| 摘要: |
| 为在保留植物器官形态重要特征的前提下，适度精简原始三角网格数据，以满足计算机三维建模及应用的需要。通过改进Isler等“基于三角形折叠的网格简化方法”，提出了能够有效解决简化过程中出现网格交叉、大钝角三角形和狭长三角形现象的算法，构建精简叶曲面网格的新方法，并使用三维激光扫描仪采集得到的烟草叶片结构数据对该方法进行评价。结果显示当冠层简化比例为90.3%时，渲染效率提高86.1%，并且简化后叶片仍然逼近原始结构。结果表明：使用该算法不但能显著减少叶曲面三角形网格的数目，而且能很好地保留叶曲面形态特征。该算法可应用于不同形态类型叶片的简化，包括褶皱度很大的叶片。该研究可为植物冠层可视化与植物冠层光环境模拟等方面提供有力的支持。 |
| 关键词: 叶片曲面 网格简化 三角形折叠 三维模型 可视化 虚拟植物 |
| DOI：10.11841/j.issn.1007-4333.2014.04.28 |
| 投稿时间：2014-01-06 |
| 基金项目:中国烟草总公司（110201102008）；中国烟草总公司云南省公司项目（2011YN08） |
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| A study on simplification methods of leaf geometry mesh based on triangle-collapse algorithm |
|
XIAO Cui-xia1, LAO Cai-lian1, XU Zhao-li2, DUAN Tao3, YANG Yu-hong2
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| (1.College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China;2.Yunnan Academy of Tobacco Agricultural Sciences, Kunming 650021, China;3.College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China) |
| Abstract: |
| The triangular mesh method has been one of the common ways to accurately describe plant organ geometry.By using 3D laser scanning technology,3D data of plant organs (e.g.leaves) can be acquired with high precision.In the procedures of rendering a 3D scene or simulation of spatial light distribution in a canopy,however,tremendous computer disk space and a huge amount of calculation time could be cost if we directly use the original mesh data collected by using 3D laser scanning.This study aims to find a solution which can be used to properly simplify the original data of triangular mesh so as to minimize the time consumption of computer calculation,and preserve the principle characteristics of canopy architecture.By improving the mesh simplification algorithm proposed by Isler and others which is based on triangle collapse,it proposed an algorithm to solve mesh cross-over problem that often occurs in the process of mesh simplification,and reduce the probability of long-narrow triangles,concave polygons and other irregular triangles in the triangular mesh,so as to enhance the solid rendering effects.For evaluation of the proposed method,it was used to simplify triangular mesh of tobacco leaf blades attained by 3D laser scanning.It showed that when the canopy was simplified by 90.3%,rendering efficiency increased by 86.1%,and the simplified leaf geometry is still close to the original.It indicates that the mesh number of leaf blades can be reduced significantly while their geometry still closes to the originals.This algorithm can be applied to different kinds of complex geometrical shapes,e.g.large and undulated leaves.The study provides a reliable solution for the requirement of simplifying complex geometrical shapes in computer landscape visualization,simulation of spatial light distribution of crop and forest canopies,and other applications. |
| Key words: blade surface mesh simplification triangle collapse three-dimensional model visualization virtual plant |
