3D Fabrication of 2D Mechanisms

The success of physics sandbox applications and physics‐based puzzle games is a strong indication that casual users and hobbyists enjoy designing mechanisms, for educational or entertainment purposes. In these applications, a variety of mechanisms are designed by assembling two‐dimensional shapes, creating gears, cranks, cams, and racks. The experience is made enjoyable by the fact that the user does not need to worry about the intricate geometric details that would be necessary to produce a real mechanism. In this paper, we propose to start from such casual designs of mechanisms and turn them into a 3D model that can be printed onto widely available, inexpensive filament based 3D printers. Our intent is to empower the users of such tools with the ability to physically realize their mechanisms and see them operate in the real world. To achieve this goal we tackle several challenges. The input 2D mechanism allows for some parts to overlap during simulation. These overlapping parts have to be resolved into non‐intersecting 3D parts in the real mechanism. We introduce a novel scheme based on the idea of including moving parts into one another whenever possible. This reduces bending stresses on axles compared to previous methods. Our approach supports sliding parts and arbitrarily shaped mechanical parts in the 2D input. The exact 3D shape of the parts is inferred from the 2D input and the simulation of the mechanism, using boolean operations between shapes. The input mechanism is often simply attached to the background. We automatically synthesize a chassis by formulating a topology optimization problem, taking into account the stresses exerted by the mechanism on the chassis through time.     

Direct3D Player性能优化

Direct3D(以下简称D3D)Player是测试显卡驱动所必须的工具软件,其设计并没有考虑到性能,渲染一帧画面通常需要很长时间,给显卡驱动程序的开发带来不便。提出针对D3D Player的性能优化方法,从其运行的机制上研究如何提高其性能,将其分成脚本编译子系统和编译后目标代码执行子系统,最后实现一个优化的D3D Player,并以3D MARK 2001-2005的若干个测试用例来测试D3D Player的优化效果,并比较优化前后的性能变化。     

D5000 VS 500D

主角写真：Peng 21岁 在校大学生 生活写真：科技让我们的生活更有趣。猎奇时尚、新奇创意、对数码产品的有着狂热的爱好。高科技电子玩具、创意影音产品、数码产品、时尚电玩都是我们追逐的目标。     

3D and 2D/3D holograms model

The estimating problem of 3D holograms orientation selectivity on angular, orthogonal, and azimuthal sensitivity parameters is formulated and solved. Tenfold increase of density 3D, 2D/3D holograms in comparison with 2D holograms at given selectivity for ones is shown in theory and experimentally.     

工业CT断层序列图像三维重建的实现

文中对ICT序列断层图像进行三维结构的重建和显示.先对图像进行预处理,去掉空气环,然后再利用Matlab功能强大的函数用体绘制方法进行断层序列图像的三维重建,对某一工业CT机提供的实测数据进行了三维重建,实验结果比较理想.     

工业CT断层序列图像三维重建的实现

文中对ICT序列断层图像进行三维结构的重建和显示。先对图像进行预处理，去掉空气环，然后再利用Matlab功能强大的函数用体绘制方法进行断层序列图像的三维重建，对某一工业CT机提供的实测数据进行了三维重建，实验结果比较理想。     

Hierarchical Representations of 2D/3D Gray-Scale Images and Their 2D/3D Two-Way Conversion

This article proposes G-octree as an extension of G-quadtree to three dimensions. A G-octree reflects in its construction a hierarchy of gray-scale level value homogeneity, as well as a hierarchy of spatial resolution. The article also develops two-way G-quadtree/Goctree conversion procedures based on the algorithms for the binary case. These procedures provide an integrated processing environment for hierarchically represented 2D/3D gray.scale images. We demonstrate our approach with an application to the color coding of macro-autoradiography images taken from rat brains.     

基于单张二维照片的三维姿态计算

通过一张二维照片计算其三维姿态是三维人脸识别和颅像重合中的难点问题。该文主要研究了绕轴的平面旋转、垂直深度旋转和侧深度旋转的姿态计算问题。通过两外眼点间的关系计算平面旋转角度；通过眉间点、鼻下点与颏下点的距离关系计算垂直深度旋转角度；通过鼻下点与两外眼点的角度关系计算侧深度旋转角度。试验证明提出的方法误差小，能够比较准确地计算出三维姿态。     

二维和三维矢量场的可视化

矢量场可视化用来帮助人们直观理解二维和三维矢量场。由于目前的矢量场可视化方法只能展示二维矢量场的方向而不能展示强度,并且对于三维矢量场可视化的效果不太令人满意,因此本文提出了用线积分卷积来实现二维平面矢量场可视化,以及三维空间矢量场可视化的方法。对于线积分卷积中的流线跟踪,利用扩展的Bresenham画线算法的思想,实现了二维平面和三维空间流线的跟踪,并且通过建立一个二维表和三维表来分别存储二维平面矢量场和三维空间矢量场中每个点在流线中的上一个点和下一点的位置,来避免传统流线跟踪方法的冗余计算,提高了效率。对于二维平面矢量场,把线积分卷积的结果和矢量的强度进行加权平均,从而利用输出图像的纹理和颜色,共同来表现矢量场的方向和强度。对于三维空间矢量场,利用体线积分卷积（Volume Line Integral Convolution, Volume LIC）的方法来得到输出体纹理,并且用光线投射的体渲染方法来展示三维空间矢量场。结果显示出本文的方法能够清晰直观的看到二维平面矢量场和三维空间矢量场。     

