基于TMS的数字孪生城市分层影像数据实时绘制方法  

A Real-time Rendering Method of Layered Image Data in Digital Twin City Based on TMS

作　　者：罗德宁 刘启虞 郭德全[1] LUO Dening;LIU Qiyu;GUO Dequan(School of Automation,Chengdu Univ.of Info.Technol.,Chengdu 610255,China)

机构地区：[1]成都信息工程大学自动化学院,四川成都610255

出　　处：《工程科学与技术》2023年第6期39-45,共7页Advanced Engineering Sciences

基　　金：四川省科技计划项目(2022NSFSC0934);四川省重点研发项目(2023YFG0122);成都市科技项目(2022–YF05–01134–SN);成都信息工程大学基金项目(KYTZ202141);国家留学基金管理委员会(CSC201806240168)。

摘　　要：3维地形绘制在军事、农业、交通、智慧城市等众多行业中应用广泛,其中影像数据的处理方式主要采用空间网格划分和建立不同层级的瓦片数据。为了提高3维地形的分辨率,切割的瓦片数量呈指数增长,海量瓦片数据的访问、索引和绘制的技术难题,本文提出了一种基于TMS(tile map senice)的分层影像数据实时绘制方法,避免不同层级影像衔接处出现严重色差;构建不同影像层的服务对象,并实现大量数字孪生城市分层影像的层级、顺序、位置的灵活控制管理;根据视口中的加载瓦片的相对优先级,存入高、中、低3个队列,以加速瓦片数据的调度与绘制。为了加速影像瓦片索引获取,根据视口内的瓦片矩阵范围计算屏幕像素大小,获取影像瓦片的初步层级后与当前文件资源的层级比较确定影像的最终层级,计算视口内影像瓦片的索引和根据经纬度、层级计算行列号,从而形成影像资源的请求路径。在多层影像绘制过程中,根据影像层级大小依次从最底层开始两两图层依次混合,得到正确的混合结果。本文针对实际应用中的近、中、远景及沿海等多层影像数据进行了3维地形绘制实验,结果表明,在NVIDIA 2070显卡上能够达到300 FPS的高实时性能,并且达到无影像层级色差且高质量的绘制效果。本方法能够灵活地绘制大规模多层级影像数据,构建出数字孪生城市场景的3维地形。The 3D terrain rendering is widely used in many industries,such as the military,agriculture,transportation,and smart cities.The processing method for image data mainly adopts spatial meshing and establishes tile data at different levels.In order to improve the resolution of the 3D terrain,the number of sliced tiles is increasing exponentially,and the accessing,indexing,and rendering of massive tile data are technical problems that need to be overcome.In this paper,a real-time rendering method for layered image data based on TMS(tile map senice)was proposed to solve above problems and to address the severe chromatic aberration at the junction of different levels of images.In this method,service objects with different image layers were constructed,and the flexible control and management of the hierarchy,order,and position of digital twin city hierarchical images were realized.Meanwhile,three queues were stored for high,medium,and low relative priority of the loaded tiles in the viewport to speed up the scheduling and rendering of tile data.To accelerate the acquisition of image tile index,the screen pixel size was calculated according to the tile matrix range in the viewport.The final level of the image was determined by comparing it with the level of the current file resource after obtaining the preliminary level of the image tile.Then,the index of the image tile in the viewport was calculated,and the row and column number were calculated according to the latitude,longitude,and level to form the request path of the image resource.Finally,the two layers were blended sequentially from the lowest layer to obtain the correct blending result according to the size of the image hierarchy.In the paper,a set of 3D terrain rendering experiments were carried out on near,medium,far,and coastal multi-layer image data in practical applications.The results showed that the NVIDIA 2070 graphics card can achieve high real-time performance of 300 FPS and high-quality rendering.Therefore,the proposed method can flexibly render large-

关 键 词：数字孪生城市 分层影像数据 3维地形绘制 瓦片数据 实时绘制 

分 类 号：TP391.9[自动化与计算机技术—计算机应用技术]