Supporting cartoon animation techniques in direct manipulation graphical user interfaces

If judiciously applied, the techniques of cartoon animation can enhance the illusion of direct manipulation that many human computer interfaces strive to present. In particular, animation can convey a feeling of substance in the objects that a user manipulates, strengthening the sense that real work is being done. This paper describes algorithms and implementation issues to support cartoon style graphical object distortion effects for direct manipulation user interfaces. Our approach is based on suggesting a range of animation effects by distorting the view of the manipulated object. To explore the idea, we added a warping transformation capability to the InterViews user interface toolkit.     

3D Metamorphosis Between Different Types of Geometric Models

We present a powerful morphing technique based on level set methods, that can be combined with a variety of scan conversion/model processing techniques. Bringing these techniques together creates a general morphing approach that allows a user to morph a number of geometric model types in a single animation. We have developed techniques for converting several types of geometric models (polygonal meshes, CSG models and MRI scans) into distance volumes, the volumetric representation required by our level set morphing approach. The combination of these two capabilities allows a user to create a morphing sequence regardless of the model type of the source and target objects, freeing him/her to use whatever model type is appropriate for a particular animation.     

基于物理及数据驱动的流体动画研究

主要针对近年来流行的基于物理及数据驱动的各种流体动画模拟算法及其应用给出了一个全面的前沿性综述.首先,对传统的基于物理的流体模拟加速方法进行了综述和总结,同时给出了此类方法中各种算法的优劣性分析;其次,对现有的基于数据驱动的多种算法进行了综述和分析.特别地,将现有的数据驱动方法归结为3类,即数据插值法、数据预计算方法和基于深度学习的方法.并且,进一步讨论了基于数据驱动的流体动画模拟算法的几个关键问题以及其研究趋势与方向.     

A Constraint-Based Approach for Visualization and Animation

TRIP systems are tools for visualization and animation. They are based on a constraint-based model of bi-directional translation between abstract data and pictorial data. Using these systems, programmers can visualize abstract data, and animate various algorithms and processes, simply by providing a declarative mapping rule. This paper presents this model for visualization and animation, focusing on the use of constraints, and also presents the TRIP systems with examples of visualization and animation.     

Optimal Algorithms for Finding User Access Sessions from Very Large Web Logs

Although efficient identification of user access sessions from very large web logs is an unavoidable data preparation task for the success of higher level web log mining, little attention has been paid to algorithmic study of this problem. In this paper we consider two types of user access sessions, interval sessions and gap sessions. We design two efficient algorithms for finding respectively those two types of sessions with the help of some proposed structures. We present theoretical analysis of the algorithms and prove that both algorithms have optimal time complexity and certain error-tolerant properties as well. We conduct empirical performance analysis of the algorithms with web logs ranging from 100 megabytes to 500 megabytes. The empirical analysis shows that the algorithms just take several seconds more than the baseline time, i.e., the time needed for reading the web log once sequentially from disk to RAM, testing whether each user access record is valid or not, and writing each valid user access record back to disk. The empirical analysis also shows that our algorithms are substantially faster than the sorting based session finding algorithms. Finally, optimal algorithms for finding user access sessions from distributed web logs are also presented.     

HandPuppet3D: Motion capture and analysis for character animation

Motion capture is a technique of digitally recording the movements of real entities, usually humans. It was originally developed as an analysis tool in biomechanics research, but has grown increasingly important as a source of motion data for computer animation. In this context it has been widely used for both cinema and video games. Hand motion capture and tracking in particular has received a lot of attention because of its critical role in the design of new Human Computer Interaction methods and gesture analysis. One of the main difficulties is the capture of human hand motion. This paper gives an overview of ongoing research “HandPuppet3D” being carried out in collaboration with an animation studio to employ computer vision techniques to develop a prototype desktop system and associated animation process that will allow an animator to control 3D character animation through the use of hand gestures. The eventual goal of the project is to support existing practice by providing a softer, more intuitive, user interface for the animator that improves the productivity of the animation workflow and the quality of the resulting animations. To help achieve this goal the focus has been placed on developing a prototype camera based desktop gesture capture system to capture hand gestures and interpret them in order to generate and control the animation of 3D character models. This will allow an animator to control 3D character animation through the capture and interpretation of hand gestures. Methods will be discussed for motion tracking and capture in 3D animation and in particular that of hand motion tracking and capture. HandPuppet3D aims to enable gesture capture with interpretation of the captured gestures and control of the target 3D animation software. This involves development and testing of a motion analysis system built from algorithms recently developed. We review current software and research methods available in this area and describe our current work.     

Self adaptive animation based on user perspective

In this paper we present a new character animation technique in which the animation adapts itself based on the change in the user’s perspective, so that when the user moves and their point of viewing the animation changes, then the character animation adapts itself in response to that change. The resulting animation, generated in real-time, is a blend of key animations provided a priori by the animator. The blending is done with the help of efficient dual-quaternion transformation blending. The user’s point of view is tracked using either computer vision techniques or a simple user-controlled input modality, such as mouse-based input. This tracked point of view is then used to suitably select the blend of animations. We show a way to author and use such animations in both virtual as well as augmented reality scenarios and demonstrate that it significantly heightens the sense of presence for the users when they interact with such self adaptive animations of virtual characters.     

基于Maya脚本语言的虚拟士兵动画研究

在三维动画制作软件中,传统的人工调整虚拟人动作的工作方式已经不再适合现在的计算机动画制作。针对这一问题,提出了一种采用Maya脚本语言编程来实现人物动画控制的用户界面,在该界面中,动画师可以通过选择按钮移动滑块进行关键帧的设置,从而产生骨架的运动,形成动画。该方法可以提供对制作人物特征有用的工具,使得人物动画的制作更简单。