用户需求感知的D2D视频分发机制

针对目前的D2D多播内容分发机制因冗余传输过高而导致簇头节点能量效率以及系统频谱效率低的问题,提出了一种基于用户需求感知的D2D视频分发机制。通过对用户视频服务请求进行预测,在为服务请求用户分发视频的同时将视频推送给潜在服务用户。首先,根据用户的兴趣、视频的流行度以及用户设备的剩余能量等估算出潜在服务用户接受视频推送的意愿;其次,提出视频分发服务效用值度量来衡量视频分发服务的价值,并对最优化簇头能量效率问题进行建模;最后,提出最优化簇头能量效率的D2D视频分发机制。实验结果表明所提出的D2D视频分发机制相较于传统分发机制其簇头的能量效率及系统吞吐量有着明显的优势。     

由单幅二维灰度图像重构物体表面形状*

鉴于目前很少有论文讨论完整的由单幅二维灰度图像重构物体表面形状的算法,包括它的控制参数的估计及算法的实现,介绍了一种完整的SFS算法.它在考虑自遮掩影响的情况下,有效地估计了SFS算法中涉及的各种控制参数,并引入亮度约束、灰度梯度约束和可积性约束,计算出表面高度和表面向量,实现三维重构.与传统的算法相比,本算法无论是在速度还是在精度方面都达到了比较高的水平,具有一定的应用前景.最后还指出了在MATLAB中实现需要注意的问题.     

Learning 3D Deformation of Animals from 2D Images

Understanding how an animal can deform and articulate is essential for a realistic modification of its 3D model. In this paper, we show that such information can be learned from user‐clicked 2D images and a template 3D model of the target animal. We present a volumetric deformation framework that produces a set of new 3D models by deforming a template 3D model according to a set of user‐clicked images. Our framework is based on a novel locally‐bounded deformation energy, where every local region has its own stiffness value that bounds how much distortion is allowed at that location. We jointly learn the local stiffness bounds as we deform the template 3D mesh to match each user‐clicked image. We show that this seemingly complex task can be solved as a sequence of convex optimization problems. We demonstrate the effectiveness of our approach on cats and horses, which are highly deformable and articulated animals. Our framework produces new 3D models of animals that are significantly more plausible than methods without learned stiffness.     

多巴胺D1和D5受体的同源模建研究

多巴胺与其受体组成的多巴胺系统与许多疾病有关,比如帕金森病、精神分裂症等.但是,多巴胺受体的晶体结构一直没有得到解析,给相关疾病的药物开发带来难度.本文采用同源模建的方法,用与D1和D5受体同源性达到34.6%的肾上腺素能受体2vt4作为模板,构建D1和D5受体的三维模型.结果表明:经过优化和动力学模拟,然后用PROCHECK、ERRAT及PROSA程序进行构象和能量的评价,用多巴胺进行对接验证,证明模建的D1受体和D5受体模型是合理的、可靠的.     

Robust registration of 2D and 3D point sets

This paper introduces a new method of registering point sets. The registration error is directly minimized using general-purpose non-linear optimization (the Levenberg–Marquardt algorithm). The surprising conclusion of the paper is that this technique is comparable in speed to the special-purpose Iterated Closest Point algorithm, which is most commonly used for this task. Because the routine directly minimizes an energy function, it is easy to extend it to incorporate robust estimation via a Huber kernel, yielding a basin of convergence that is many times wider than existing techniques. Finally, we introduce a data structure for the minimization based on the chamfer distance transform, which yields an algorithm that is both faster and more robust than previously described methods.     

基于D3D的三维虚拟人运动显示

开发了一套基于Direct 3D技术的应用程序开发包DXVHSDK，它可以在虚拟环境中载入、驱动并显示一个或多个三维虚拟人，具有绘制速度快、可靠性高、可扩展性强等优点，能够灵活地驱动虚拟角色完成各种复杂的运动和操作，可以广泛应用于仿真、娱乐、智能人机交互等领域．在DXVHSDK的基础上，还开发了一个可以控制虚拟人运动的原型系统．     

Curvature approximation of 3D manifolds in 4D space

A method for the approximation of the three principal curvatures at points on a discretized, triangulated 3D manifold in 4D space (referred to as 3-surface) is presented. The approximation scheme is based on the fact that a parametric 3-surface can locally be approximated by the graph of a trivariate function. Using a local coordinate system, a least square polynomial approximation is constructed for the estimation of the principal curvatures at each 3-surface point. Curvature is extremely useful for the analysis of qualitative characteristics of surfaces. The technique presented is an example of extending existing surface interrogation methods to multivariate data. Such a generalization is valuable for scientific visualization.     

1D selection of 2D objects in head-worn displays

In current desktop user interfaces, selection is usually accomplished easily with a mouse or a similar two-dimensional locator. In wearable computing, however, controlling two dimensions simultaneously gets significantly harder: a change in one dimension results easily in an undesired change in the other dimension as well when the user is occupied with a parallel task – such as walking. We present a way to overcome this problem by applying one-dimensional selection for graphical user interfaces in head-worn displays. Our new interaction technique allows a wearable computer user to perform object selection tasks easily and accurately. The technique is based on a visible circle on the screen. The user controls the circle, altering its radius with a one-dimensional valuator. The midpoint of the circle is in the middle of the screen. The object currently on the perimeter of the circle is highlighted and can be selected. Our preliminary usability evaluation, applying our custom evaluation method designed especially for walking users, indicates that the proposed technique is usable also when walking.     

态势可视化的二三维联动技术

研究了主流的二维和三维显示技术,WGS84坐标和墨卡托投影坐标变换方法,消息中间件和AAR存档系统等态势可视化技术,提出了数据库API网关.设计并实现了一种二三维联动的态势可视化系统,采用消息中间件同步仿真过程信息,用数据库API网关统一管理实体的二三维模型,用AAR存档系统记录和回放仿真过程,经测试,态势可视化系统能够正确的,有效的完成仿真功能,且二维和三维显示部分显示的态势是联动的.