Research On Web-Based Visualization Technologies Of Massive Oblique Photogrammetry Models

In recent years,with the rapid development of UAV technology and the maturity of oblique photography 3D reconstruction technology,the technology of acquiring images from drones and finally forming a 3D model of oblique photography has been improved.At the same time,the continuous innovation of Web technology,the emergence of HTML5 and WebGL opened the way for creating a new Web-based application,and also brought an opportunity for the application of the oblique photography model.There is an increasing demand for visualization of massive oblique photography models using the B/S architecture.However,the oblique photography model is generally used to display urban scenes.As the city scale expands,the amount of data in the model increases,reaching tens of gigabytes to terabytes.The oblique photography model has such a large amount of data and complex data structure that it is difficult to directly render,and it cannot be loaded into the memory,and there is no data format suitable for network transmission,browser fast parsing,data scheduling transmission strategy,Memory management strategy,so when browsing the model data through the webpage,there will be delays in client rendering,or insufficient memory in the browser.Based the above problems,this thesis deeply studies the visualization technologies of Web-based massive oblique photography model.The main work is as follows:1.In order to realize the fast transmission,analysis and rendering of Web-based massive oblique photography model,a block-based tile pyramid model is proposed.The multi-resolution detail hierarchy is organized and a Web-oriented 3D tile format is designed,using a data format that can be efficiently transmitted and parsed.2.In order to realize the rapid visualization of massive oblique photography model based on Web,a dynamic scheduling technology based on viewpoint is proposed.Depending on the viewpo int parameters,the invisible tiles are quickly removed,and the tiles with different resolution levels are selected for display.3.In order to solve the problem that massive oblique photography model cannot adapt to system memory,a dynamic scheduling and visualization method based on viewpoint and external memory is proposed,which combines memory management technology with data scheduling method.In addition,different improvement strategies are proposed for different data and different types of termina l devices.4.By comparing and analyzing the digital earth platform of different B/S architectures,a Web-based massive oblique model visualization platform framework is proposed.The prototype system is designed to realize the visualization of massive oblique photography model and expand other functions.