The Design And Implement Of Oblique Photography 3D Model Visualization Solutions Based On WebGL

Since the high efficiency and large-scale features of 3D Model by the oblique photographic technology,this technology has been used in the production of data widely more and more,the oblique photography become an international frontier hot issues.Current research mostly concentrated in data processing,production model,but with the development of Web3 D technology,the visualization research of 3D model data of oblique photography has more application of practical requirement based on B / S structure.But becauset the subject of Web3 D technology bottleneck,the traditional 3D WebGIS browser has been install plug to observe 3D graphics,and its defects such as low render,could not suffice today's 3D WebGIS system and user demand.This paper studies the 3D model of oblique photography data content and data structures and spatial data visual process of Web3 D technology based on Web GL technology.Design and implement a visualization program which adapted for 3D WebGIS inclined 3D model of oblique photography,its should ensure efficient scheduling and smooth rendering of the 3D model of oblique photography in scene of 3D WebGIS.The main contents are as follows:(1)Study of modeling method for 3D model of oblique photography and data structures;study the 3D Web GIS visualization technology of geospatial data,compared to conventional Web3 D technology and 3D rendering engine based on WebGL,summarize their advantages and disadvantages.Expound the significance and development trend of WebGL for 3D WebGIS.(2)Design a visualization program for oblique photography 3D model.An interchange format BGTLF of 3D model based on JSON,comparing the difference between the characteristics of the format and several other standard formats,developed a batch of data preprocessing process and reconstruct the file structure and metadata file based on quadtree.(3)Optimization model rendering based on the traditional method of scene painting,paper add a set of frustum bit mask,according the records to reduce the number of traverse each surface of frustum when the frustum change so accelerate the process of model render.(4)Study the 3D system visualization space that is frustum and its projection.Research the several accelerate mechanism of data schedule,the data prefetching mechanism based on the viewpoint,the three-level cache mechanism combined with HTML5 cache,combined CPU and GPU for Multi-threading mechanism;the visibility culling methods and WebGL rendering mechanism combined for scene updates.The paper adopt the JAVA and JavaScript language for the development,based on B / S structure,combined 3D model data of oblique photography,terrain data,map data with OGC standard services,design and implement 3D model data of oblique photography display system,and verify the feasibility by the above programs and technology.