【作者】 江巨浪；

【导师】 张佑生；

【作者基本信息】 合肥工业大学 ， 计算机应用技术， 2006， 博士

【摘要】 曲面纹理绘制技术是绘制真实感图形最为常用的重要技术之一，它能有效模拟和增强景物表面的细节特征，而不需要增加几何模型的复杂度，在三维游戏动画、虚拟现实、计算机辅助设计等领域有着广阔的应用前景。本文对生成曲面纹理的主要技术进行深入研究，内容包括纹理映射、实体纹理生成以及基于样图的曲面纹理合成。论文的主要贡献及创新之处如下： 1．对球面纹理映射算法进行深入研究，提出一种改进的半球面纹理映射算法。该算法以Bier与Sloan关于衡量球面纹理变形的准则为依据，引入面积等比约束，可使映射纹理的变形大为降低。并进一步将该算法的应用从半球面扩展到球面上任意区域的纹理映射。 2．对纹理映射方法进行深入研究，改进了传统方法中的S映射，有效降低了纹理变形；运用插值运算消除纹理接缝，取得了视觉上的纹理连续效果；并针对环形物体表面的纹理绘制问题，提出一种基于圆环中介面的两步纹理映射新算法。 3．提出一种基于样图的体纹理绘制新方法。该方法以木材体纹理为例，通过建立样图空间、体纹理空间和物体表面之间的几何映射关系，直接在物体表面绘制三维实体木纹，可较好地表现出木材样图中的纹理细节与纹理特征，有效提高计算机绘制实体木纹的真实感与多样性。 4．针对曲面纹理合成的若干关键问题进行了研究与改进。提出一种面向纹理合成的网格优化算法，以提高纹理合成质量；提出一种基于高度排序的三角形纹理块装配算法，以提高纹理地图集的空间利用率。还提出一种运用局部区域映射加速纹理合成的算法，大幅度提升曲面纹理合成速度。 5．设计并实现一个能够集成多种三维表面纹理生成算法的实验系统。针对纹理图像的预处理问题，提出的两个改进算法：(1)提出一种保持图像亮度的局部直方图均衡算法用于纹理图像对比度增强；(2)构造了一种基于C~2连续Catmull-Rom样条函数用于纹理图像的实时缩放处理。更多还原

【Abstract】 Surface texturing technique is one of the most popular techniques of realistic graph rendering. It can efficiently simulate the details of 3D surfaces without increasing the complexity of the geometric model, and has been widely applied in many fields such as 3D game, computer animation, virtual reality, CAD and so forth. In this thesis, we deeply studied some texture techniques, such as texture mapping, solid texture rendering and texture synthesis from samples etc. The main contributions and innovations are as follows:1. The method of two-step texture mapping is discussed and an improvement is made on the S mapping of it, which can effectively reduce the distortion of mapped texture. By using the weighted interpolation, the junctures of mapped texture patches can be removed and the visual quality of produced texture can be amended. Then a new algorithm of two-step texture mapping for annular objects is presented using a torus as the intermediate surface.2. The techniques of sphere texture mapping is studied and an improved algorithm of hemisphere texture mapping is proposed, which can obviously decrease the distortion of mapped texture by obeying the non-distortion criterions of sphere texture mapping and introducing a constraint of equal area-ratio. Moreover, we extended the algorithm to solve the problem of texture mapping for partial area of a sphere.3. A novel algorithm of rendering solid texture from samples is proposed, which can render solid texture directly onto an object surface by establishing geometrical mappings among the specimen space, solid texture space and object surface. The solid texture produced by the method can represents texture details on the samples and is continuous on the conterminous surfaces of an object. Therefore, the reality and diversity of texturing is evidently raised.4. A novel algorithm is proposed to speed up the process of surface texture synthesis, which uses local area texture mapping. A mesh-optimizing algorithm is presented which is used in the mesh preprocess of surface texture synthesis. Moreover, a texture triangular assembly algorithm for setting texture atlas is presented which is based on triangular height sorting to raise the space usage rate of the atlas.5. An experiment system is designed and implemented, which can adopt many texture rendering methods. In the system, two novel algorithms are proposed for texture preprocessing: one is the local histogram equalization algorithm with image brightness preservation, which is used to enhance the contrast of the texture; another is the Catmull-Rom spline method with更多还原