计算机专业外文翻译.doc

《计算机专业外文翻译.doc》由会员分享，可在线阅读，更多相关《计算机专业外文翻译.doc（12页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、沈 阳 工 业 大 学软件学院外 文 翻 译专 业： 计算机科学与技术 学生姓名： 学 号： 指导教师： VIRTUAL REALITY MODEL OF AIR POLLUTIONM. Mudrova, A. Prochazka, and M. KolnovaInstitute of Chemical Technology, Department of Computing and Control EngineeringAbstractThe paper is devoted to the description of virtual reality model generation usin

2、g the system Matlab and its Virtual Reality Toolbox. The selected possibilities of interconnection of both systems (Matlab and VRML) are demonstrated by means of visualisation of two-dimensional interpolation of air pollution data.1 IntroductionPresentation of three-dimensional data currently repres

3、ents a very topical theme in many areas, and not only technical ones. Clear and intelligible arrangements of information in the 3D model is necessary for example in medicine and it is used more and more frequently in other areas. Results of information processing using complex mathematical tools can

4、 naturally lead to formulation of a three-dimensional graphical model. It has been possible to observe or process spatial data for all users of personal computers since the VRML (Virtual Reality Modeling Language) had been developed 5, 6, 7. The most frequently used Internet browsers (MS Internet Ex

5、plorer and Netscape Navigator) have a VRML viewer built in. There are also many other freeware plug-in modules available on the Internet with which one can enter the virtual world and observe it and possibly control it as well. Thanks to these facts, it is expected that areas of applications of 3D m

6、odeling will grow.The goal of this paper is to describe the process of formulation of a 3D model of air pollution level in the Czech Republic using the system Matlab, and its export to VRML.2 BackgroundThe virtual realistic scene establishes to generally have two kinds of paths: Adopting openGL, VRM

7、L，Direct 3D is the 1st。For non-calculator professional personnel to say, make use of OpenGL to write a complicated 3D application doubtless is a challenge. VRML language oneself writing is very easy, but this kind of language function be weaker, and it seems to be to lack the ability to do in the as

8、pects of handle complicatedly progress, with other high classic language of the conjunction be also not enough convenience. Direct 3Ds are a 3D sketch plait distance API that the Microsoft companies release, it mainly applied at the plait distance of 3D game, needed to weave a distance a personnel t

9、o have higher ability of C+. High language of plait distance achievement bottom, as a result is also hard and universal. Therefore establish a virtual realistic scene to need to there is better plait distance through this kind of path ability, need to acquaint with a certain language in the meantime

10、, suitable for professional development personnel;The 2nd method is to adopt a certain and virtual realistic environment to establish tool to establish, this kind of tool provides a valid path which averts from process and language norm of the complications plait distance to establish a virtual real

11、istic scene for the customer according to a certain language and the development terrace, this tool has already have currently some experiment system is report?And the majority be according to the VRML. But regardless according to which terrace, see still not mature from the technique, there being s

12、till more problems should be resolved.3 Real Data DescriptionAutomation Imission Monitoring System (AIM) in the Czech Republic that includes more than 100 measuring stations 3 provides regular measurements of chosen components in the air. Con-centrations of selected pollutants are measured at every

13、station in 30 minute intervals during the whole year. These data allow to watch the air pollution level at exactly located points, and by using interpolation methods, in the whole area of the Czech Republic, as well. Graphically presented results of interpolation make the imagination faster and clea

14、rer. They could be also compared with parallelly performed NOAA (The National Oceanic and Atmospheric Adminis-tration) satellite observations and namely concentrations of dust particles in the air. The one years time series representing current concentrations of the PM10 pollution obtained from the

15、AIM stations has been kindly provided by the Czech Hydrometeorological Institute in Prague. The data observed at locations presented in Fig. 1 were preprocessed by means of compensation for values of measurement failures and elimination of distant values 4.Figure 1: The AIM station layout in the Cze

16、ch Republic with marked Delaunay triangulation4 Two Dimensional Interpolation MethodsIt is possible to use various interpolation methods for estimation of values of an observed pollutant in other non-measured points specied by a selected orthogonal net. The description and comparison of these proble

17、ms has been presented in 4. It is possible to use the simplest method of the 0-th order - the nearest neighbour method that interpolates the surroundings of a given station by the same value measured in the station. Voronoi diagrams 1 limit the surrounding borders. Related Delaunay triangulation met

18、hod presented in Fig. 1 is used for higher-order interpolation (bilinear, cubic, spline). A selected method applied to the array of calculated concentrations values results in the orthogonal net de_ning longitude and latitude.The three-dimensional model represents a natural presentation of these res

