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可惜webgis中svg的内容太少，作为未来可能的主流，应该多关注些

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更多发布于：2004-09-01 09:18

svg作为微软极力推荐的矢量图的描述格式，有着不可估量的前景，而且在解决目前webgis的一些图形表现上也有着很好的补充和扩展作用。只可惜本版关于此信息的内容实在太少了，希望能有更多好的信息，也欢迎大家交流。

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gis 管理员注册日期2003-07-16 发帖数15945 QQ554730525 铜币25337枚威望15352点贡献值0点银元0个加关注写私信	1楼^# 发布于：2004-09-01 11:16 是啊。看过一些svg的例子，功能的确很强大，希望能看到更多的应用
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发布于：2004-09-02 09:10

关注的人比较多，呵呵。
真正使用的人比较少；首先得有项目支撑，然后得有领导支持（长时间研究）。
SVG的技术支持也不怎么样，现在也是处于初始阶段。
另外：SVG的应用如果不能和当前的主流GIS平台结合的话，可能推广起来比较困难，毕竟现在的GIS市场已经如火如荼，而推广只靠Micro显然不行，必须和GIS厂家联手，合作。那又是什么时候。

[此贴子已经被作者于2004-9-2 9:14:17编辑过]

| －－－－－－－－－－－－－ | 白云悠悠矶头月涌千骏过，往事渺渺江上风情一燕来。 | －－－－－－－－－－－－－ | [img]http://www.gisempire.com/bbs/showimg.asp?BoardID=3&filename=2004-9/200491972356282.gif[/img]

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发布于：2004-09-02 09:17

<DIV align=center><TABLE #ffffd0; WIDTH: 100%; mso-cellspacing: 1.5pt; mso-padding-alt: 7.5pt 7.5pt 7.5pt 7.5pt" cellPadding=0 width="100%" bgColor=#ffffd0 border=0><TR><TD #ece9d8; PADDING-RIGHT: 7.5pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 7.5pt; PADDING-BOTTOM: 7.5pt; BORDER-LEFT: #ece9d8; PADDING-TOP: 7.5pt; BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent" vAlign=top>Scalable Vector Graphics (SVG) for Web MappingReport in Cartographic Visualisation course at University of GavleRobert Siirilä 2000-11-06Internet is build on open standards. There are standards for transfering data, for text documents, for requests, for images etc. To recently there was no standard for vector graphics. Web site creators have to make complicated detours to make dynamic graphics. Today we have this standard: Scalable Vector Graphics (SVG). This paper gives a brief introduction to SVG, compares it with the traditional methods of map rendering. The paper further shows the some features of SVG, example implementations and discuss how to create vector maps dynamically from the server. Short cut to the examples: <a>Animated SVG</A> ¦ <a>Interactive SVG</A> ¦ <a>Facility Information</A>IntroductionSVG is an open-standard vector graphics language describing 2D graphics with HTML-like markup text. SVG allows for three types of graphic objects: vector graphic shapes, images and text. Graphical objects can be grouped, styled, transformed and composited into previously rendered objects. The feature set includes nested transformations, clipping paths, alpha masks, filter effects and template objects. SVG can be interactive and dynamic. Animations can be defined and triggered either by embedding SMIL animation elements or via ECMAscript (Javascript). A sample svg-file. The style-attribute is stylesheet CSS:

 <svg>
 <rect x="10" y="10" width="100" height="100"
 style="fill:rgb(255 255 208) ;stroke: rgb(255 208 0) ; stroke-width: 5"/>
 </svg>

