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点云模型的特征计算及其在真实树木重建中的应用
其他题名Feature Computation on Point Cloud and its Application in Real Tree Modeling
程章林
学位类型工学博士
导师胡包钢 ; 张晓鹏
2008-06-10
学位授予单位中国科学院研究生院
学位授予地点中国科学院自动化研究所
学位专业模式识别与智能系统
关键词点云模型 数字几何处理 微分几何量估计 圆柱拟合 真实树木重建 Point Cloud Digital Geometry Processing Estimating Differential Geometry Properties Cylinder Fitting Reconstruction Of Real Trees
摘要随着三维激光扫描技术的发展,现实世界中越来越多的复杂物体都可以通过激光扫描的方式建立其三维数字几何模型,并且这种基于实物测量的数字化建模方法正逐渐成为一种发展趋势。三维几何模型的大量出现和广泛应用推动了学术界在数字几何处理方面的研究。本文重点研究了点云模型特征计算中的两个基础性的课题:点云模型的底层局部几何特征估计和高层语义特征——圆柱面参数的快速计算,并以此为基础考虑了一个实际应用问题——真实树木的三维重建。 论文的主要贡献包括以下几点: 1.散乱点云曲面的二阶微分量估计:针对不规则的离散点云数据提出了一种基于法向拟合的微分几何量估计方法。该方法充分利用邻域内所有点的法向信息,根据单位法向量两分量及其偏导数来计算二阶微分量,方法的最大优点在于估计结果与局部坐标系的选择无关,并且在法向拟合完成后能够对法向进行修正,得到更准准的估计结果。 实验表明,该方法在不规则的散乱点云数据上能获得比较优异的估计性能。 2.快速圆柱拟合:通过引入一种新的近似几何距离度量,提出了一种快速圆柱拟合方法。该方法能使非线性圆柱拟合问题部分线性化,将非线性优化的参数个数从~5~降到~2~。这种转化一方面提高了曲面拟合的计算速度,另一方面也在一定程度上避免了非线性优化问题由于优化初始值选取不当而陷入局部最优的问题。 3.真实树木枝干三维重建:基于三维激光扫描仪单次测量数据,提出了一种真实树木的三维重建方法。该方法选取春冬季节不带树叶的落叶树作为对象,专注于树木枝干的重建,力求准确重建树木的分支结构及各分支的半径信息,算法充分利用单次扫描数据点规则分布的特点,主要处理步骤都在深度图像空间中进行,重建过程简单快捷,重建结果可以用于真实树木的测量。
其他摘要With the development of 3D range scanning, more and more complex objects are scanned to generate their 3D geometric models,and this type of measure-based modeling has become an important trend in computer graphics. The widespread requirements of 3D geometry models push the research on digital geometry processing. In this thesis we focused on two fundamental issues on the estimation of local geometry properties and the reconstruction of cylinder surface. Based on these researches, we developed an approach to reconstruct real trees from a single scan. The main contributions of this thesis are as follows: 1.Estimating differential geometry properties from unorganized point cloud. An accurate and robust method is proposed to estimate the curvatures and Darboux frames from unorganized point clouds. This method takes into account the normal information of all neighboring points and directly computes second-order differential quantities from the variation of unit normal vectors, which improves the accuracy and robustness of curvature estimation on irregular sampled noisy data. The main advantage of the approach is that the estimation of curvatures at a point does not rely on the accuracy of the normal vector at that point, and the normal vectors can be refined in the process of normal fitting. Compared with the state-of-the-art methods for estimating curvatures and Darboux frames on both synthetic models and real point clouds, the approach is shown to be more accurate and robust for noisy and unorganized point cloud data. 2.Fast cylinder fitting. A fast cylinder fitting method is presented by using a new approximate distance between a point and the cylinder surface. The method can transform the conventional cylinder fitting with 5 parameters to a nonlinear optimization with only 2 parameters, which not only reduces the time complexity of the nonlinear optimization in cylinder fitting but also alleviate the solution dependence on the initial estimation and avoid local optimization to some extent. 3.Simple Reconstruction of Tree Branches. We present a multi-process approach that is mainly performed in 2D space to faithfully construct a 3D model of the trunk and main brunches of a real tree. The approach takes a single scan of a bare tree using a laser scanner as the input source data for modeling, and focus on the reconstruction of the branching structures and dimensions of the tree.
其他标识符200418014628013
语种中文
文献类型学位论文
条目标识符http://ir.ia.ac.cn/handle/173211/6121
专题毕业生_博士学位论文
推荐引用方式
GB/T 7714
程章林. 点云模型的特征计算及其在真实树木重建中的应用[D]. 中国科学院自动化研究所. 中国科学院研究生院,2008.
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