19、ults.5 Three Dimensional Model in Matlab and VRML EnvironmentThe spline interpolation method has been applied for the data PM10 (particular material up to 10 _m) measured in the AIM system of the Czech Republic at a selected time. The algorithm realized in the Matlab R12 system provides resulting mo

20、del of air pollution presented in Fig. 2. Figure 2: Result of spline interpolation of PM10 concentration realized in the Matlab system.Virtual Reality Toolbox v.2 2 has been then used for creation of the VRML _le (.wrl). Using any text editor for modi_cation of this _le it is necessary to respect th

21、e following require-ments for the VRML _le creation:1. Coordinate systems: Both the Matlab system and the VRML use the right-handed Cartesian coordinate system, but rotated around the x-axis as given in Fig. 3Figure 3: Coordinate systems in Matlab and VRML2. Units: While in the Matlab environment it

22、 is possible to use any unit system, VRML expects that the length values are given in meters, angles in radians and time in seconds3. Nodes marking: It is possible to communicate with the selected set of the VRML nodes in existing virtual world from Matlab and its Virtual Reality Toolbox provided th

23、at the nodes in VRML are named using the DEF keyword.Having in mind these rules it is possible to export a 3D model created in the Matlab environment enabling visualization by mesh or surf commands to VRML environment in a very simple way using vrml(handle; filename) command. Object properties de_ne

24、d in Matlab and given by the corresponding constant handle are translated into the VRML node parameters in this way.As an example it is possible to assume the point coordinates as parameters of the node coordinate de_ned as a part of the transformation hierarchy. In the VRML environment each point m

25、ust be declared by all its coordinates - x, y, z, respectively - on contrary with Matlab allowing to draw the model with missing z-coordinates as well. Further model properties are set using other nodes (viewpoint; transform,.). Allocation of names to nodes allowing the following modi_cation of VRML

26、 nodes parameters from Matlab environment must be defined in the .wrl _le.Figure 4: VRML model of the air pollution level in the selected regionThe VRML model of air pollution presented in Fig. 4 has been veri_ed in Netscape Nav-igator v. 4.77 with recommended plug-in module Blaxxun Contact v. 4.4.

27、Using this software tools it is possible_ to observe VRML model_ to go through prede_ned points of view_ to change the way of movement in the modelOther possibilities include the virtual world control through the Virtual Reality Toolbox com- mands speci_ed in 2.6 ConclusionPresented virtual model pr

28、ovides the possibility to view the air pollution situation in the Czech Republic. It is further easy to insert this model to Web pages. Although the VRML does not enable to solve mathematical problems by itself it can be used very eciently to create animated three dimensional scenes driven from the

29、Matlab and Simulink environment allowing signal or system modelling in the standard way.The paper summarises the initial authors experiences with Virtual Reality Toolbox only. It is assumed that the presented model will be further developed in the future. As an example it is possible to mention the

30、introduction of dynamical nodes to watch the time development of air pollution. Proposed applications include three-dimensional models of air pollution and biomedical models based upon three-dimensional magnetic resonance observations as well. In both these cases the visualization and animation is v

31、ery useful.空气污染的虚拟现实模型本文致力于通过Matlab系统的虚拟现实语言及其工具箱来描述并建模。选用这个系统（Matlab系统和虚拟现实建模语言系统）可以通过可视化的二维插补法来显示出空气污染的数据。1 引言近年来，三维数据信息在很多领域上（不仅仅在科技方面）被关注，它提供清晰且智能的信息编排在3D模型中是非常必要的，例如医疗方面。而且它在不同领域上的使用也是越来越频繁。使用复杂的数学工具处理信息的结果是随之自然形成的三维图像模型。从虚拟建模语言被开发出来后，便可以观察或处理个人计算机上所有用户的三维空间的数据。目前最常用的互联网浏览器（微软的IE浏览器和网景的领航员浏览器）已

32、经内置了浏览虚拟现实建模语言的插件。这里还有许多其它的免费的插入式模块的软件用于互联网，那些软件能够进入虚拟世界并观察它、甚至是很好的控制它。多亏这些事实，3D建模的应用领域按着预期发展。 这篇论文的目标是使用Matlab系统来对捷克共和国空气污染等级的三维模型进行处理，并且使用虚拟现实建模语言作为最终的表现形式。2 背景虚拟现实场景的创建一般有两种途径：第1种是采用openGL，VRML，Direct3D等语言创建，对于非计算机专业的人员来说，利用OpenGL编写出复杂的三维应用无疑是一个挑战。VRML语言虽然本身编写起来非常简单，但这种语言功能较弱，而且在处理复杂的进程方面显得力不从心，与

