| The development of computer technology brings a lot of convenience to social life. Virtual reality is comprehensive technology which synthesizes modeling technology, computer technology, graphics technology, and has 3I including Immersion, Interaction and Imagination. It is widely used in education, military, medical treatment and so on. Virtual reality modeling language (VRML) can create virtual 3D scene in which users can roam, watch and experience facilities to enhance immersion. But when a user freely walks, he often has lost feeling that he does not know where he is. With the rapid development of science and technology today, 2D electronic map is widely used because of its plane, macro, and integrity, but it can not completely reflect the objective world.The paper will complement the reality,part and visualization of 3D virtual scenes with the macro, integrity and terseness of 2D electronic map. 3D virtual scenes are created by VRML and with geometry model and the image hybrid modeling technology, and realize automatic and interactive roaming. The collision detection avoids penetrability, running into the underground and so on to enhance reality. Large-scale virtual scene executes better by reusing mechanism, reasonably using texture and LOD. On the one hand VRML uses touch sensor and perception sensor as non programming way to realize interaction itself, on the other hand it can use JSAI, EAI or JS interface as programming way to realize interaction of VRML scene and external environment.The paper adopts EAI external programming interface and embed Java Applet and VRML files into HTML pages together to realize mutual response between 3d virtual scene and 2D electronic map. The expression of mutual response has two kinds. Firstly, 2D electronic map displays real-time position when users roam in the 3D virtual environment. Secondly, the viewpoint jumps to the corresponding position in 3D virtual scene when users change the position in the 2D electronic map. |
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