<a>Sample SVG</A> SVG compared to other map rendering approachesThree main approaches for render graphics on the web: Raster imageGIF, TIF, JPG, PNG and other bitmap formats.Images are suitable for fuzzy objects, like a fuzzy car driving very fast in a map of Goteborg. <v:shapetype><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path connecttype="rect" gradientshapeok="t" extrusionok="f"></v:path><lock aspectratio="t" v:ext="edit"></lock></v:shapetype><v:shape><v:imagedata></v:imagedata><lock v:ext="edit" cropping="t"></lock><w:wrap type="square"></w:wrap></v:shape>Dynamic maps are created with a map engine on the server. A new image must be sended to the client when the user zooms or pans the map. The fact that images doesn't need plug-ins or applets is an advantage over vector graphics. Examples of commercial map engines with this approach: MapInfo Xtreme, AutoDesk MapGuide Binary vector graphicsJava-applets, Macromedia Flash and Adobe PDF.The server streams binary code to a client-side java-applet. The fallbacks with this approach is that a often heavy applet must be downloaded before use. Applets doesn't have the many graphical features of "real" vector formats, applets have a tendency to be slow and full with bugs. A consequense of the complicated and unforgiving nature of Java. Why use programs inside programs when it's not necessary? The binary format is favourable for map owners - no one can steal the maps. Example of commercial map engines with this approach: ESRI ArcIMS Macromedia Flash and Adobe PDF need plug-ins to be rendered. They have both many, but not all, of the graphics features of SVG. But they are proprietary binary formats. To edit these you need to buy their programs. The formats are not standards neither compliant with web standards. An another disadvantage of binary formats, both vector and raster, is that the different parts of the document are not visible for text-searching. They are invisible for search-engines. Text-based vector graphicsMicrosoft's Vector Markup Language (VML), Adobe's Precision Graphics Markup Language (PGML) and SVG. VML and PGML are obsolete today. SVG is a convergence of those two formats. Virtual Reality Modelling Language (VRML) is also capable to render 2D graphics.Some features of SVGScriptingSVG with ECMAScript. This example shows how attributes can be changed with event-handling. In this case the color-attibute and text-data of elements changes depening on the position of the mouse <a>Interactive SVG</A> AnimationSVG with SMIL-animation. SMIL is a XML language for streaming media. This example shows how attributes of elements change with time. The coordinates in this case. The example also shows the graphical difference between vector graphics and raster graphics. The background is a raster image of University of Gavle. The example further shows different painting (gradients) and transparency effects. <a>Animated SVG</A> An Example: Facility InformationThis is an example of a dynamic map. The application shows information about the students living in House 31, which is a part of the Midgardslunden Hall of Residence. The hall is located just behind the Midgard Student Association House in Gavle. This map shows basic dynamical features. When mouse moves over an object the object gets highlighted and information is shown on the attribute table. <a>Facility Information</A>Dynamically created vector mapsHow to extract maps from a spatial database? Which approach is preferable when user needs to collect data from different parts from a spatial database and visualize this collection on the browser? The common approach today is a map engine, combined with a webserver and a databasemanager, that produces a raster map and send it to the user's browser. SVG is a markup format like html. So it would be possible to send SVG text to the browser instead of a raster image. The raster image engine would be unnecessary. XML is also a markup format, so instead of a external database it would be possible to use XML as a database format. So with this approach we need only a web server that understands XML. No raster image engines and database management systems. Easy and simple compared to the common approach. We can look at the XML format as content and SVG as presentation. Now we can use XSLT (eXtended Style Language, Transformation). The XSLT extracts data from the XML database and transforms it to SVG. This could make things easier. We have to make a transformation specification, ie how to visualize different kinds of data. Then we need a dynamically made XSLT from user request to extract data from the XML database. To make dynamic XSLT is a task for the web server. ConclusionTextual vector graphics would make the maps on the web more interactive and simplify the server technology. Simple means fast and more bugfree. The major problem is that this is a new approach in this area. There are not sufficient knowledge and supported software. There are lot of questions and unsolved problems, known and unknown, when moving from a theoretical idea to a real implementation. ReferencesOther standards and open source<a href="http://www.libpng.org/pub/png/png.html" target="_blank" >Portable Network Graphics (PNG) Home Site</A>
<a href="http://www.libpng.org/pub/mng/" target="_blank" >Multiple-Image Network Graphics (MNG)</A>
<a href="http://www.jsworld.com/ecmascript/" target="_blank" >ECMAScript Tutorial</A> (ECMA-262) The only open-standard scripting language for the webSVG Papers<a href="http://www.w3.org/TR/SVG/" target="_blank" >W3C Scalable Vector Graphics (SVG) 1.0 Specification</A>
<a href="http://www.oasis-open.org/cover/svg.html" target="_blank" >Oasis, The XML Cover Pages: W3C SVG</A>
<a href="http://www.w3c.org/" target="_blank" >W3C - World Wide Web Consortium</A> The developer of SVG, XML, XSLT, HTML and moreSVG Software<a href="http://www.sun.com/software/xml/developers/svg/" target="_blank" >Sun's SVG pages</A> Tutorials and software for Dynamic SVG rendering and more
<a href="http://www.adobe.com/svg" target="_blank" >Adobe SVG Zone</A> Tutorials and download Adobe SVG Viewer
<a href="http://www.ionic.be/ionic/svg/" target="_blank" >IONIC SVG Renderer</A>
<a href="http://sis.cmis.csiro.au/svg/" target="_blank" >CSIRO SVG Toolkit</A>SVG Creations<a href="http://www.pinkjuice.com/SVG/" target="_blank" >Pinkjuice</A> With the most extensive collection of links about SVG
<a href="http://www.kevlindev.com/" target="_blank" >KevLinDev</A> SVG and JavaScriptSVG Maps<a href="http://www.carto.net/papers/svg/index_e.html" target="_blank" >cartpapers:svg</A> Andreas Neumann and Andre Winter - The leading svg-map makers. <a href="http://www.student.hig.se/~tp98rsa/index.html" target="_blank" >Home</A> ¦ <a href="http://www.student.hig.se/~tp98rsa/geocollab/authors.html" target="_blank" >People</A> ¦ <a href="http://www.student.hig.se/~tp98rsa/geocollab/projects.html" target="_blank" >Projects</A><DIV class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align=center><HR align=center width="100%" SIZE=2></DIV>© 2000 Robert Siirilä. Last revised 2001-11-10.

