An image-based texture mapping technique for apparel products exhibition and interior design

In this paper, we propose an image-based texture mapping technique for textile products exhibition that does not require geometric representation of 3D models. Under this technique, a texture grid is built interactively for a target area in an original image. This grid acts as the intermediate space between planar space and texture space. The texture coordinate for each pixel in the target area can be calculated based on this grid, and the 3D effect can be successfully realized by further fine adjustment of the grid. This technique can be applied in apparel products exhibition and interior design.     

A novel constrained texture mapping method based on harmonic map

In this paper, we present a novel constrained texture mapping method based on the harmonic map. We first project the surface of a 3D model on a planar domain by an angle-based-flattening technique and perform a parametrization. The user then specifies interactively the constraints between the selected feature points on the parametric domain of the 3D model and the corresponding pixels on the texture image; the texture coordinates of other sample points on the 3D model are determined based on harmonic mapping between the parametric domain of the model and the texture image; finally we apply an adaptive local mapping refinement to improve the rendering result in real-time. Compared with other interactive methods, our method provides an analytically accurate solution to the problem, and the energy minimization characteristic of the harmonic map reduces the potential distortion that may result in the constrained texture mapping. Experimental data demonstrate good rendering effects generated by the presented algorithm.     

TCPHA:一个新型的高性能基于内容调度系统

目前Web服务器集群的调度技术中,基于内容的调度是一种主流的调度技术,有很多的优势。但目前流行的基于内容的调度系统普遍存在系统可扩展性差,调度器性能瓶颈问题,而不能充分发挥基于内容调度的优势。该文研究实现了一种新型的基于内容调度系统TCPHA,它在操作系统内核工作,实现了一些最新的技术,如TCP Handoff技术、动态IP Tunnel技术、ARP过滤技术等。性能测试表明,相对于传统的基于内容调度系统,TCPHA有着更高的性能。     

基于内容感知和团购策略的云视频分发网络

云视频分发网络(Cloud Video Delivery Networks,CVDNs)将云存储技术应用于视频分发网络(Video Deli-very Networks,VDNs),能够以较低的成本为用户提供高质量的视频分发服务,如在线视频、在线直播等。然而,当前的云视频分发机制对视频内容分类以及用户协作的考虑较少。如何结合视频内容分类以及用户协作关系来进一步节省用户的购买成本,是一个极具挑战性的问题。从用户角度提出了一种内容感知的团购(Content-aware and Group-buying,CG)策略,对不同的视频内容进行分类定价,允许用户组成团购联盟后购买视频内容。然后,通过定义成本公式和用户购买量约束、单用户成本约束,将CG问题描述为线性规划问题并用GLPK工具对其进行求解。实验结果表明,在内容感知条件下的团购策略可以有效地降低用户成本。     

Texture mapping and distortion in digital graphics

Texture mapping is a method commonly used to increase the visual complexity of computer generated images while maintaining simplicity in the underlying geometric models. Texture maps are generally defined in two dimensional space; thus, a primary problem when applying textures to objects is determining a mapping transformation from the three dimensional space of the object to the two dimensional space of the map. A method for mapping complex polygonal geometries is presented. The algorithmunfolds the object polygon by polygon and projects the texture map onto the resulting two dimensional geometry. Enhancements to the basic unfolding algorithm either (1) control the location of map distorition introduced at areas of severe curvature or (2) average distortions over a larger area.     

基于两步法的交互式纹理映射研究

两步纹理映射方法将映射过程分解为S映射与O映射两步进行.针对两步纹理映射方法研究中复杂物体表面纹理映射时出现的变形问题,采用B样条曲面代替简单的中间映射媒介,用它近似地包裹在三维物体的外表面,将纹理通过某种方式映射到曲面上实现参数化.基于两步映射方法提出了一种交互式纹理映射的算法.该算法允许用户交互选择贴图范围,通过控制B样条曲面实现对映射效果的调整.实验结果表明,该算法可显著提高纹理映射质量,纹理贴图效果良好.     

An improved description method of the bumpy texture

Bump mapping is a texture-based rendering approach for simulating surface details to make its illumination results have three-dimensional effects. The bumpy properties of an object are determined by height maps. But in the process of generating height maps, a problem arises, i.e. to get a correct value of the pixel height, empirical data should be calculated repeatedly, which proves very complicated, and meanwhile the realistic rendering effect is reduced, because the bumpy property is exaggerated in the height map. Therefore, in this paper, we present a method for describing the details of the bumpy texture, where a new concept “bumpy map” is introduced to replace the height map. Experimental results demonstrate that the bumpy details produced by the “bumpy map” are more consistent with the original bumpy texture than by the method of height map. Supported partially by the National Natural Science Foundation of China (Grant Nos. 60533030, 60825203, 60572104), National High-Tech Research & Development Program of China (Grant No.2006AA01Z317), Science and Technology Development Program of Education Commission in Beijing (Grant No. KM200710005017)     

基于面部特征约束的人脸纹理映射及变形

将一幅人脸图像（称为源图像）映射到另一幅人脸图像（称为目标图像）上,从而实现人脸图像的变形并达到某种特殊效果的表现要求。其中,一个最关键的问题是保持两幅人脸中器官特征的约束映射。提出一种技术策略,可以有效实现这种映射效果。利用人脸特征检测算法检测出源人脸和目标人脸的特征点;基于特征点,利用Delaunay三角剖分的方法将目标人脸转化为三角网格;采用调和映射的方法计算得出所有网格点在源人脸图像中的对应坐标;在获得网格点纹理坐标后,就可以实现源人脸到目标人脸的映射。实验表明,该方法可以实现任意人脸间的映射,并能较好地保持人脸五官间的映射关系。     

