| Urban landscape architecture has many functions,such as balancing ecology,creating culture,enriching society and aesthetics.Scientific and reasonable landscape organization is an important part of urban construction.The research of 3D landscape construction,landscape visualization and immersive virtual display has become the research hotspot in the field of landscape simulation and virtual reality technology.Because of the complexity of the scene and the unobvious spatial regularity,the landscape scene with rich landscape elements has difficulties in the construction to some degrees,organization and virtual display of3D scene.Specifically,the traditional 3D landscape construction and the virtual display include problems,such as the inflexibility of landscape space organization,the limitation of virtual landscape simulation used in reality,and the large workload of landscape vegetation and architectural models’construction.Based on the mentioned problems above,this paper integrates the techniques of virtual reality,virtual plant and geographic information system,and integrates parameterized plant modeling method,virtual reality immersive technology to research the overall process of parameter-driven virtual landscape synthesis construction,organization and exhibition.The main research contents and results are as follows:(1)Constructing 3D Model of Landscape elements.The main elements in the landscape are modeled.By using the parameterized plant modeling method,according to the measured tree morphological and structural parameters,the landscape tree model of different tree species with high realism is constructed quickly and easily,and Billboard nodes and level of detail model(LOD)nodes of the tree model is added to the tree model to improve the efficiency in landscape rendering;The 3D digital terrain model of garden is constructed by using topographic point cloud data,the real-time fluctuating water body model is constructed by OpenGL shader language,and the Fresnel dynamic optical reflection effect of water body is achieved based on identifying ray direction.In addition,the batch building model,sky background model and other landscape scene models are constructed.(2)Putting forward the concept model of 3D modeling and virtual exhibition system for garden landscaping,and the 3D visualization of the whole landscape is achieved.Based on OpenSceneGraph(OSG)engine,various 3D landscape models are visualized.Through the digital vector layer,and through managing and organizing landscape elements,we realize all kinds of garden landscape space layout parameter control,as well as the spatial topological relationship between all kinds of landscape in 3D scene is reasonably organized.By integrating cross-platform ArcGIS Engine components,basic landscape scene data including terrain data and vector data are managed.The rendering efficiency and real-time performance of the landscape is improved by the techniques of scene clipping and level of detail model.The interactive three-dimensional scene browsing is achieved,and the six-degree of freedom of the whole landscape is presented.(3)Immersive virtual display for3D landscape.Based on the OSG engine and Oculus Rift virtual reality equipment system,the scene data transfer from the whole 3D landscape to the virtual reality helmet display equipment system is actualized.With the support of Oculus SDK,the second rendering of the whole 3D landscape scene in the immersive virtual reality module is carried out,and the corresponding OSG camera browsing interface is constructed.A binocular immersive virtual display of three-dimensional landscape architecture is achieved,which provides help for the connection between virtual landscape and reality.Meanwhile,according to the demand of real-time rendering of virtual reality and programmable rendering pipeline technology,the feasibility of GPU accelerated rendering based on OpenGL Shader Language in the landscape tree vegetation rendering process is researched. |
