纹理映射

The accelerated algorithm of volume rendering based on textures mapping and the wavelet-based multiresolution volume rendering in network are performed by using OpenGL 3D visualization technique. From the point of view of computer graphics, 3D visualization mechanism of volume rendering based on OpenGL textures mapping is studied, including modelview transformation, projection transformation, perspective division, viewport transformation and the ways to embed textures mapping and blending in above four transformations.

利用OpenGL三维可视化技术实现了本文所提出的基于纹理映射的体绘制加速算法和网络环境下基于小波的体数据的多分辨率体绘制，并从计算机图形学的角度，研究了基于OpenGL纹理映射技术的体绘制的三维可视化流程，包括OpenGL的模视变换、投影变换、透视除法、视区变换，以及纹理的定义、映射与融合等步骤在上述四个变换中的嵌入方法。

By the algorithm, the surfaces are first divided into a series of mapping areas and synthesis areas using the constraints of the triangles' normal and texture attributes. Then the mapping areas are textured by harmonic mapping from the 2D mapping sample, by a patch-based synthesis method. Finally, the synthesis areas are textured by a triangle-based synthesis method.

首先以三角形法向量、切向矢量与纹理尺度为约束，将三角网格曲面分割为一系列映射区与合成区；然后用基于块的平面纹理合成方法生成大面积样图，用调和映射方法对映射区进行纹理映射；最后采用基于三角块的合成方法生成合成区纹理。

Based on the summarizing of the exiting algorithms of the texture mapping and antialiasing, this paper goes deeply into the basic theory and processing of texture mapping. The texture compress algorithm which can satisfy the need of the memory and time is given for the stochastic sampling in the inverse texture mapping; the geometry transformation in the texture mapping are discussed and the concepts of the unitary parametrization and the patch parametrization is proposed, some kinds of the unitary parametrization methods of parametric surfaces and the geometry transformation in the patch parametrization are also presented; in order to solve the aliasing in the parametrization of intermediate surface-sphere in two-part texture mapping, an area-preserving transformation is presented also; to improve the quality of the graph the aliasing in the texture mapping is analyzed from the aspect of signal process, and the modified summed-area tables algorithms is proposed; the distortion of the scanline conversion algorithms under perspective transformation is analyzed and the proper interpolation algorithm is presented so the aliasing problem of the polyhedral object after the unitary parametrization is efficiently solved.

本文在总结现有的纹理映射和反走样算法的基础上，深入研究了纹理映射的基本原理与过程，根据反向纹理映射对纹理随机采样的特殊要求，提出了一种可满足存储空间和寻址时间的纹理压缩存储算法；通过对纹理映射中几何变换理论的进一步深入探讨，提出了整体参数化和面片参数化的概念，并给出了参数化曲面的各种整体参数化方法和面片参数化的几何变换形式；针对现有的两步映射算法所存在的中间曲面—球面的参数化问题，提出一种等积映射方法，较好地实现了由非参数化面片拼接而成的多面体表面的纹理映射；从信号采样的角度深入分析了纹理映射中走样产生的原因，提出了改进的区域求和表算法，使图形生成的效果有所提高；还分析了一般的扫描线算法在透视变换中所存在的问题，提出了一种正确的插值算法，从而解决了整体参数化后多面体表面纹理映射的几何变形问题。

Two-dimensional texture mappings are summarized in this paper including Catmull algorithm and Blinn algorithm, two-step texture mapping, environment mapping and bump mapping. Moreover, a new method of regional texture mapping based on intermediate surface is presented and a new algorithm is promoted to reduce texture distortion in the process of mapping onto the sphere surface.

在二维纹理方面，本文讨论了适用于参数曲面的Catmull算法与Blinn算法，适用于一般曲面的两步纹理映射技术，现已广为应用的环境纹理映射技术及凸包纹理映射技术，还分析了纹理映射的几种快速反走样技术。

For 3D dressing rendering of fabric, the paper states the theory of 2D texture mapping onto 3D surface. And then, the mapping relations of fabric texture toward garment surface and shading/texturing model are studied, the graphic transformations and texture mip-mapping technology, which concern the 3D dressing display, are put forward too.

针对于织物三维着装效果的展示，论文介绍了纹理映射技术的原理，研究了织物纹理对服装曲面的纹理映射关系和纹理光照模型，并对涉及三维着装图形显示的图形变换和纹理细化技术进行了探讨。

For regular topology surface, intermediate surface local texture mapping are used; for irregular topology surface, subdivision surface local texture mapping are used. So different topology surface using different texture mapping methods can solve the contradiction between texture effect and processing speed when they are dealt with by single method. The three judge conditions of texture distortion in the process of mapping onto the sphere surface are discussed and the exiting algorithms of mapping are analyzed, the new algorithms of mapping onto the sphere surface are presented. In order to enhance the realistic of graphics, a new function of wood texture is presented. OpenGL is also introduced in this papers and some realization examples of texture mapping based on OpenGL under the environment of VC++ and POV-RAY are presented in some chapters.

对于简单拓扑表面，利用改进的两步纹理映射，对于复杂拓扑表面利用新的面片分割算法，初步解决了颜色纹理中速度与走样之间的矛盾；通过对球面纹理时纹理不变形的三个判断条件的研究，分析了现在各种球面纹理映射算法，并在此基础上提出了一种基于等面积的半球面纹理映射算法，明显减少了球面纹理的纹理变形；针对现有的木纹纹理中，两种表示木纹的颜色差距表现出的颜色突变问题进行研究，提出对这两种颜色进行线性插值或二次插值，使生成的木纹纹理颜色更加连续，更加逼真；在VC++环境下，通过调用Open GL的图形库及在Pov-Ray软件环境下，实现了参数化纹理、球面纹理、凹凸纹理及木纹纹理等各种算法。

This process is as follows: applying projective transformation on the plane, using interpolation method to acquired texture, and then mapping it on the model.

讨论了如何纠正平面纹理的透视变形，及其相应的纹理映射，其过程是在两视图重建的基础上，对原平面进行投影变换，并用插值方法获得纹理，从而映射到模型上。

Experiments in texture mapping show that the proposed method has better performance than some popular parameterization methods.

将该方法应用于纹理映射中的数值实验表明，其比常见的几种参数化方法具有更好的纹理映射效果。

Based on the summarizing of the algorithms of subdivision surface by Catmull and two-part texture mappings by Biers, this papers goes deeply into features of local texture mapping and the exiting problem, two kinds of local texture mapping methods are presented according to different topology surface.

本文在总结了Catmull的分割面片算法和Bier等的两步纹理映射算法基础上，深入研究了局部纹理映射的特点及目前存在的问题，提出了针对不同拓扑关系表面的两种局部纹理映射算法。

Based on the summarizing of the algorithms of subdivision surface by Catmull and two-part texture mappings by Biers, this paper goes deeply into the realization algorithm of the Texture Mapping on the plane, quadratic surface and NURBS surface and the algorithm of the texture mapping when the plane and the general parametric surface are the optimal intermediate surfaces.

本文在研究和总结了Catmull的分割面片算法和Bier等两步纹理映射算法的基础上，讨论了平面和一般参数曲面作为中间曲面的纹理映射方法。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。