可编辑三维场景的动态3D Tiles构建方法  

Construction method for dynamic 3D tiles in editable three-dimensional scenes

作　　者：马林兵[1] 代兴龙 胡靖元 MA Linbing;DAI Xinglong;HU Jingyuan(School of Geographical Science and Planning,Sun Yat-sen University,Guangzhou 510006)

机构地区：[1]中山大学地理科学与规划学院,广州510006

出　　处：《时空信息学报》2024年第4期500-512,共13页JOURNAL OF SPATIO-TEMPORAL INFORMATION

基　　金：广东省基础与应用基础研究基金项目(2022B1515130001)。

摘　　要：可编辑的大型三维WebGIS具有一定的应用场景需求,常见的3DTiles数据格式局限于静态场景渲染,在编辑的三维场景中,需要构建动态的3D Tile文件格式和多细节层次(level of detail,Lo D)渲染方法。本文从动态空间索引和多细节层次技术两方面研究Web在线编辑大型三维场景的构建方法,将动态松散八叉树和半边折叠LoD构建算法应用于3D Tiles构建流程中,实现支持可编辑场景的3D Tiles构建与更新。结果表明:(1)松散八叉树索引在计算量上能够实现动态更新的目标,且在视锥体剔除上有着良好的精度;(2)基于半边折叠法进行准实时LoD的构建,能够满足动态场景下实时计算LoD的需求;(3)所构建的3D Tiles场景,配合Three.js等成熟框架并应用WebWorker等技术,能够顺利完成3DTiles的高效调度和渲染。研究成果对城市三维模型在线编辑、动态地理三维场景的加载渲染等相关研究和应用具有一定的参考价值。The integration of Web-based 3D rendering technology with geographic information systems(GIS)has emerged as a significant trend in the evolution of 3D GIS.Notably,Web 3D scene visualization and editing technology have attracted considerable attention,given that editable large-scale 3D WebGIS applications are contingent on specific usage scenarios.This paper delves into the methodology for constructing editable large-scale 3D scenes,focusing on dynamic spatial indexing and multi level of detail(LoD)techniques.It introduces the dynamic loose octree and half-edge folding LoD algorithm to the 3D Tiles construction process.In terms of model rendering precision,the spatial index built upon the loose octree offers superior rendering speed compared to the conventional octree.During dynamic model editing,the time investment required for generating quasi real-time LoD using the half-edge folding algorithm remains relatively low,while still delivering commendable frame rate performance and ensuring satisfactory model simplification outcomes.In conclusion,the paper presents the development and refresh of 3D Tiles that support modifiable scenes,showcasing experimental results that amalgamate three-dimensional artificial models,architectural data,mountain models,and the Stanford dragon model.Findings indicate that:(1)the loose octree index adeptly meets dynamic update demands in terms of computational burden,exhibiting impressive precision in frustum culling;(2)the creation of quasi-real-time LoD via the half-edge folding technique adequately addresses the computational needs of LoD requirements in dynamic environments;(3)when integrated with established frameworks like Three.js and employing technologies such as Web Workers,the resultant 3D Tiles scene facilitates efficient task scheduling and rendering of 3D Tiles.The Web-based 3D scene editing approach introduced in this paper lowers user barriers,amplifies interactivity and flexibility in 3D GIS applications,and fosters broader adoption of 3D GIS across diverse sectors.Thi

关 键 词：3D Tiles 松散八叉树 空间索引 LOD 三维地理空间数据 三维渲染 WEBGIS 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]