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    基于线元几何的旋转面点云数据旋转轴提取算法

    An Estimation Algorithm of the Axis of Rotation from 3D Cloud Data Based on Line Element

    • 摘要: 当前逆向工程CAD建模技术中,由于基于特征的曲面重构技术在精确表达原始模型、还原设计意图以及快速建模中所具备的优势,使其逐渐成为逆向工程领域新的研究热点.为实现海量数据快速特征提取,提出了一种基于线元几何、线性丛的旋转面点云数据旋转轴提取算法.算法首先将三维空间中的点投影到线元空间中,构建线性丛,而后在线性丛上拟合运动方程,通过特征参数计算旋转轴位置.此方法无须精确估算曲面法矢,有效地提高了特征提取速度.在算法中设计并使用了K-Local-RANSAC算法进行快速离散区域扩张并排除外点,保证了算法的健壮性.实验证明,本算法对于包括圆环面在内的旋转面都能得到较好的效果,而且能较好地适用于碎片数据及含有噪声的情况.

       

      Abstract: Because of the advantages on accuracy and expeditiousness in recent CAD modeling and reverse engineering, feature-based surface reconstruction becomes a hot topic in reverse engineering. Especially, 3D shape recognition and feature extraction is the difficulty and key point of the feature-based reverse engineering. To improve the performance and robustness, a new method for the estimation of the axis of rotation based on line element geometry, line complex and kinematic equation is presented. The method first projects the data points of a 3D volume to a line element image-space. A linear complex of the line elements is built and then the axis is approximated by fitting a kinematic equation on it. It is more efficient and faster than the previous methods because it doesnt need to estimate accurate surface normal vector of the cloud data. A new discrete region growing technique, called K-Local-RANSAC, is adopted to exclude the influence of the outer points and ensure the robustness. Line element geometry is employed to effectively perform the presentation of complex objects according to surface type. The K-Local-RANSAC algorithm uses linear complex to perform the classification. The discrete region growing mode improves the efficiency obviously. However, the effectivity on general rotational surface including torus and noise and fragment cloud points has been proved by experiments.

       

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