基于VRML的中国手语三维显示

手语合成的目的是由计算机自动生成文本句子对应的手语，是智能人机接口研究的一个极具挑战性的课题。手语显示是手语合成过程中非常关键的一步，其任务是在文本句子转换为手语码后，将手语码逼真地显示成虚拟人手语运动。介绍了研究中国手语合成时提出的一种基于VRML的三维虚拟人姿态显示方法和连续中国聋人手语显示方法。该方法不仅可以显示逼真的虚拟人合成手语，而且具有很好的通用性，为网络环境中实现不同人体模型的手语表达与传输打下了基础。     

Learned Models for Estimation of Rigid and Articulated Human Motion from Stationary or Moving Camera

We propose an approach for modeling, measurement and tracking of rigid and articulated motion as viewed from a stationary or moving camera. We first propose an approach for learning temporal-flow models from exemplar image sequences. The temporal-flow models are represented as a set of orthogonal temporal-flow bases that are learned using principal component analysis of instantaneous flow measurements. Spatial constraints on the temporal-flow are then incorporated to model the movement of regions of rigid or articulated objects. These spatio-temporal flow models are subsequently used as the basis for simultaneous measurement and tracking of brightness motion in image sequences. Then we address the problem of estimating composite independent object and camera image motions. We employ the spatio-temporal flow models learned through observing typical movements of the object from a stationary camera to decompose image motion into independent object and camera motions. The performance of the algorithms is demonstrated on several long image sequences of rigid and articulated bodies in motion.     

基于视频的实时自动人体高度测量

怎样从视频出发准确实时地测量场景中运动人体的高度? 针对此问题, 本文提出了一种自动实时的人体高度测量方法. 该方法首先在视频序列中的每帧图像上提取一种新的头部特征点以及一种新的脚部特征点, 然后根据这些特征点建立约束方程求出近似的人体高度, 并同时在视频序列中跟踪双脚. 最后基于获得的双脚跟踪结果, 引入一条关于特征点所对应空间点的几何约束以进一步优化测量结果. 与过去的许多测量方法相比, 本文方法有效地利用了视频序列中包含的运动信息, 有较强的鲁棒性和较高的测量精度, 既能有效地处理透视镜头下的视频又能处理鱼眼镜头下的视频, 而且计算量很低, 可以实现实时测量. 实验结果验证了本文算法的有效性和实时性.     

Recursive Formalism with a Minimal Dynamic Parameterization for the Identification and Simulation of Multibody Systems. Application to the Human Body

This paper presents a multibody formalism using a minimal set of dynamicalparameters, based on the barycentric approach. Using relative jointcoordinates, we show that it is possible to generate recursively the inverseand direct dynamics in terms of this minimal set, rather than using theclassical ones (mass, centre of mass and inertia matrix). More thanproviding a very compact scheme in terms of flops, the proposed formalism,in which the independent dynamical parameters appear linearly, is a precioustool for identification purpose; indeed, the recursive nature of theformalism and its symbolic implementation allows us to deal with very large models, such as the human body for instance. The approach is then applied to the identification of some of the human body's dynamical parameters, on the basis of a trajectory issuing from a volleyball typical movement.     

一种新的人眼视觉运动认知特性实验分析方法

视觉感知过程源于对象自身的大范围拓扑性质,而场景对象发生运动状态变化时,其所在空间的大范围拓扑关系也将随之改变。为探索大范围拓扑性质和运动性质同时改变时人眼视觉的认知优先特性,基于虚拟现实技术及眼动跟踪技术,通过构建虚拟驾驶及眼动轨迹分析实验平台,结合拓扑复杂度和空间拓扑关系概念分别探讨二维和三维空间中人眼视知觉对物体运动的认知特性。在此基础上,采用响应面分析方法设计场景中自变量因子的随机实验数值,通过可视化方法对比多组认知场景的无感反馈眼动监测结果。实验结果表明,在Tobii眼动仪采集的545个眼动数据中,发生在运动物体上的数据有516个,相比于物体自身属性的大范围拓扑性质变化,人眼视知觉过程更优先识别物体运动的大范围空间拓扑关系变化。该运动认知优先特性为可靠人工智能驾驶中的视觉注视预测技术提供了新的研究思路,同时验证了所提实验分析方法的有效性。     

Using Human Perceptual Categories for Content-Based Retrieval from a Medical Image Database

It is often difficult to come up with a well-principled approach to the selection of low-level features for characterizing images for content-based retrieval. This is particularly true for medical imagery, where gross characterizations on the basis of color and other global properties do not work. An alternative for medical imagery consists of the “scattershot” approach that first extracts a large number of features from an image and then reduces the dimensionality of the feature space by applying a feature selection algorithm such as the Sequential Forward Selection method.This contribution presents a better alternative to initial feature extraction for medical imagery. The proposed new approach consists of (i) eliciting from the domain experts (physicians, in our case) the perceptual categories they use to recognize diseases in images; (ii) applying a suite of operators to the images to detect the presence or the absence of these perceptual categories; (iii) ascertaining the discriminatory power of the perceptual categories through statistical testing; and, finally, (iv) devising a retrieval algorithm using the perceptual categories. In this paper we will present our proposed approach for the domain of high-resolution computed tomography (HRCT) images of the lung. Our empirical evaluation shows that feature extraction based on physicians' perceptual categories achieves significantly higher retrieval precision than the traditional scattershot approach. Moreover, the use of perceptually based features gives the system the ability to provide an explanation for its retrieval decisions, thereby instilling more confidence in its users.