【作者】 卢波；

【导师】 葛宝臻；

【作者基本信息】 天津大学 ， 光学工程， 2006， 硕士

【摘要】 随着计算机技术以及三维成像的软硬件技术的迅猛发展,三维数字化技术愈来愈多地得到人们的关注和应用。三维数字化技术概括地说可以分为数据采集、表面网格重建和表面信息获取三个过程。表面网格重建是从采样于三维物体表面的海量点云数据出发,生成具有正确拓扑关系的物体网格表示,是连接点云数据和物体表面模型的桥梁。三维表面网格重建效果的好坏直接关系到人们对物体的认知、特征提取和三维测量等后续应用。另一方面,三维表面重建过程一般是在只知道点云数据而不知道物体拓扑关系的情况下进行的,涉及到计算几何、拓扑学,以及计算机图形学等多领域的知识。因此三维表面重建算法的研究具有重大的理论意义和现实意义。论文主要以本实验室激光三维扫描仪得到的点云数据为研究对象进行研究。主要工作包括以下几部分:1、数据预处理。研究了求最大连通域方法删除噪声的算法,基于相邻点连线角度判定方法的数据简化算法。给出了这些算法对数据的处理结果,并进行了分析。2、三维表面重建。在对步进立方体网格重建算法进行分析的基础上,提出了改进算法。利用基于局部切平面簇的方法对数据点云进行切平面的估算、法向量的调整和计算有向距离函数,提高了重建速度,改善了重建效果。3、在网格简化的基础上采用局部优化算法对三维网格实施优化,在保证网格显示质量的前提下,减少了网格数目,提高了显示速度。4、采用VC++和OpenGL混合编程技术编制了用于数据预处理和三维表面重建及显示的应用软件,开发出了友好且实用的用户图形接口界面。并对不同的三维点云数据进行了重建实验,取得了较好的结果。更多还原

【Abstract】 With the rapid development of the software and the hardware which have a close relationship with 3D imaging, 3D digitizing technology is paid more attention widely. Generally, there are three main parts in 3D digitization technology: sampling, surface-mesh reconstruction and surface information obtaining. Surface-mesh reconstruction is the process of constructing object-mesh with correctly topological structure on vast 3D point cloud data. It is the bridge to connect point cloud data and object surface. The quality of the reconstruction plays an indispensable role in the subsequent progresses, such as object recognition, character extraction and 3D measurement. On the other hand, 3D surface is only reconstructed on point cloud date, the topological structure of the object isn’t known beforehand, much knowledge in many areas are used such as computational geometry, topology and computer graphics. Thus the research of reconstruction algorithm on 3D surface is essential in theory and practice.The article researches on point cloud date sampled by the laser 3D scanner, which was designed by our laboratory. There are four parts as follows.1. Pretreatment on point cloud data. Two algorithms are used: the algorithm to delete noises by the method of maximum connected domain and the algorithm to simplify point cloud data by estimating degree between lines of adjacent points. And results of these algorithms are analyzed.2. 3D surface reconstruction. This is the main part of the article. An improved algorithm is applied which based on the marching cubes mesh reconstruction algorithm. By the aid of local-tangent-planes-based method, the tangent plane is estimated, the normal vector is adjusted and the directional distance function is calculated. Both the speed and the effect of the reconstruction are improved.3. Optimizing of 3D meshes. After mesh simplification, the 3D meshes are optimized by local optimization arithmetic. Results show that the meshes are reduced and the speed of display is improved. Meanwhile, the quality of mesh-displaying is not deteriorated any more.更多还原