Research On Quasi Realistic Display Technology Of Buildings Based On 2D/3D Hybrid

Three dimensional GIS compared to the two dimensional GIS can be more three-dimensional and more realistic expression of spatial objects. With the popularity of mobile devices, mobile three dimensional GIS technology research has become a hot topic in today's research. But the two dimensional GIS has been widely used in land management, urban planning and other fields and it has accumulated a wealth of data resources. How to use the existing two dimensional data to quickly establish three dimensional data, give full play to their respective advantages and disadvantages and achieve mobile terminal two or three dimensional interactive display aiming at building data is studied. The details are as follows:The data model of three dimensional building is studied. Combining with the research results of the existing three dimensional data model theory, an object-oriented three dimensional building data model is designed aiming at fast display and clear representation of spatial information. A three dimensional data model based on the existing two dimensional data is proposed, which can speed up the establishment of three dimensional data and avoid the waste of the existing two dimensional data and the discontinuity of the two or three dimensional data management. Combining ArcGIS and SketchUp, the establishment of three dimensional building model is completed, and the organization and management of three dimensional building data based on surface classification are realized by using object-oriented idea.Research and design of embedded database based on spatial data storage. Based on the limitations of the software and hardware resources of the embedded platform, the R* tree index module of the lightweight embedded database SQLite is turned on. At the same time, the Android platform using the index to quickly access the spatial data of the database storage method is achieved. Data retrieval speed is increased by 80%. Thus it provides guarantee for accelerating data rendering in data organization. Combined with the characteristics of spatial data, the storage mode of building data is designed and the integration of the two and three dimensional building data storage is realized.A real-time rendering algorithm of three dimensional scene based on embedded platform is studied. A three dimensional scene with a sense of perspective is built by using the embedded 3D drawing database OpenGL ES. A triangulation algorithm based on polygon constraint is designed. The triangulation of concave polygons and complex polygons with holes is realized. Through the three-dimensional object model transformation, view transformation, clipping transform and adding the scene light, three dimensional rendering of three dimensional objects from 3D scene to 2D screen is completed. Through the test of rendering efficiency, the 2D/3D interactive display mode is proposed. The planar shadow algorithm is designed to increase the quasi true display of the 3D scene.An interactive visualization software for 2D/3D building is designed and developed. Combined with the two and three dimensional visualization of their respective advantages and disadvantages, a 2D/3D interactive display mode is designed to improve the rendering speed. Defining the corresponding rules of gesture set and map operation, the recognition of gesture operation type is realized, and then the three-dimensional scene of the translation, scaling, rotation transformation is realized. A 3D picking algorithm is implemented to complete query function of the three-dimensional scene by researching 3D pickup technology and AABB bounding box principle.The key technology of the interactive display of 2D/3D building under embedded platform is realized. The design and development of the interactive visualization software based on Android is developed, which has higher efficiency and better function.