Edge-preserving texture filtering for real-time rendering

Texture filtering is essential in enhancing the visual quality of real-time rendering. Conventional schemes do not consider the characteristics of texture content, thus the sharpness of edges in texture images cannot be retained. This paper proposes a novel texture-filtering algorithm, which consists of edge-preserving interpolation and edge-preserving MIP-map prefiltering. The memory bandwidth requirement is kept the same as in conventional schemes by dynamically adjusting the interpolation kernel. Hardware implementation is also provided to show the real-time processing capability. Published online: 28 January 2003     

纹理映射技术中Mip-Map的研究

在图形处理中,一个重要的研究方向是图形的真实感问题。纹理映射是高质量图像生成的一种重要技术,使三维图形更富真实感。Mip-Map纹理映射技术中,常常用一个正方形来近似表示象素在纹理空间的投影,但是像素投影并非正方形,是各向异性的,所以这种方法不符合反走样的要求,本文提出改进d值算法和长方形区域采样两种改进的算法来实现反走样。     

Textural filters based on the texture spectrum

Conventional digital filtering techniques, based on classical Fourier analysis (that is, low-pass, high-pass and band-pass), are widely used in digital image processing. Unsatisfaction may be encountered when applying these filters to texture analysis of images, where one needs some specific spatial filters which are able to transform an image in the sense of texture rather than the spectral properties. Such textural filters can be designed in the texture spectrum domain and they are of interest for texture analysis. An example is given in this paper, and has been applied to four of Brodatz's natural images. The result shows a promising potential of the texture spectrum for designing textural filters.     

基于OSG的规则多面体重构和纹理映射技术

对物体进行纹理贴图的主要方法是将纹理坐标同物体表面顶点坐标建立关联,但是在建模软件之外由于没有物体的顶点坐标信息,要实现纹理映射相当困难.在OSG的基础上,采用重构规则物体表面的方法实现了物体的按面纹理映射,并得到了预期的效果.     

纹理映射在模型优化中的应用

三维模型的构建是虚拟现实及视景仿真系统中最基本、最重要的组成部分之一。构建三维模型需考虑到场景浏览的真实感与实时性,因而需要建立一个最优化的可视化模型。本文比较了在虚拟现实系统中模型优化的方法,采用了纹理映射代替多边形建模创建高效真实感模型的优化手段,着重介绍了颜色纹理和凹凸纹理的相关理论和方法,并应用于视景仿真系统中,极大的提高了实时性,并保证了真实感。     

Automatic defect detection of texture surface with an efficient texture removal network

Automated defect inspection of texture surface is still a challenging task in the industrial automation field due to the tremendous changes in the appearance of various surface textures. We present a simple but powerful image transformation network to remove textures and highlight defects at full resolution. The simple full convolution network consists only of 3 × 3 regular convolution and several dilated convolution blocks, which makes it compact and able to capture multi-scale features effectively. To further improve the ability of the network to suppress texture and highlight defects, a polynomial loss function combining perceptual loss, structural similarity loss and image gradient loss is proposed. In addition, a semi-automatic annotation method mainly composed of wavelet transform and relative total variation is designed to generate a data set of image pairs containing the original texture image and the desired texture removal image. We conducted experiments on a milled metal surface defect dataset and an open data set containing various textured backgrounds to evaluate the performance of our method. Compared with other convolutional neural network approaches, the results demonstrate the superiority of the proposed method. The method has been applied to the surface defect online detection system of an aluminum ingot milling production line, which effectively improves the surface inspection efficiency and product quality.     

一种利用附加纹理信息进行三维喷绘的方法

针对三维透视投影视图中对三维物体表面纹理直接进行喷绘,以获得复杂纹理图这一计算机图形交互技术这一新问题,研究了一种将纹理图的象素位置信息转换成彩色信息,然后利用纹理映射将纹理坐标连同该点上的颜色值一起传递到与屏幕象素对应的可见点上的方法,其中颜色值依该点处的入射光线方向和表面法向被进一步转换为光强值,而纹理坐标则被解码后还原成与该可见点对应的纹理坐标,被存入信息缓冲器中,供以后使用,通过解码,可根据屏幕点直接得到纹理象素点的坐标,经过算法优化,实现了对三维物体表面纹理的实时喷绘;同时阐述了在三维图象生成技术中使用附加纹理信息的应用实例以及相关定义。     

一种基于表面积比例的地形纹理贴图算法

三维地形模型和纹理贴图都是计算机图形学领域的热点课题,他们也同时被广泛运用于计算机仿真.然而,对于三维地形纹理贴图,目前还没有高效准确的实用算法.文中参考了国内外的研究成果,分析和比较了现有的常用贴图方法,提出了一种新型地形纹理贴图算法.该算法以地形表面积比例作为纹理分割标准,使用分治法划分纹理空间,对于用高度图表示的网格地形,计算快速,并且实现了理想的地形贴图效果,有效减少了拉伸失真,是一种适合实际应用的地形纹理贴图算法.     

基于二维纹理映射的镜面反射加速绘制

针对物体表面镜面反射现象的绘制,提出了一种新的基于二维纹理映射技术的加速算法。将具有镜面反射表达式的Phong模型分解成多个简单的数学函数,预先离散采样计算后作为纹理对象传给显卡。使用OpenGL多重纹理技术,将每个纹理对象放入相应的纹理单元,分别设置其组合函数,将多个纹理的运算组合起来。将三角片顶点坐标及多组纹理坐标传入,从而实现了物体镜面反射现象的实时绘制。实验结果表明,该算法大大提高了绘制的性能。