Architectural Point Cloud Model Rendering System Based On WebGL

With the gradual development of 3D laser scanners,architecture point cloud is applied to practical applications in the reverse engineering of Architecture,especially for historic buildings.Point cloud data records accurate building structure information,while colored point cloud data records architectural details and textures.However,the existing professional point cloud software is mainly based on the PC.It not only has high hardware requirements and is expensive,but also lacks point-to-face architectural displays.Point cloud is a collection of sampling points on the surface of the building,so the display of point set cannot render the building surface.Therefore,it is of great practical value and research value to realize the use of large-scale point clouds and the display of point-to-face architecture on the Web.Starting with the study of scene management of point cloud model and point-to-face rendering algorithms,this paper analyzes the use of large-scale architectural point cloud model and the display of the surface of the architectural model.The main research work includes: analyze the characteristics and scene management methods of architectural point clouds,and study the domestic and foreign research results related to point cloud rendering algorithms and architectural model reconstruction algorithms;in order to solve the memory load and rendering efficiency problems of large-scale point cloud,an octree-based level of detail algorithm(LOD)is proposed,on which the LOD selection strategy based on the projected area and distance reduces the loading of occluded nodes under the guarantee of display effect.learn the relevant knowledge of WebGL rendering pipeline and spatial transformation,and improve the EWA Splatting framework to implement point-based rendering algorithm on the web.In order to display the surface model of some buildings,an architectural model construction algorithm is designed.The flow includes calculating normal vector,extracting geometric features,constructing the grid model and optimizing the grid model.Based on research work above,a WebGL-based architectural point cloud model rendering system is designed and implemented to realize the use of a large-scale architectural point cloud and display of architectural models.The system adapts multiple platforms,and compares with the same type of softwares on the memory load and the rendering frame rate based on multiple data sets.The experimental results show that the rendering system use point cloud data to provide convenient tools and a three-dimensional display for Architecture.