33、其它高级语言的连接也不够方便。Direct3D是微软公司推出的三维图形编程API，它主要应用于三维游戏的编程，需要编程人员具有较高的C+等高级语言的编程功底，因而也难以普及。因此，通过这种途径创建虚拟现实场景需要有较好的编程能力，同时需要熟悉某种语言，适合于专业的开发人员；第2种方法是采用某种虚拟现实环境创建工具来创建，这种工具基于某种语言和开发平台，为用户提供一个避开复杂编程过程和语言规范来创建虚拟现实场景的有效途径，这类工具目前已有一些试验系统被报告“而且大多数是基于VRML的。但无论基于哪种平台，从技术上看都还不成熟，尚有较多问题需要解决。3 现实数据的描述捷克共和国的自动监控系统（AI

34、M）的大概100多个测量站会定期提供被选中的大气的组成成分的测量数据，检验检测污染物质的浓度，每个站点每隔30分钟检测一次，持续一年。通过这些数据，使用插值方法查看捷克共和国的全境的数据，就可以在某个准确的地点看到当地空气污染的等级。通过图表展现出插值的结果会比想象出来的更快且更清晰。他们也可被用来与NOAA的卫星观测和粉尘在空气中的浓度平行进行对比。在这一年时间中的一系列代表着从观测站取得的污染物的浓度的结果由在布拉格的捷克水文研究所提供。图1地点的数据是通过对淘汰了的测量值进行补偿而得的。4 二维插值方法使用各种插值法都可以计算出正交网上没有被测量的点的污染。对这些问题的描述和对比已经在图

35、4中表现出来了。它可以使用最简单的第0序列-最邻近的方式是插入并找到有相同值的附近的站点。Voronoi图【1】限制了范围边界。图1里关于Delaunay三角形方法被用在高阶插值中（双线性，立方体，线条）。一个被选的方式应用在正交网上经度和纬度上列出的计算的浓度值的结果。而三维模型代表着这些结果的一个自然演示。5 在Matlab系统和虚拟现实建模语言环境下的三维模型样条插值法已经应用到数据为PM10（特殊材料到10um）的测量，在一个特定的时间里的捷克共和国的自动监控系统。该算法意味着在Matlab R12系统提供的空气污染的模型结果在图2中被展示。虚拟现实工具箱已经用来建立VRML (.wr

36、l)文件了。用任何文本编辑器编辑这个VRML (.wrl) 的程序都必须谨慎的按照下面的要求来创建VRML文件。1. 坐标系统：无论是Matlab系统还是虚拟建模语言都是用右侧的直角坐标系，但是是按照像图3一样的按X轴旋转。2.单位：虽然在Matlab环境下有可能用任何的系统单位，但虚拟现实建模语言的长度值一般用米，角度一般用弧度，而时间一般用秒。3.节点表识：只要使用DEF关键字的节点便可连通那些来自Matlab和它的虚拟工具箱里的一组VRML节点与虚拟世界。记下这些规则便可以导出一个在Matlab环境中被创建的3D模型，并用简单的VRML命令(操作,文件名)使网孔或表面命令VRML环境启动

37、视图。在Matlab系统中被定义的，用相对不变的手法得出的物体属性也是这样被译成VRML节点参数。作为例子，它可能假设坐标点作为节点的坐标参数层次转换的一部分。在VRML环境中每一个节点必须分别在其坐标轴X,Y,Z中被提出。相反的基于Matlab允许在没有Z轴的情况下绘制模型。用其它节点可以组成更多模型）。给节点命名允许之后的VRML节点参数的修正，Matlab 环境下VRML程序节点参数必须在.wrl文件中被定义。核实。这使得使用这个软件工具成为可能。观察虚拟现实建模语言模型经过之前便被定义的观测点在模型中改变移动方式其他的可能包括通过虚拟现实工具箱控制虚拟的世界。6 总结被展示出来的虚拟模型给我们提供一个观察捷克共和国空气污染情况的可能。我们可以非常容易的把这个模型放到网页里。尽管虚拟现实建模语言不能够靠它本身解决数学问题，但它能够非常高效率的用来通过Matlab系统和Simulink环境去接收信息或创建一个栩栩如生的三维环境这篇论文概述了作者最初关于使用虚拟现实工具的经验，并推测将来这个模型将有进一步的发展空间。作为例子，可能提及的动态节点可以看到空气污染的时间发展变化。被提到的应用程序包括空气污染的三维模型和基于三维磁共振的生物医学模型。在这两种情况下，可视化与动画是很有用的。