基于PostScript成像模型的点状地图符号设计与实现

针对当前GIS软件中矢量符号精度低下、共享困难等问题,引入Post Script成像模型中图形描述机制,设计了基于该模型的地图符号,详细介绍了模型支持下点符号数据结构以及符号制作、入库和符号化过程等,并开发了基于Post Script语言的符号库和地图制图系统。实验表明:基于该模型的地图符号具有较高的精度和较好的通用性。     

地形图图廓整饰的设计与实现

图廓整饰是地形图的重要组成部分,也是地图输出过程中的一个重要环节。针对现有软件生成图廓整饰缺乏标准性和灵活性的问题,文中分析不同比例尺地形图图式规范,归纳总结出图廓整饰的内容,并根据图形特征与位置分布加以分类。在此基础上提出一种设计方案,通过对每个整饰要素定义相对坐标系和添加参数属性的方法,可以实现整饰要素的精确生成以及灵活调整。根据设计方案进行相关开发予以实现,实践结果表明,该方案确实有效,能实现地形图图廓整饰的自动化生成,提高制图工作效率。     

Chain-based polyline tessellation algorithm for cartographic rendering

ABSTRACT

Although the extrusion of 1D polylines into a 2D polygon and the tessellation of the polygon into primitives has been performed in the field of computer graphics, the efficient, robust, and high-quality tessellation of thick polylines that supports various cartographic styles for polyline rendering remains a practical challenge. We examined and compared existing vertex-, segment-, and polygon-based algorithms, and present a chain-based tessellation algorithm for cartographic rendering: points in the polyline are classified into abrupt and smooth points according to their point spacing, angle and thickness. The polylines are then divided into abrupt and smooth chains by clustering points that are adjacent and of the same type. An optimal algorithm is also presented to continuously tessellate the smooth chains into minimum geometric primitives and efficiently tessellate the abrupt chains into geometric primitives. We implemented the proposed algorithm and present the results of robustness, efficiency, quality, and cartographic styling tests conducted on real-world polylines. The results indicate that this approach has substantial advantages when considering all four requirements (robustness, efficiency, quality, and the support for various cartographic styles).     

基于GIS的防洪抗旱符号库制作关键技术研究

地图符号制作是数字地图中的一项关键技术,符号制作的好坏直接关系到成图的效果。本文针对符号设计的基本思想、基本原则问题,分析了国内外热门的GIS软件制作符号的优缺点,以防洪抗旱符号库的设计为例分析了点、线、面等二维符号的制作方法与流程以及一些复杂符号的设计技巧,在Super Map中建立了一套较完整、符合标准的防洪抗旱符号库,为制作防洪抗旱的专题图奠定了基础。     

基于·NET的MapXtreme2004矢量地图符号扩展

MapInfo软件是应用十分广泛的主流GIS软件之一,MapXtreme2004是MapInfo公司最新推出的面向网络地理信息发布的优秀组件。但是MapXtreme2004组件本身符号库功能相对薄弱,且矢量符号库的扩展比较困难,从而在一定程度上限制了其应用。对此,本文提出了一种基于.NET的MapXtreme2004矢量地图符号扩展新思路,即算法绘制、图元合并以及图层存储相结合的方法,详细讨论了该方法的关键技术点、实现思路和步骤,给出了实际应用效果示例。     

基础电子地图符号设计的研究与实践

本文在分析基础电子地图符号设计存在问题的基础上,考虑影响电子地图符号设计的因素,运用视觉感受论和符号论等提出基础电子地图符号的设计原则,探讨了基础电子地图符号类型和视觉变量的设计方法。并在MGISⅡ系统中进行了实验和应用,制作出了基于不同显示模式的大中比例尺和中小比例尺两套符号体系表,取得了较为满意的效果。     

山东龙口大磨曲家金矿地质及地球物理地球化学特征

山东龙口市大磨曲家金矿区位于沂沭断裂带东侧,招平成矿带北端,玲珑金矿田东风矿床北东段。区内控矿赋矿构造为NE向断裂带及派生、伴生次级断裂,两组或多组断裂构造的叠加交汇处是金成矿的最有利部位。石英脉型或蚀变岩型金矿床在含矿带上出现次级高阻的石英脉或者次级高阻的硅化带及绢英岩化带,而次级高阻、高极化率局部异常是该区矿脉异常的基本特征。通过对该区地质暨地球物理、地球化学特征的分析,建立了找矿标志。     

如何利用煤线及标志层在断层带找煤

滕北煤田金达煤矿矿井沿煤巷道施工过程中遇到断层,煤层被切断;通过现场观察,利用断层带充填的煤线、地层标志层、标志层层间距及矿井煤系地层柱状图,判断断失煤的方向和断层落差,成功地找到煤层。     

An efficient method for rendering linear symbols on 3D terrain using a shader language

With the extensive application of virtual geographic environments and the rapid development of 3D visualization analysis, the rendering of complex vector lines has attracted significant attention. Although there are many rendering algorithms in 3D geographic information system (GIS), they are not sufficiently flexible to meet the requirements for rendering linear symbols composed of diverse colors and shapes. However, the interactive rendering of a scene and the accuracy of the symbols are important components for large-scale, complex vector lines. In this paper, we propose a graphics processing unit (GPU)-accelerated algorithm for rendering linear symbols on 3D terrain. Symbol rendering is embedded within the terrain-rendering process, and vector lines are encoded in a 3D texture and then transferred to the GPU. A set of visual properties are used to enrich the expression of symbols with the help of geometric operations in the fragment shader. A series of experiments demonstrate that the proposed method can be utilized for drawing various pixel-exact linear symbols and can achieve real-time rendering efficiency.     

几种特殊多边形的点符填充

多边形点符自动填充是数字地图制图、电子地图制作和 GIS中不可缺少的功能。文中总结了多边形点符填充过程中几种特殊情况的自动判别与处理 ,在此基础上提出了改进的自动点符填充的方法和步骤