Interactive Indirect Illumination Using Voxel Cone Tracing

Indirect illumination is an important element for realistic image synthesis, but its computation is expensive and highly dependent on the complexity of the scene and of the BRDF of the involved surfaces. While off‐line computation and pre‐baking can be acceptable for some cases, many applications (games, simulators, etc.) require real‐time or interactive approaches to evaluate indirect illumination. We present a novel algorithm to compute indirect lighting in real‐time that avoids costly precomputation steps and is not restricted to low‐frequency illumination. It is based on a hierarchical voxel octree representation generated and updated on the fly from a regular scene mesh coupled with an approximate voxel cone tracing that allows for a fast estimation of the visibility and incoming energy. Our approach can manage two light bounces for both Lambertian and glossy materials at interactive framerates (25–70FPS). It exhibits an almost scene‐independent performance and can handle complex scenes with dynamic content thanks to an interactive octree‐voxelization scheme. In addition, we demonstrate that our voxel cone tracing can be used to efficiently estimate Ambient Occlusion.     

木制椅的情感分析

结合时代的变迁,关注各款新式椅子的诞生,分析木制椅给人们带来的情感因素,提出合理地利用材料性能,选择合适的加工工艺,创造出更美好的椅子造型,给人更惬意的精神享受。     

Human Body Model Acquisition and Tracking Using Voxel Data

We present an integrated system for automatic acquisition of the human body model and motion tracking using input from multiple synchronized video streams. The video frames are segmented and the 3D voxel reconstructions of the human body shape in each frame are computed from the foreground silhouettes. These reconstructions are then used as input to the model acquisition and tracking algorithms.The human body model consists of ellipsoids and cylinders and is described using the twists framework resulting in a non-redundant set of model parameters. Model acquisition starts with a simple body part localization procedure based on template fitting and growing, which uses prior knowledge of average body part shapes and dimensions. The initial model is then refined using a Bayesian network that imposes human body proportions onto the body part size estimates. The tracker is an extended Kalman filter that estimates model parameters based on the measurements made on the labeled voxel data. A voxel labeling procedure that handles large frame-to-frame displacements was designed resulting in very robust tracking performance.Extensive evaluation shows that the system performs very reliably on sequences that include different types of motion such as walking, sitting, dancing, running and jumping and people of very different body sizes, from a nine year old girl to a tall adult male.     

基于软传感器的信息融合

为了利用”凝视视觉几何约束”的信息来确定移动机器人的位置和方位角,就需要解决数据融合的问题。”几何约束”不是来自真实传感器的直接可测量的数据,这种特殊形式的信息不能被直接融合。为此目的,该文提出了一种融合特殊形式信息的新途径,也即利用”软传感器”的方法来融合来自”几何约束”的信息。软传感器的输出与其它真实传感器的输出一起经过扩展信息滤波器最终实现融合。文中最后提供了利用该方法进行移动机器人定位的计算机仿真例子。仿真结果表明了软传感器信息融合方法的可行性和有效性。软传感器可以广泛应用在很多类似的信息融合问题中。     

现代木艺与公共空间

现代木艺作为公共空间中的主要媒介之一,在公共空间中具有重要作用。本文以公共空间中的现代木艺为切入点,从现代木质壁画、木质雕塑、木质隔断介入公共空间来论述现代木艺与公共空间的关系。     

Tracing a ray through uniformly subdividedn-dimensional space

Finding the cells intersected by a ray in a uniformly subdivided space is a technique used in accelerated ray tracing and also other computer graphics applications. A related problem is that of finding the sequence of grid points in a 3D voxel space, which best approximates a given line. This paper examines earch of these problems, introduces a unifying approach and provides a generalisation of previous algorithms.Written while on sabbatical leave from Department of Computer Science, QMW University of London, Mile End Road, London E1 4NS, UK     

从现代室内装饰设计谈莆田木雕的发展方向

作者在对莆田木雕研究的基础上,结合当前室内软装的发展趋势,为莆田木雕找出一个新的发展突破点——装饰木雕,并从题材、形式、构图、风格等几个方面阐述了莆田木雕装饰木雕的发展趋势。     

人工神经网络在木材损伤识别中的应用

利用人工神经网络(ANN)对含有不同缺陷程度的木材进行了定性和定量解析.通过选择合理的神经网络结构,建立有效的训练样本集,确定合理的参数及训练方法,对3种不同缺陷类型木材进行了解析,考察了网络的泛化能力.结果表明:该网络能够对不同缺陷程度的木材进行准确地识别,而且本研究为人工神经网络在木材缺陷损伤的定性和定量分析方面提供了一种有效的方法.     

基于Otsu算法的木材缺陷图像分割

提出了基于Ostu算法的木材缺陷图像分割.该方法借助于二维中值滤波器对木材图像进行平滑处理,将平滑过的图像用Otsu算法确定图像分割阈值.实验结果表明,该方法可以有效地实现木材表面缺陷图像分割.     

