基于FME的规划数据格式转换研究

传统的城市规划成果主要是以CAD格式为主,但这种格式数据对属性信息表达不够完整,难以与实体相连接,导致数据查询、统计、分析困难,GIS空间数据库技术能有效地解决这些问题。本文从分析两种数据格式的特点着手,通过介绍传统的从CAD到GIS格式的转换方法及缺点,进而提出利用FME软件实现规划数据从CAD到GIS格式的无损转换。     

三维地形可视化中不同图元渲染效率比较分析

大规模地形场景一般由几百万甚至更多的顶点构成,地形瓦片的图元组织与绘制效率直接决定了地形渲染的速度和质量。为明确Triangles,Triangle Strip,Triangle Fan和优化的Triangle Strip图元渲染效率,选取常用的11种大小瓦片样本进行对比试验。从初始化时间、索引缓存大小和实时绘制时间3个方面评估图元效率。结果表明：在地形瓦片小于256时,Triangles和优化的Triangle Strip具备较高的渲染效率,Triangles会占用较大的索引缓存;在地形瓦片超过256时,优化后的Triangle Strip图元具有最高绘制效率,并且占用最小的索引缓存。     

水准路线图自动绘制实现方法

本文以某工程为例,介绍了水准路线图绘制方法,并编制自动绘制软件。软件可根据提供的点位信息自动绘制标准图幅的路线图,并具有点位标定准确、图幅信息完整、界面整饰美观的特点,同时极大提高了作业效率。     

降雨量等值线图的自动绘制方法

针对当前等值线自动绘制方法中存在的不足,该文以四川区域降雨量为例,分析降雨等值线的特点,依据计算机自动化等值线绘制的基本原则,给出了降雨量等值线的网格区域插值、等值线追踪、等值线平滑和等值线标注整个自动绘制流程的算法设计与具体实现。实验证明该方法易行、准确,可以拓展到更多的等值线绘制领域。     

折射波时距曲线及解释剖面的自动绘制

本文提出并解决了折射波时距曲线及解释剖面的自动绘制问题。通过自动的绘制，输出美观、准确的时距曲线及解释剖面，避免了清绘等过程，节省了大量的人力、物力。     

Systems for Hazards Identification in High Mountain Areas： An Example from the Kullu District, Western Himalaya

Methods and techniques for the identification, monitoring and management of natural hazards in high mountain areas are enumerated and described. A case study from the western Himalayan Kullu District in Himachal Pradesh, India is used to illustrate some of the methods. Research on the general topic has been conducted over three decades and that in the Kullu District has been carried out since 1994. Early methods of hazards identification in high mountain areas involved intensive and lengthy fieldwork and mapping with primary reliance on interpretation of landforms, sediments and vegetation thought to be indicative of slope fail ures, rock falls, debris flows, floods and accelerated soil surface erosion. Augmented by the use of airphotos and ad hoc observations of specific events over time, these methods resulted in the gradual accumulation of information on hazardous sites and the beginnings of a chronology of occurrences in an area. The use of historical methods applied to written and photographic material, often held in archives and libraries, further improved the resolution of hazards information. In the past two decades, both the need for, and the ability to, accurately identify potential hazards have increased. The need for accurate information and monitoring comes about as a result of rapid growth in population, settlements, transportation infrastructure and intensified land uses and, therefore, risk and vulnerability in mountain areas. Ability has improved as the traditional methods of gathering and manipulating data have been supplemented by the use of remotesensing, automated terrain modeling, global positioning systems and geographical information systems. This paper focuses on the development and application of the latter methods and techniques to characterize and monitor hazards in high mountain areas.     

利用FME的小城镇规划数据集成方法

多源数据集成和共享是实现区域规划的瓶颈问题。本文提出利用XDATA扩展数据的方法满足信息量需求,并针对数据集成过程中要素丢失等现象,编写VBA代码实现源数据的质量控制;提出利用FME重新定义数据以实现多源数据的语义转换和集成数据字典模式统一数据编码的数据集成方法。研究表明,该方法符合数字化、信息化测绘和管理数据的发展要求,能够提高数据生产和应用的效率,是一种实用且值得推广的方法。     

利用dxf格式实现CAD图形坐标转换方法探索

DXF格式文件是CAD图形的纯文本文件形式,通过对该文件的处理,可以实现CAD图形不同投影带、不同坐标系之间的图形转换。其原理就是对DXF格式文件中CAD图形包含的点、线、面等定位点坐标值,根据选择的数学模型进行逐点处理,从而达到对整个CAD图形转换的目的。