基于WebGIS的校园三维电子地图的设计与实现计算机毕业设计外文翻译.docx

1、基于WebGIS的校园三维电子地图的设计与实现计算机毕业设计外文翻译 The Design and Implementation of 3D Electronic Map of Campus Based on WEBGISI. INTRODUCTIONNowadays, digitalization and informatization are the theme of our times. With the development of information revolution and computer science, computer technology has penetrat

2、ed into all fields of science and caused many revolutionary changes in these subjects, the ancient cartography also cant escape. With the technical and cultural constantly progress, the form and the content of the map change and update as well. As the computer graphics, geographic information system

3、s (GIS) constantly applied to the Web, the conventional way of fabrication and demonstration has suffered great change, and the application of the Map has extended dramatically owing to the development of advanced information technology. Under these circumstances, cartography will be faced with prom

4、ising prospect. It has branched out into many new products. One of the products come into being is the e-map 1. With the rapid development of the computer technology, computer graphics theory, remote sensing technology, photogram metric technology and other related technology. Users require handling

5、 and analysis of three-dimension visualization, dynamic interactivity and show their various geo-related data, so much attention should be paid to the research of three dimensional maps. This article based on the Northeast Petroleum University and its surroundings designs and creates the three-dimen

6、sional electronic map. II. FUNCTIONDESIGNThree-dimensional electronic map system of campus based on WEBGIS has general characteristics of the common maps. Through pressing the arrow keys (Up, Down, Left, And Right) on the keyboard, one can make the map move towards the corresponding direction of tra

7、nslation. Through dragging mouse, one can see wherever he likes. Using the mouse wheel, you can control a maps magnitude, according to the users needs to view different levels of map. The lower left of the map where will display the current coordinate of the mouse on the map. In a div layer, we depi

8、ct a hotspot of new buildings, this layer can be displayed according to the different map layers, it also can automatically scale. By clicking on hot spots, it can show the hot spots specific information. One can also type into the query information based on his need, and get some relevant informati

9、on. In addition, one can choose to check the three dimensional maps and satellite maps through clicking the mouse. Major functions: User information management: Check the user name and password, set level certification depending on the permissions, allow users of different permissions to login the s

10、ystem via the Internet. The inquiry of Location information: System can provide users with fuzzy inquires and quick location. Map management: Implement loading maps, map inquires, layer management, and other common operations such as distance measurement, and maps zoom, eagle eye, labels, printing,

11、and more. Roam the map: Use the up and down keys to roam any area of the map, or drag-and-drop directly.III. THE PROCESS OF SYSTEM DEVELOPMENTTo the first, we collect the information which contains the outward appearance of architectural buildings, the shape of the trees the design of the roads. And

12、 then, we construct three dimensional scenes with 3DS MAX software 2. That is to say we render the scene and achieve the high-defmition map, after that we cut the map into small pictures with the cut figure program, at last we built the html pages which can asynchronous load maps and achieve the fun

13、ction of the electronic maps. The flow chart of the system development will be shown in Figure 1:Figure 1 system development flow chartTraditional maps have strict requirements on mathematical laws, map symbols and cartographic generalization when in design. The production of network landscape elect

14、ronic map also has its own technical standards which is superior to the traditional map. The three-dimensional electronic map has different zoom levels; therefore it needs not the strict scale but the unified production standards. Map symbol usually imitate the real world as much as possible and sim

15、plify itself at the same time. The scope of the screen is far greater than the fixed vision of papery maps. Cartographic generalizations think much of the balance between the abstract model and the actual performance results.As for the data acquisition and management, such as the introduction and th

16、e information users obtained from the map are final results of data acquisition. In the beginning, we collect the needed data including the name, the address, the introduction and the digital photos of the buildings and prepare for the subsequent three-dimensional modeling. After collecting the data

17、, we should pay attention to archival and backup the files in case of loss. In order to get the map, a good preparation of the design of the standard scene is necessary. We set the parameter of the underlay, lights, altitudes, render effects and so on, so as to ensure the final fruit of our effort w

18、ill have a uniform effect. The spatial entitys performances usually show up as the form of spot, line and surface in the three-dimensional electronic map. Compared with vector graphics, the grid graphics have unparalleled advantages. The combination of the grid graphics and the WEBGISs background pu

19、blishing technology can improve the response speed of system and save systems inputs. System achieves the interaction with the map with the JavaScript languages. Seeing that there lie differences in supporting the scripting languages on various browsers, testing all kinds of functions by different b

20、rowsers is a crucial step.IV. KEY TECHNOLOGIESThe developments of three-dimensional electronic maps are inseparable with the development of related areas, and it learns research methods, techniques and tools from other areas. While the researches of other areas are directly applied to the developmen

21、t and construction of three - dimensional electronic map, and Computer graphics, 3-D GIS, Virtual Reality and Geographic Data Base, the modeling of virtual scene and so became the technical support of the three-dimensional electronic map system. The WEBGIS technology on which three-dimensional elect

22、ronic map system of campus based is a standard Software technology which means without any commercial softwares support. During the development of the system we make use of the common available technology which includes the JavaScript technology, Ajax technology, XML technology, etc. Ajax is not a o

23、ne fold technology, it is a mixture which mixes multiple technologies together, including the document object which used to display on the web and its hierarchical structure document object model DOM, and CSS that used to define the elements of style, and data exchange format XML or JSON, implementa

24、tion and asynchronous server of XMLHttpRequest and client script language JavaScript 3. Ajax takes advantage of non-synchronous interaction technology which means there is no need to update pages; therefore, it will lessen the users waiting time both psychologically and physically. That is why it wi

25、ll be easier to be accepted by public.EXT is an excellent Ajax framework written in JavaScript; it has nothing to do with the back-end technology and can be used to develop rich client applications with a gorgeous appearance. The system enables the EXT combined with JSP to achieve the other page fun

26、ctions of the electronic map. The system combines the EXT with the Prototype whose framework bears the burden of creating a rich client and a highly interactive Web application, which realizes the application of the rich client efficiently and manage the safety of the client in a safe way that could

27、 be controlled. JavaScript is the principle technology of the system during the design and the implementation process. It allows a variety of tasks which can be completed solely on the client, and without the participation of the network and server which used to support the distributed computing and

28、 processing, and therefore reducing the invisible waste of resources. JavaScript allows neither the access to the local hard disk, nor the data to be saved to the server, let alone to modify and delete network documents. The single way to browse the Web information and realize dynamic interaction is

29、 through the browser, which can effectively guard against the data-loss, consequently the system reaches a high security coefficient. JavaScript can be used to customize the browser according to the diverse users, the more user-friendly the design of web pages is, the easier the method for the users

30、 to master. JavaScript technology means through the small-block approach to realize the programming. Just as the other scripting languages, JavaScript is also an interpreted language; it offers a convenient development environment.In this system, we take advantage of JavaScript scripting language to

31、 realize the key functions such as loading maps, zooming maps, geographic location, and other related auxiliary functions, i.e. map icon display, ranging, eagle eye, tags. Oracle database meets the need of the data which is used in backstage management, and together with the JSP, XML and HTML to rea

32、lize the users authentication as well as adding, deleting, revising and inquiring informations, etc. The main function of the system is to realize the three dimensional electronic map displayed in the browser through WEBGIS technology. Owing to the combination of JavaScript technology and WEBGIS dev

33、elopment model, we can reduce the cost of the system, and at the same time improve the interoperability and system performance. Thanks to the application of AJAX technology, we can make further improvement on loading dynamical map. All the technologies we use will reduce the reaction time, which will leave a quick and effi