中文摘要：

矢量地图渐进式传输的关键技术是建立连续的多尺度表达模型,并在服务器端将地图数据组织成线性结构。提出一种用于网络环境下的等高线渐进式传输模型,此模型以曲线的傅里叶形状描述子构建数据流,在客户端以先期到达的低频参量构建等高线的形状轮廓,其后依次到达的高频参量不断＂完善＂等高线形状细节,从而实现等高线由粗到精的渐进式传输。该模型的应用具有两大特点：其一,傅里叶形状子数据流与由坐标构成的数据流相比数据量大为降低,能减少数据的传输量;其二,能够实现连续尺度的地图要素的渐进式传输与表达。另外,本文还建立了不同等高线的傅里叶展开项数与比例尺的匹配方法,探讨等高线傅里叶形状子的提取、传输,以及客户端重构的细节。

英文摘要：

The key technology of progressive transmission for vector map is the model establishment of successive multiple representations of spatial data and the line-structure organization of map data in the server.An algorithm for progressive transmission of vector contour data on the internet was brought,which built data-stream using Fourier-descriptor,then rough sketch of contour was restricted with the initial low-frequency data,and gradually the detailed part of contour would be added by higher-frequency data on the browser site,so the progressive transmission and representation of contours could be achieved.The application of the model has two main characteristics.First,what was transmitted on the internet was feature vectors extracted from curves by Fourier series,which played an important role in data compression.So the amount of data was reduced compared to coordinate data as the consequence.Second,continuous scale map representation could be achieved with the model.Furthermore,the match model was provided between the number of terms of expanded Fourier series and the scale of contour and researched some technical details on the extraction,transmission of Fourier descriptor and reconstruction of contour on the browser site.