三味中国, china3view

4月13日消息，据Google与开放地理空间联盟的双方确认，KML将成为OGC标准，OGC将会负责维护及扩展KML格式。用Google的话来说，那便是KML成为了地理信息的国际标准，就像像互联网上的HTML标准那样。 以后所创建的KML文件，将可以被更多产品支持，而Google则当然也更乐于看到自己的标准被全球推行。你可以通过Google的高级搜索，指定搜索KML格式文件，以获得互联网上丰富的KML文件资源。

KML是Google Earth/Maps最先支持的一种基于XML语法和文件格式的文件，用于描述和保存各种类型的地理信息。KML还有一种压缩后的格式KMZ，同样也被 Google地图产品支持。你可以用Google Earth导出KML文件，然后用Google Maps打开。

其实，早在最开始接触KML的时候，就觉得这个东西可能会成为国际标准， 只是没想到会这么迅速。这也意味着Google Earth和Google Map更加向GIS 靠拢，GIS必然会迎来一个更加绚烂的市场。

官方地址见： http://www.opengeospatial.org/standards/kml
 
Google submitted KML (formerly Keyhole Markup Language) to the Open Geospatial Consortium (OGC) to be evolved within the OGC consensus process with the following goal: KML Version 2.2 will be an adopted OGC implementation standard. Future versions may be harmonized with relevant OGC standards that comprise the OGC standards baseline. There are four objectives for this standards work:

    * That there be one international standard language for expressing geographic annotation and visualization on existing or future web-based online and mobile maps (2d) and earth browsers (3d).
    * That KML be aligned with international best practices and standards, thereby enabling greater uptake and interoperability of earth browser implementations.
    * That the OGC and Google will work collaboratively to insure that the KML implementer community is properly engaged in the process and that the KML community is kept informed of progress and issues.
    * That the OGC process will be used to insure proper life-cycle management of the KML Standard, including such issues as backwards compatibility.

The OGC has developed a broad Standards Baseline. Google and the OGC believe that having KML fit within that family will encourage broader implementation and greater interoperability and sharing of earth browser content and context.

KML is an XML language focused on geographic visualization, including annotation of maps and images. Geographic visualization includes not only the presentation of graphical data on the globe, but also the control of the user's navigation in the sense of where to go and where to look.

From this perspective, KML is complementary to most of the key existing OGC standards including GML (Geography Markup Language), WFS (Web Feature Service) and WMS (Web Map Service). Currently, KML 2.2 utilizes certain geometry elements derived from GML 2.1.2. These elements include point, line string, linear ring, and polygon.

The OGC and Google have agreed that there can be additional harmonization of KML with GML (e.g. to use the same geometry representation) in the future. The Mass Market Geo Working Group (MMWG) in the OGC will establish such additional harmonization activities. OGC specifications such as Context and Styled Layer Descriptor (SLD) may be considered.