计算机专业外文翻译

1、精选优质文档-倾情为你奉上沈 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 ge

2、neration using 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 cur

3、rently represents 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 mathemati

4、cal tools can 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 (M

5、S Internet Explorer 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 applica

6、tions of 3D modeling 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: Adoptin

7、g openGL, VRML，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

8、 do in the aspects 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

9、a personnel to 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

10、 the meantime, 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

11、 virtual realistic 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,

12、there being still 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 measu

13、red at every 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 fa

14、ster and clearer. 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 obtai

15、ned from the 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 layo

16、ut in the Czech 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

17、 these problems 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 tria

18、ngulation method 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

19、 of these results.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

20、 resulting model 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

21、to respect the 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 e

22、nvironment it 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 Toolbo

23、x provided that 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 pro

24、perties de_ned 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

25、 each point must 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_c

26、ation of VRML 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 Con

27、tact v. 4.4. 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 vir

28、tual model provides 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 dri

29、ven from the 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

30、 mention the 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 a

31、nimation is very 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

32、器和网景的领航员浏览器）已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

33、的进程方面显得力不从心，与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

34、共和国的自动监控系统（AIM）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