计算机毕业设计方案外文翻译.doc

学校代码： 10128学 号： 2076 本科毕业设计外文文件翻译（题 目：The Design and Implementation of 3D Electronic Map of Campus Based on WEBGIS学生姓名：张 天 佑学 院：信息工程学院系 别：计算机系专 业：计算机科学和技术班 级：计算机09-2指导老师：庄 旭 菲 讲师 贾 然 工程师二 一 三 年 六 月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 penetrated 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 systems (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 promising 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 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-dimensional 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 translation. 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 depict 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 information. 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 system 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, 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 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 function 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 electronic 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 simplify 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 the 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, 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 will 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 publishing 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 browsers 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 development 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 electronic 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 one 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, implementation 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 will 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 functions 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 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 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 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 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 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 realize 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 development 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 efficient impression on users.V. THE IMPLEMENTATION OF THE SYSTEMA. The fabrication of the three-dimensional scene and scene rendering for map.The three-dimensional electronic map of campus based on WEBGIS, is an electronic map system which takes the Northeast Petroleum University as the prototype. To realize this system, we should complete the fabrication of three dimensional scene and scene rendering for map, so we select 3DMAX whose operation is simple and flexible to model. Given the later needs of electronic map, the three-dimension model should be delicate as much as possible. The three dimensional models construction would take up a great deal of time, due to so many complicated buildings of Northeast Petroleum University. To complete the three-dimensional scene we should first prepare to render the scene well. Actually the grid picture which three dimensional electronic map used is the fixed angle of view swivel eye grid map. After modeling of three dimensional spatial entities, select the appropriate rendering method and make a fixed camera angle positioning in the render (Normally at 45-degree angle ), and then set the render output parameters to render them into the camera from the perspective of fixed size picture4. B. Loading Map In the WEB, the maps are mainly shown through the Div layer which has three layers. One layer is used as a window the carrier of the map. The size of the layer is as large as the map which we usually see through the browser (referred to as the window layer). Another layer is the moving layer used to follow the drag of the mouse (referred to as the moving layer).The other is the covering layer which lies between the window layer and the moving layer. The map window operated by users is constituted by the three layers mentioned above. Basic operations of the map are realized through setting features in different layers 5. When loading map, we use the raster data which we usually call image data. Raster data includes image data, two dimensional map, and three-dimensional simulated electronic map. The raster data in this system is three-dimensional simulated electronic map. The abstract two-dimensional map makes some ordinary users difficult to learn the information they need, but the three-dimensional simulated map simulate the real worlds information exactly, so users can easily see the real world. This system mainly displays the map picture, when you view or drag the map, it just like a complete map picture of the current window, but in fact patchwork of small pictures. These small cards are cut from complete map by the specific cutting diagram program; all the picture cards are the same size and have fixed naming rules, so the map is faster and easier to load. There are many methods to complete the map carving, the system use square slab method to cut the map to 256 pixels * 256 pixels. Then write the script which based on the naming rules to complete the picture load.C. The Basic Function of Map Dragging, zooming and translation are the basic functions of the map, and they are also important features of the map that differ from a simple picture. The following is a brief description of the implementation method. To realize dragging, the first thing is to set the mouse event functions. The events include mouse down and mouse up. So the two functions combined can complete the map navigation. The mouse down event is mainly used to record the drag state as well as the present location, while the mouse up function will capture the dragging completion status, then use show map function to reload maps. Process of realizing zooming function as follows: Gain ratio value before amplification and the proper ratio value needed to enlarge. Calculate the coordinates of the center of the map after amplification. The formula: (point.x / oldpercent) * newpercent. Modify icon data in the icon layer (Icon layer logical operation-Cmap _ Base.js). Remove the current map layer, and force the memory recycling. Load required map file. With these basic functions, the user can observe the entire campus buildings concisely and clearly. The map is divided into five zoom levels, users can zoom out to view more buildings, also can zoom in to examine the architectural details.D. Other Utility Functions 1) Highlight and pop-up boxes For some hot-query buildings, we use JSON data to create a div layer, filled with color, and then set to translucent, when the mouse moved to the layer, this area will be highlight selected. When Mouse clicks on the highlighted area, a small window will pop up showing the architectural details. Take the stadium as an example, when the mouse is not over t