 3D points—higher for distant points, that have low 2D motion. Comparative results based on three VO datasets show that the proposed solution is remarkably effective and robust even for very long path lengths.     

Procedural models for cartoon cracks and fractures animations

We present an approach for animating cracks and fractures in cartoon style. In our method we take a 2D hand-drawn object as input and then construct a 2.5D model of the object in order to approximate the object volume. Next, we generate the Voronoi textures on the 2.5D object model for visual abstraction of cartoon cracks. Further, cracking gaps on the Voronoi textures are widened progressively until Voronoi cells split apart and finally fall onto ground according to simplified physical rules. With minimum user intervention, our model is able to generate cartoon cracks and fractures animations procedurally, as demonstrated by examples given in the paper.     

A performance-based parallel loop scheduling on grid environments

The effectiveness of loop self-scheduling schemes has been shown on traditional multiprocessors in the past and computing clusters in the recent years. However, parallel loop scheduling has not been widely applied to computing grids, which are characterized by heterogeneous resources and dynamic environments. In this paper, a performance-based approach, taking the two characteristics above into consideration, is proposed to schedule parallel loop iterations on grid environments. Furthermore, we use a parameter, SWR, to estimate the proportion of the workload which can be scheduled statically, thus alleviating the effect of irregular workloads. Experimental results on a grid testbed show that the proposed approach can reduce the completion time for applications with regular or irregular workloads. Consequently, we claim that parallel loop scheduling can benefit applications on grid environments.     

Designing large‐scale interactive traffic animations for urban modeling

Designing and optimizing traffic behavior and animation is a challenging problem of interest to virtual environment content generation and to urban planning and design. While some traffic simulation methods have appeared in computer graphics, most related systems focus on the design of buildings, roads, or cities but without explicitly considering urban traffic. To our knowledge, our work provides the first interactive approach which enables a designer to specify a desired vehicular traffic behavior (e.g., road occupancy, travel time, emissions, etc.) and the system will automatically compute what realistic 3D urban model (e.g., an interconnected network of roads, parcels, and buildings) yields the specified behavior. Our system both altered and improved traffic behavior in novel procedurally‐generated cities and in road networks of existing cities. Our urban models contain up to 360 km of roads, 300,000 vehicles, and typically cover four hours of simulated peak traffic time. The typical editing session time to “paint” a new traffic pattern and to compute the new/changed urban model is two to five minutes.     

OFDM系统定时同步技术研究

在分析以往算法的基础上,提出了一种改进的定时同步算法。它克服了以往算法的缺陷,所采用的自相关算法对频率偏差具有较强的鲁棒性。仿真分析表明该算法在多径信道中其性能仍然较好。提出的算法比较简单,而且开销较低。     

3D Hair sketching for real-time dynamic & key frame animations

Physically based simulation of human hair is a well studied and well known problem. But the “pure” physically based representation of hair (and other animation elements) is not the only concern of the animators, who want to “control” the creation and animation phases of the content. This paper describes a sketch-based tool, with which a user can both create hair models with different styling parameters and produce animations of these created hair models using physically and key frame-based techniques. The model creation and animation production tasks are all performed with direct manipulation techniques in real-time.     

School-based optimization for performance-based optimum seismic design of steel frames

The performance-based optimum seismic design of steel frames is one of the most complicated and computationally demanding structural optimization problems. Metaheuristic optimization methods have been successfully used for solving engineering design problems over the last three decades. A very recently developed metaheuristic method called school-based optimization (SBO) will be utilized in the performance-based optimum seismic design of steel frames for the first time in this study. The SBO actually is an improved/enhanced version of teaching–learning-based optimization (TLBO), which mimics the teaching and learning process in a class where learners interact with the teacher and between themselves. Ad hoc strategies are adopted in order to minimize the computational cost of SBO results. The objective of the optimization problem is to minimize the weight of steel frames under interstory drift and strength constraints. Three steel frames previously designed by different metaheuristic methods including particle swarm optimization, improved quantum particle swarm optimization, firefly and modified firefly algorithms, teaching–learning-based optimization, and JAYA algorithm are used as benchmark optimization examples to verify the efficiency and robustness of the present SBO algorithm. Optimization results are compared with those of other state-of-the-art metaheuristic algorithms in terms of minimum structural weight, convergence speed, and several statistical parameters. Remarkably, in all test problems, SBO finds lighter designs with less computational effort than the TLBO and other methods available in metaheuristic optimization literature.

