Research On Some Techniques Of Interactive Designing Of 3D Landscape

Research on some Techniques of Interactive Designing of 3D Landscape,which put forward from the requirements of the visualization of the earth's multi-information and the three-dimensional virtual construction or engineering design,has a close relationship with three of the most popular research points :the technique of 3D visualization,the technique of virtual reality or scene emulation and the technique of 3DGIS.In this dissertation,for the requirements of application,three related aspects about interactive design of 3D Landscape are studied,which are the visual modeling methods of 3D landscape,the key algorithms of the realization of 3D interaction technique and a prototype system--VisualScene.Firstly,the dissertation probes some problems of the current 3DGIS data models,then the author gives a brief introduction of the conception.the formation and simple production algorithms of DEM in terrain landscape and constructs a real terrain landscape by experiment.As for the constructions.the author dissects the feature of constructions and expounds how to model 3D constructions based on 2D data and the modeling method for complicated constructions.Based on the feature of house,such as data source ,obverse, profile etc. Using the data structure and texture mapping techniques in this thesis.a real 3D house can be erected.On plants modeling,an appraisal is made for the mostly used plants modeling and rendering methods.Trees can be modeled by mipmap method , moreover,this method can also be used to model flowers and potted landscapes.For the design of prototype system, efficient 3D interaction algorithms cann't be omitted,because the system's function and utility are determined by them at large extent.As for the difficulty of 3D interaction,the author designs his own 3D interaction algorithms.which using quaternion to stand for rotation status and mouse trackball algorithm to realize three-dimensional rotation.On the other hand.two kinds of realtime interactive rendering of terrain model are presented.By OpenGL programming.direct light.point light and spot light are visualized in shape to simulate the light of our environment.ln this way.a more real scene can be displayed in the computer ,furthermore,the light can be controlled by the user.Finally, in order to test and verify the modeling method,the rendering techniques of real graphic and the key algorithms of three-dimensional interaction ,a tool Real3DM for 3D modeling and interaction is developed using Visual C++6.0 &OpenGL and COM technology on the platform of Windows 2000.Using this tool,a prototype system for Interactive Designing of 3D Landscape named VisualScene is also developed.Experimental results show the reasonability and practicability of the modeling methods and the key algorithms for 3D interaction.