Collaborative Filtering Using a Regression-Based Approach

The task of collaborative filtering is to predict the preferences of an active user for unseen items given preferences of other users. These preferences are typically expressed as numerical ratings. In this paper, we propose a novel regression-based approach that first learns a number of experts describing relationships in ratings between pairs of items. Based on ratings provided by an active user for some of the items, the experts are combined by using statistical methods to predict the users preferences for the remaining items. The approach was designed to efficiently address the problem of data sparsity and prediction latency that characterise collaborative filtering. Extensive experiments on Eachmovie and Jester benchmark collaborative filtering data show that the proposed regression-based approach achieves improved accuracy and is orders of magnitude faster than the popular neighbour-based alternative. The difference in accuracy was more evident when the number of ratings provided by an active user was small, as is common for real-life recommendation systems. Additional benefits were observed in predicting items with large rating variability. To provide a more detailed characterisation of the proposed algorithm, additional experiments were performed on synthetic data with second-order statistics similar to that of the Eachmovie data. Strong experimental evidence was obtained that the proposed approach can be applied to data over a large range of sparsity scenarios and is superior to non-personalised predictors even when ratings data are very sparse.     

The modelling of large waterfalls using string texture

Particle systems have been extensively used for modelling fluid flow. But if a large number of particles are required, this can lead to unreasonably large amounts of memory usage. This is because the position and velocity is stored explicitly for each particle. Solid texture, on the other hand, stores parameters implicitly, by means of addressing small look-up tables. This paper presents a method of implicitly storing particles, and illustrates its use with the modelling of large waterfalls.     

一种近似周期性纹理的合成方法

纹理合成是近年来图形图像处理领域的研究热点之一,该文针对基于块的纹理合成方法合成效果与采样块的尺度密切相关的问题,根据近似周期性纹理自身的特点,结合基于块的纹理合成方法给出适合此类纹理的一种合成方法。由于周期性纹理的纹元是以周期为单位的纹理块,该文试图对周期性纹理图像进行方向滤波后找出纹理的周期,然后以周期尺度为采样块的大小和采样间距,进行纹理合成。该文方法对严格周期性纹理及近似周期性纹理合成效果良好。     

基于颜色特征对木材分级的研究

给出几种基于颜色特征木材的分级算法,这几种方法通过主颜色特征,分别利用神经网络中的RBF网络、K-近邻和最近邻对木材样本图像进行处理,然后进行分类.木材样本图像是通过对木材加工处理采集而得到的;主颜色特征是反映一幅图像的基本面貌,并通过HSV颜色模型、量化、颜色直方图和绝对距离而得到的.选取3种主颜色方案数据,经过Matlab7.0平台进行程序设计,对木材样本图像数据进行训练和测试,并加以验证.实验结果表明,这几种方法能够较好地解决木材分级的问题.     

湖南民间建筑木雕装饰特征研究

湖南民间建筑木雕,在其自身发展的历史进程中,以优秀的湖湘文化为背景,形成了自己独特的风格。文章从湖南木雕的雕刻、造型、漆饰装饰等的艺术表现形式等方面对湖南民间建筑木雕的装饰特征进行了研究。     

Texture evolution: 3D texture synthesis from single 2D growable texture pattern

An efficient model-independent 3D texture synthesis algorithm based on texture growing and texture turbulence is presented to create vivid 3D solid texture from a single 2D growable texture pattern. Given a 2D texture pattern of some growable material, our technique is able to create an anisotropic 3D volumetric texture cube to simulate the evolution of the material in 3D. An effective tiling scheme is designed to save computation and storage costs. Target objects are directly dipped into the synthesized 3D texture volume to generate creative, sculpture-like models that can be visualized with interactive speed. Our method is conceptually intuitive, computationally fast, and storage efficient compared with other solid texturing methods. As opposed to conventional 2D texture mapping work on polygonal surfaces, our approach is capable of decorating 3D point-rendering systems seamlessly. Furthermore, our combination of texture turbulence and texture growing techniques provides an attractive way to synthesize and tile natural 2D texture patterns, or generate simple but interesting motion textures.     

利用光栅操作模拟图形动画

文章介绍了利用VB的API函数处理位图的过程,使图形动画显得更加逼真和生动。     

Learning Complex Tasks Using a Stepwise Approach

This paper explores a stepwise learning approach based on a system's decomposition into functional subsystems. Two case studies are examined: a visually guided robot that learns to track a maneuvering object, and a robot that learns to use the information from a force sensor in order to put a peg into a hole. These two applications show the features and advantages of the proposed approach: i) the subsystems naturally arise as functional components of the hardware and software; ii) these subsystems are building blocks of the robot behavior and can be combined in several ways for performing various tasks; iii) this decomposition makes it easier to check the performances and detect the cause of a malfunction; iv) only those subsystems for which a satisfactory solution is not available need to be learned; v) the strategy proposed for coordinating the optimization of all subsystems ensures an improvement at the task-level; vi) the overall system's behavior is significantly improved by the stepwise learning approach.     

基于滤波器组的纹理分类研究

论述了基于滤波器组的纹理分类方法。该方法首先利用滤波器组对纹理进行滤波，纹理特征是用滤波器输出的统计值表示的；然后用这些特征向量进行纹理分类研究，分类主要利用了简单（naive）Bayes分类方法和最大加权相关树分类方法。实验显示，最大加权相关树分类方法的效果是较好的。     

Using a Formalized Approach to Digital Investigation

Peter StephensonRecently I was in the audience for the presentation of a case study of an investigation into the theft of a large number of credit cards from a credit card clearing house. The discussion showed clearly that the investigation was not, by any standards, a success. The clearing house had such terrible security measures in place that the attack had no barriers to prevent success and the contractor investigative team demonstrated no structured process in its investigation.