     

A stochastic control model for optimal timing of climate policies

A stochastic control model is proposed as a paradigm for the design of optimal timing of greenhouse gas (GHG) emission abatement. The resolution of uncertainty concerning climate sensitivity and the technological breakthrough providing access to a carbon-free production economy are modeled as controlled stochastic jump processes. The optimal policy is characterized using the dynamic programming solution to a piecewise deterministic optimal control problem. A numerical illustration is developed with a set of parameters calibrated on recently proposed models for integrated assessment of climate policies. The results are interpreted and the insights they provide on the timing issue of climate policy are discussed.     

A timing model for vision-based control of industrial robot manipulators

Visual sensing for robotics has been around for decades, but our understanding of a timing model remains crude. By timing model, we refer to the delays (processing lag and motion lag) between "reality" (when a part is sensed), through data processing (the processing of image data to determine part position and orientation), through control (the computation and initiation of robot motion), through "arrival" (when the robot reaches the commanded goal). In this study, we introduce a timing model where sensing and control operate asynchronously. We apply this model to a robotic workcell consisting of a Sta/spl uml/ubli RX-130 industrial robot manipulator, a network of six cameras for sensing, and an off-the-shelf Adept MV-19 controller. We present experiments to demonstrate how the model can be applied.     

Optimal decision for the target value of performance-based structural system reliability

The optimal decision model of the target value of performance-based structural system reliability is established according to the cost-effectiveness criterion in the present paper. Three types of optimal decision models are studied: the conceptive model, the parameter programming model and the constraint relaxation model. The conceptive model is inoperable because the objective function must be expressed as the function of the structural target reliability. The parameter programming and constraint relax models are proved to be equivalent with Kuhn–Tucker conditions when the performance-based structural system reliability constraints are all active. Finally the numerical examples of RC-frames for different earthquake-resistant performance are calculated. Received February 5, 2000     

Promoting healthy computer use: timing-informed computer health animations for prolonged sitting computer users

Accompanying the increase in computer and Internet use worldwide, physical inactivity has become prevalent in most developed and developing countries. Extended computer use may contribute to symptoms such as visual impairment and musculoskeletal disorders. To reduce the risk of physical inactivity and promote healthier computer use, this study tries to develop a timed broadcast of health-related animations for users sitting at computers for prolonged periods. In addition, we examine the effects that the program has on the computer-related health beliefs and behaviour of participants. Before-and-after survey questionnaires were used for data collection. The results show that the animation program indeed had a positive effect when reminding participants to take a break and stretch their bodies. The program influenced the beliefs and behaviours of participants with regard to their health. The development and examination were documented and discussed within the context of health agencies planning the next steps in an effort to promote, develop and evaluate healthy computer use.     

一种针对突发OFDM信号的定时同步新算法

在正交频分复用(OFDM)系统中,定时同步和频偏估计对系统性能起着关键作用。给出了基于IEEE802.11a的突发OFDM系统模型,利用突发OFDM本身所具有的前导字,提出了一种易于硬件实现的定时同步估计算法,仿真结果表明该算法能较好地适应突发OFDM系统在短时间内快速定时的要求。     

A built-in parametric timing measurement unit

On-chip timing-measurement units are needed because accessibility to internal nodes in SoCs is very limited, and performing time interval measurements using automatic test equipment is very difficult and expensive. We present a parametric timing measurement solution, which uses self-timed techniques and delivers high linearity and improved accuracy, at low risk of measurement error. Performing the time-to-digital conversion via built-in circuitry allows accurate measurement of short time intervals and setup/hold time. This circuitry coordinates well with low-cost ATE. To achieve this solution, researchers have used techniques such as delay matrices, phase-locked loops (PLLs), and dual-slope conversion.     

A technique for dual adaptive control

We present a new adaptive control scheme where the control is chosen both to regulate and to elicit information. This is done by minimizing the one-step-ahead expected squared output, subject to a constraint on the trace of the one-step-ahead information matrix. We also incorporate a covariance-adaptive feature in the algorithm. Simulation results are given to compare the performance of this method to that of the perturbation controller of Wieslander and Wittenmark.