<SCRIPT language=JavaScript type=text/javascript>
sw="none";sd="none";ref=""+escape(document.referrer);  </SCRIPT><SCRIPT language=JavaScript1.2 type=text/javascript>sw=screen.width;nav=navigator.appName;sc=(nav!="Netscape")?screen.colorDepth:screen.pixelDepth;  </SCRIPT><SCRIPT language=JavaScript type=text/javascript>function doit(str) {document.writeln(str);}qs="&sw="+sw+"&sc="+sc+"&ref="+ref;url='http://counter49.bravenet.com/index.php?';url += 'id=347629&usernum=4200230388&cpv=1';curl='http://counter49.bravenet.com/counter.php?id=347629&usernum=4200230388';doit('<a href="'+url+'" target="_blank" ><img src="'+curl+qs+'"></a>')  
<script>

| －－－－－－－－－－－－－ | 白云悠悠矶头月涌千骏过，往事渺渺江上风情一燕来。 | －－－－－－－－－－－－－ | [img]http://www.gisempire.com/bbs/showimg.asp?BoardID=3&filename=2004-9/200491972356282.gif[/img]

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zyk7962 路人甲注册日期2003-12-10 发帖数16 QQ 铜币156枚威望0点贡献值0点银元0个加关注写私信	4楼^# 发布于：2004-09-06 11:13 GeoMedia WebMap 5.1b已经开始支持SVG了。
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发布于：2004-09-06 14:42

用SVG技术实现基于Web的GIS：<a href="http://www-900.ibm.com/developerWorks/cn/xml/x-webgis/index.shtml" target="_blank" >http://www-900.ibm.com/developerWorks/cn/xml/x-webgis/index.shtml</A>

| －－－－－－－－－－－－－ | 白云悠悠矶头月涌千骏过，往事渺渺江上风情一燕来。 | －－－－－－－－－－－－－ | [img]http://www.gisempire.com/bbs/showimg.asp?BoardID=3&filename=2004-9/200491972356282.gif[/img]

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hengyu 路人甲注册日期2004-01-08 发帖数65 QQ24637884 铜币406枚威望0点贡献值0点银元0个加关注写私信	6楼^# 发布于：2004-09-07 10:52 <P>楼上的，虽然已经看过这篇文章，但再看看也还是挺好的。顶。。。。</P>
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hengyu 路人甲注册日期2004-01-08 发帖数65 QQ24637884 铜币406枚威望0点贡献值0点银元0个加关注写私信	7楼^# 发布于：2004-09-16 17:38 我想发个关于svg的文档，可是要1M，好像不能直接通过创建新贴发啊：）
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hlf111 路人甲注册日期2004-06-16 发帖数2 QQ 铜币118枚威望0点贡献值0点银元0个加关注写私信	8楼^# 发布于：2004-09-18 22:10 <P>准备用SVG实现WEBGIS,欢迎登录<a href="http://www.websamba.com/hlfskygis" target="_blank" >www.websamba.com/hlfskygis</A>,刚上传一些内容,还有点错误.算是一个雏形吧.共同交流,共同提高.欢迎与我联系:hlf111@163.com .</P>
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huanger001 路人甲注册日期2004-02-19 发帖数28 QQ 铜币258枚威望0点贡献值0点银元0个加关注写私信	9楼^# 发布于：2004-10-03 17:44 <P>我毕业设计做的就是SVG方面的东西，挺喜欢SVG，</P><P>各位高手有空交流！</P><P>QQ：26304314</P>
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可惜webgis中svg的内容太少，作为未来可能的主流，应该多关注些

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