【正文】 DMAX whose operation is simple and flexible to model. Given the later needs of electronic map, the threedimension model should be delicate as much as possible. The three dimensional model39。t escape. With the technical and cultural constantly progress, the form and the content of the map change and update as well. As the puter 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 e into being is the emap [1]. With the rapid development of the puter technology, puter graphics theory, remote sensing technology, photogram metric technology and other related technology. Users require handling and analysis of threedimension visualization, dynamic interactivity and show their various georelated 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 threedimensional electronic map. II. FUNCTIONDESIGN Threedimensional electronic map system of campus based on WEBGIS has general characteristics of the mon 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 map39。 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 plete 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 plete 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 bined can plete 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 pletion 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: ( / oldpercent) * newpercent. ? Modify icon data in the icon layer (Icon layer logical operationCmap _ ). ? Remove the current map layer, and force the memory recycling. ? Load required map file. 內(nèi)蒙古工業(yè)大學(xué) 本科畢業(yè)設(shè)計(jì) 外文文獻(xiàn)翻譯 8 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 popup boxes For some hotquery 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 the stadium, the building has no change, but when moving the mouse over the stadium, the outline of the building shows. When click the highlight of the stadium, the stadium will pop up some basic information’s, such as the stadium office phone, address details, the basic profile. 2) Range As a result of mutual conversion between longitude and latitude and the campus electronic map coordinate, we can first transform campus electronic map coordinate to the latitude and longitude coordinate, then calculate the distances between two spots through their latitude and longitude coordinates, this way is simple and precise. 3) Label display and hide In order to prompt some key places in the map (such as public transportation station, street sign ), using the new layer in its label tagging, it is convenient to the user for recognize specific location, but the tagging information will affect the whole scene showing, so the user can choose displaying labels when in needed. 4) Realtime coordinate and eag