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1、第29卷第7期计算机应用Vo.l29No.72009年7月JournalofComputerApplicationsJuly2009文章编号:1001-9081(2009)07-1901-05由点云数据重建的隐式曲面的可视化算法122杨军,诸昌钤,邢琪(1.兰州交通大学机电工程学院,兰州730070;2.西南交通大学信息科学与技术学院,成都610031)(yang@jmai.llzjtu.cn)摘要:针对由点云数据重建的隐式曲面提出一种新的基于粒子系统的可视化算法。首先,基于平行线束的初始化方法在隐式模型表面找到均匀分布的采样点,避免原来粒子系统中的
2、分割-死亡过程;用共轭梯度法替代原来粒子系统中的梯度下降法作为优化算法,将每一个椭圆粒子累进移动到低能量状态,避免了较长的收敛时间和围绕最小值的摆动现象;用贪婪选择法选择能够覆盖整个曲面的且不产生空洞的活动子集;松弛过程进一步改善依赖曲率的各向异性粒子采样。本文的粒子专门为基于Splats的表示法而设计,可以直接转换为椭圆Splats而不需要任何改动。因此,本算法可以快速、高质量地绘制出复杂隐式曲面模型。关键词:粒子采样;曲面splatting绘制;隐式曲面;点元;各向异性中图分类号:TP391文献标志码:AAlgorithmforvisualization
3、ofimplicitsurfacesreconstructedfrompointclouddata122YANGJun,ZHUChangqian,XINGQi(1.SchoolofMechanicalandElectricalEngineering,LanzhouJiaotongUniversity,LanzhouGansu730070,China;2.SchoolofInformationScienceandTechnology,SouthwestJiaotongUniversity,ChengduSichuan610031,China)Abstract:I
4、nthispaper,anovelrenderingalgorithmforimplicitsurfaceswhicharereconstructedfrompointclouddatabyusingaparticlesystemwaspresented.First,analternativeinitialtechniquebasedonbundlesofparallellineswasusedtofindinitialpointsthatwereevenlydistributedonthesurface.Becauseofitscharacteristics,
5、theusualsplitanddeathcriterionofparticlesystemwasnotneeded.Second,eachellipticalparticlewasmovedtowardsaprogressivelylowerenergystateusingaconjugategradientmethod,whichreplacedthegradientdescentasanoptimizationmethodtoavoidverylongconvergencetimeandirreconcilableoscillationaroundt
6、heminimum.Third,agreedyselectionstrategywasusedtochooseasubsetofactiveparticleswhichguaranteeaholefreeapproximation.Finally,arelaxationprocessfurtherimprovesthecurvaturedrivenanisotropicparticlesampling.Theproposedellipticalparticleswerespeciallydesignedforsplatbasedrepresentationa
7、ndcouldbedirectlyconvertedintoellipticalsurfaceSplatswithoutanymodification,thushighperformancerenderingofcompleximplicitsurfacescanbeobtained.Keywords:particlesampling;surfacesplattingrendering;implicitsurface;pointelement;anisotropic化方法,曲率控制的各向异性粒子采样算法和一个松弛优化0引言过程,在隐式曲面模型表面产生成千上万
8、个粒子。其次,直接点元可
