医学数据可视化及软组织建模

医学数据可视化及软组织建模第1页共63页┊┊┊┊┊┊┊┊┊┊┊┊┊装┊┊┊┊┊订┊┊┊┊┊线┊┊┊┊┊┊┊┊┊┊┊┊┊医学数据可视化及软组织建模软件工程黄鹏飞指导教师顾力栩【摘要】自百年前伦琴发现X射线以来，医学图像可视化经历了革命性的发展。医学知识、物理概念、数学方法和计算机科学理论有机地融合在医学图像处理之中。医学虚拟现实是计算机科学家孜孜不倦的追求。近年来，人体器官软组织的三维建模更是计算机图形学的重要研究课题。而软组织建模是实时手术虚拟和人机交互的基础。本文提出并讨论了质点弹簧算法，它将形变物体表面建模成质点弹簧网络，其计算量小，但是算法精度不高。然后介绍了中心线描绘算法，这种新型算法通过中心线信息对表面进行重绘，从而模拟形变，常被用作图像的分割、配准。虽然它的实时性不是很理想，但是它重绘的思路在软组织建模中颇有价值。于是，笔者结合了简化了的中心线描绘模型与质点弹簧模型，即在物体主要受力形变区域采取质点弹簧模型，在其它区域采取中心线描绘模型。这样既保证了局部形变的实时性，同时也保证了全局形变的逼真性。由于医学数据可视化是软组织三维建模的前提，本文还将介绍可视化相关的三维重建、图像分割算法等问题。除了核心的三维建模部分，本文亦将介绍人机交互技术、力反馈、碰撞检测、实时性与精确性等手术虚拟相关问题。【关键词】医学图像网格形变质点弹簧中心线描绘【Abstract】Since100yearsago,whenRoentgendiscoveredx-rays,medicalimagevisualizationhasrevolutionarilydeveloped.Medicineknowledge,physicsconcept,mathematicsmethodandcomputersciencehaveinterdisciplinarilyworkedtogetheronthemedicalimageprocessing.Itisinherentforthecomputerscientiststosimulatethemedicalreality.Inrecentyears,the3Dmodelingofhumanorganicsofttissuehasbeenanimportantresearchsubjectincomputergraphics.Andthesofttissuemodelingisthebasisforthereal-timesurgerysimulationandhumancomputerinteraction.Inthispaper,weproposeanddiscussthemass-springalgorithm.Itmodelsthesurfaceofdeformableobjectasthenetworkofmassesandsprings.Itscomputationalcomplexityislowbutitislimitedinaccuracy.Andweproposealatestalgorithm,medialrepresentation.Itredrawsthesurfacebasedonthecenterlineinformationtomodelthedeformationanditisoftenusedforimagesegemantationandregistration.Althoughitsreal-timepropertyisnotidealenough,wecantakeadvantageofitsredrawingstrategyinsofttissuemodeling.Therefore,wecombinethemass-springandmedialrepresentationmodelssothatwecanachievethereal-timeperformanceoflocaldeformationand,atthesametime,theaccuracyofentiredeformation.Becausemedicaldatavisualizationisthepreconditionforsofttissuemodeling,weintroducetherelatingcontentsof3Dreconstructionandimagesegmentation.Besides3Dmodeling,whichisthecorepartofsurgerysimulation,wealsointroducethesimulation’srelatingissuesincludinghumancomputerineractiontechnique,forcefeeback,collisiondetection,accuracyandreal-timeperformance.【Keywords】MedicalImageMeshDeformationMass-SpringMedialRepresentation医学数据可视化及软组织建模第2页共63页┊┊┊┊┊┊┊┊┊┊┊┊┊装┊┊┊┊┊订┊┊┊┊┊线┊┊┊┊┊┊┊┊┊┊┊┊┊目录医学数据可视化及软组织建模11引言31.1研究背景·····························································································31.2研究目标·····························································································31.3内容组织·····························································································32医学数据可视化技术32.1概述·····································································································32.2医学数据三维重建··············································································32.2.1医学图像数据格式·······························································32.2.2表面绘制技术·······································································32.2.3体绘制技术···········································································32.3医学图像分割······················································································32.3.1形态学方法···········································································32.3.2快速步进法···········································································32.4医学可视化平台开发实现··································································32.4.1VTK软件开发包····································································32.4.2ITK软件开发包····································································32.4.3Atamai手术导航软件开发包··············································32.4.4基于Atamai的医学可视化平台·········································33三维物体表面网格化技术33.1概述·····································································································33.2VTK数据格式····················································································33.3行进立方体算法··················································································33.4气球算法·····························································································34人体软组织三维建模34.1概述·····································································································34.2质点弹簧算法······················································································34.2.1质点弹簧拓扑结构·······························································34.2.2质点弹簧系统原理·······························································34.2.3表面模型···············································································34.2.4体模型···················································································3医学数据可视化及软组织建模第3页共63页┊┊┊┊┊┊┊┊┊┊┊┊┊装┊┊┊┊┊订┊┊┊┊┊线┊┊┊┊┊┊┊┊┊┊┊┊┊4.3中心线描绘算法··················································································34.3.1中心线几何结构···································································34.3.2根据中心线绘制表面···························································34.4质点弹簧算法与中心线描绘算法的结合··········································34.5三维建模应用程序开发实现·····················································