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1.
交互式虚拟人脑内窥镜系统关键技术 总被引:1,自引:0,他引:1
目的为解决传统内窥镜方法的缺点。方法设计并开发了一套基于体绘制技术的交互式虚拟人脑内窥镜系统。结果给出了系统主要功能和流程,并且对系统实现中的3项关键技术:虚拟相机模型建立、漫游路径抽取和三维体数据的绘制方法作了详细介绍,改进的光线投射算法使得重建的三维模型图像清晰,绘制效率高。结论系统能够通过手动和自动两种方式进行器官内漫游并生成动画记录,为临床诊断和医学仿真提供了有效地支持。 相似文献
2.
《浙江科技学院学报》2017,(3)
针对三维动画制作中模型纹理绘制不够直观、效率低下等问题,提出一种实时交互式三维模型纹理映射算法,即通过交互式三维拾取准确找到三维模型与二维纹理图像对应点,直接在三维模型表面使用笔刷进行纹理图像的绘制。实验在Unity 3D引擎中进行,结果表明用户可以使用该算法进行纹理的交互式设计与合成,其笔刷定位精确,绘制过程帧率稳定,绘制得到的纹理图像质量较高。该方法对比传统制作流程中对三维模型展开UV,在二维图像处理软件中进行纹理绘制的方法更为直观、高效。 相似文献
3.
基于PC图形卡W-Buffer的交互直接体绘制 总被引:1,自引:0,他引:1
提出一种基于PC图形卡W Buffer的交互光线投射算法,这是一种面绘制与体绘制结合的快速体绘制方法.首先用3D分割等方法提取边界体素或用MarchingCubes等算法提取等值面,然后利用图形硬件预先投影这些边界体素或等值面以产生深度信息,最后由光线投射模块根据W Buffer中的深度信息快速找到实际等值面的位置,进行采样、着色、不透明度与颜色合成等渲染工作.这一方法不仅显著地加快了成像速度,而且不降低图像质量.实验结果表明,用该算法在PC机上以200×200分辨率渲染时,能达到10帧/秒的速度,基本满足虚拟内窥镜系统的动态导航和高质量图像要求,具有较大实用价值. 相似文献
4.
心脏超声虚拟内窥镜图像预处理技术 总被引:1,自引:0,他引:1
虚拟内窥镜是近年来兴起的一项崭新医学影像技术,将虚拟现实与科学计算可视化技术相结合,模拟传统的内窥检查过程而生成具有仿真效果的可视化图像.研发的三维心脏超声虚拟内窥镜系统(3DEIESS)可重建三维虚拟环境,使观察者"进入"被检查患者的心脏内部进行检查观察.采用基于同质掩模区域的滤波算法对超声图像斑点噪声进行抑制,应用brFCM算法对降噪后的超声图像进行初始分割,并使用多尺度分析与纹理对比度相结合的分割技术完成最终的图像分割.实验结果表明,在消除斑点噪声的同时,实现对超声图像边缘细节的有效保持,有助于提高三维心脏超声虚拟内窥镜显示效果. 相似文献
5.
基于有序体数据的最大密度投影算法 总被引:3,自引:0,他引:3
研究快速获取血管造影的方法,提出了一种基于有序体数据的新的最大密度投影算法.该算法采用Shear—warp投影思想,通过调整对有序体数据遍历的阈值实现快速绘制,在不影响显示有效信息的情况下,对中等规模的体数据能达到每秒10帧以上的绘制速度,并在微机上实现了血管造影图像的实时绘制. 相似文献
6.
探讨了CUDA下的虚拟内窥镜系统,成功的解决了传统虚拟内窥系统中存在的路径抽取耗时长,虚拟内窥效果失真,及交互不能实时显示虚拟图像等问题. 相似文献
7.
目的设计实现一个虚拟心脏系统原型,重点讨论其中的基于纹理映射的体绘制方法,给出用Java 3D软件方法实现纹理映射体绘制。方法获取CT心脏断层数据,对其进行预处理,在此基础上进行图像的滤波、分割、配准及裁剪,最后实现基于纹理映射体绘制的三维重构。结果用Java Java 3D实现了虚拟心脏系统原型中基于纹理映射的体绘制。结论采用软件方法(Java3D)实现了纹理映射硬件的功能,由于不需要三维纹理映射硬件的支持,降低了硬件成本。 相似文献
8.
针对汽车工业中虚拟油泥模型外观设计问题,采用一种六自由度输入设备并基于实时力反馈交互技术,提出一种新型的变刚度画笔模型以及触觉装饰方法,实现在虚拟三维物体表面实时触觉绘制与外观装饰.基于变刚度弹性理论,深入研究虚拟3D画笔的触觉行为.首先,采用一种弯曲弹簧振子模型来构建3D画笔的力学模型,并分析虚拟画笔实时变形与承受的绘制力之间的内在关系;接着,基于一种加权平均距离的碰撞算法,研究虚拟画笔与虚拟3D物体之间的碰撞检测问题;采用一种球扩展操作以获得弯曲画笔的最小包围球,进而计算得到虚拟投影平面;根据在一个采样点处的画笔变形,得到虚拟投影平面上的二维笔触;通过将二维画笔笔触实时地映射到三维对象表面,便可以得到三维笔触;沿着三维绘制方向,通过控制绘制力矩并叠加不同大小、形状的3D笔触便可得到3D笔道.仿真对比实验结果表明,所采用的画笔模型及方法可以有效增强用户虚拟绘制时的真实性. 相似文献
9.
结合图像处理技术和径向权混合方法,提出一种基于图像集的大规模虚拟地形自动生成算法.该算法首先由多幅图像色彩数据生成标准化地形拼接块模型,并通过滤波处理消除地形块内部的跳变现象;借助定义在地形块上的有限支撑径向权函数,对毗邻地形块的子块进行加权混合处理,实现了地形块的无缝拼接平滑过渡.该算法支持相关参数的交互式调整,使用户能够对地形的形状和平滑程度等进行有效控制.实验结果表明:该算法可以自动、快速、高效地生成满足不同形状和规模要求的虚拟地形模型. 相似文献
10.
虚拟内窥镜中心路径抽取技术 总被引:4,自引:1,他引:4
目的在空腔器官中提取一条最佳的用于虚拟内窥镜漫游的中心路径。方法采用基于距离变换的方法进行路径抽取。结果给出了虚拟内窥镜中心路径的定义,总结了中心路径的基本特性。结论在虚拟人脑内窥镜系统中实现了中心路径的提取,用于器官内窥检查,效果良好。 相似文献
11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness. 相似文献
12.
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly. 相似文献
13.
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well. 相似文献
14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation. 相似文献
15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。 相似文献
16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death. 相似文献
17.
Miao Maosheng 《华南师范大学学报(自然科学版)》2014,(6)
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula- 相似文献
18.
Yang Weitao 《华南师范大学学报(自然科学版)》2014,46(6):137-138
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re- 相似文献
19.
Bernard Kirtman 《华南师范大学学报(自然科学版)》2014,(6)
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that 相似文献
20.
《上海师范大学学报(自然科学版)》2014,(5):550
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with 相似文献