基于细分曲面控制网格优化的光滑树模型重建  

Smooth tree surface reconstruction based-on optimization of initial control mesh of subdivision surface

作　　者：黄正宇 张志毅[1] 耿楠[1] 胡少军[1] HUANG Zheng-y u;ZHANG Zhi-y i;GENG Nan;HU Shao-jun(College of Information E ngineering,Northwest A&F University,Yangling,Shaanxi,C hina,712100)

机构地区：[1]西北农林科技大学信息工程学院

出　　处：《计算机仿真》2019年第12期174-179,227,共7页Computer Simulation

基　　金：国家自然科学基金项目(61303124);中央高校基本科研业务费重点项目(2452017343)

摘　　要：树木的三维模型在虚拟现实、景观设计及农林业应用方面有重要的价值。但由于树木结构复杂,其枝干以及分杈的真实感重建仍是一个很有挑战性的问题。为构造光滑的树枝分杈,生成连续且完整的树模型,本文提出一种基于细分曲面初始控制网格优化生成树枝光滑曲面的新方法。利用树的骨架信息,首先以各个骨架结点为原点建立局部坐标系,利用枝条间的夹角调整各基本单元初始旋转方向,构建类长方体状的四边形网格作为基本树枝或树杈单元,采用自下而上的优化算法,调整相邻树杈单元间连接顶点位置,形成具有流形结构的初始控制网格。最后,应用Catmull-Clark细分算法,生成完整的树木模型。实验结果表明,该方法可有效重建具有连续分杈结构的真实树模型。Modeling realistic branches and ramifications of trees is a challenging problem for their complex geometric structures.To model a complete and continual tree quadrilateral mesh with smooth ramifications,we propose an optimization method to calculate an initial control mesh for Catmull-Clark subdivision surface.Using a tree skeleton and thickness as input,we firstly built a local coordinate for each skeleton node,and oriented each node properly according to the angle between parent branch and its child branch.Then we created corresponding basic branch unit and ramification unit with cuboid-like quad-mesh reasonably.To obtain a manifold initial control mesh for connection,a bottom-up optimization algorithm was applied to adjust the positions of vertices for each basic ramification unit.Finally,Catmull-Clark subdivision was used to generate tree model with smooth ramifications.The result shows that our method can generate realistic tree quad-mesh effectively.

关 键 词：细分曲面 树木建模 四边形网格 优化 

分 类 号：TP391.9[自动化与计算机技术—计算机应用技术]