利用VML和SVG绘制军标箭头符号的算法实现  

Algorithm of military arrow symbol plotting based on VML and SVG

作　　者：刘丹 李刚 田银枝 曹红杰 

机构地区：[1]北京合众思壮导航技术有限公司,北京100015 [2]北京超图信息技术有限公司,北京100015

出　　处：《测绘科学》2014年第4期115-118,130,共5页Science of Surveying and Mapping

基　　金：科技部863计划(2012AA12A201)

摘　　要：VML和SVG在很大程度上解决了WebGIS的图形绘制问题,特别是对军用标绘箭头这类复杂图形的绘制效率和效果的提升更加明显。本文提出的绘制模式基于XML标准,采用自由中心线取得控制点算法实现,由控制点计算获得贝赛尔曲线,再由贝赛尔曲线按照一定规则组合连接完成军标箭头的绘制,通过VML和SVG提供的相关颜色属性和渲染规则对生成的军标箭头进行渲染,运用仿射变换原理解决箭头符号的编辑问题。该算法克服了输入控制点生成军标箭头算法的操作复杂性,基于XML开源方便了跨平台移植,提高了可复用性。利用VML和SVG绘制图形格式小,提高了浏览速度,使得WebGIS系统性能有一定提升。VML and SVG largely solve graphics rendering problems in WebGIS, especially for enhancing the efficiency and the effectiveness of drawing the complex graphics of military plotting arrows. In this paper, the drawing mode based on the XML standard was proposed. The algorithm of control points was realized by using free center line. The Bezier Curve was obtained through the control point calculation. According to certain rules of combination connection, the Bezier Curve completed the drawing of military arrow symbols. Military arrow symbols were rendered by the color attribute and rendering rules provided by VML and SVG. The theory of affine transformation was used to solve the editing problem of arrow symbols. The algorithm could overcome the operational complexity of the algorithm using input control points to generate military arrow symbols, and the cross-platform ability of XML would improve the system＇s reusability. Moreover, the drawing format based on VML and SVG would be small, which improves the browsing speed, and enhances the performance of WebGIS svstem.

关 键 词：VML SVG 控制点 贝赛尔曲线 仿射变换 

分 类 号：P208[天文地球—地图制图学与地理信息工程] TP311[天文地球—测绘科学与技术]