Google 地球 KML 高度模式答案

【问题标题】：Google Earth KML altitude modesGoogle 地球 KML 高度模式
【发布时间】：2014-11-22 14:20:33
【问题描述】：

我对 google earth 的 kml 文件有疑问。当我使用高度模式 clampToGround 时，它完全符合我的预期，它很好地跟随地面。

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom"    xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2">
    <Document>
        <name>pm1kml</name>
        <Style id="poly">
            <LineStyle>
                <color>a000ff00</color>
            </LineStyle>
            <PolyStyle>
                <color>a000ff00</color>
        </PolyStyle>
    </Style>
    <Placemark>
        <styleUrl>#poly</styleUrl>
        <Polygon>
            <extrude>0</extrude>
            <tessellate>0</tessellate>
            <altitudeMode>clampToGround</altitudeMode>
            <outerBoundaryIs>
                <LinearRing>
                    <coordinates>-5.255885800498265,36.11513548688032,123 -5.257614986927059,36.097578762436825,123 -5.257614986927059,36.097578762436825,123 -5.262736094548725,36.08069673306777,123 -5.262736094548725,36.08069673306777,123 -5.27105232206931,36.06513816569425,123 -5.27105232206931,36.06513816569425,123 -5.282244081528993,36.051500967335095,123 -5.282244081528993,36.051500967335095,123 -5.29588127988815,36.04030920787541,123 -5.29588127988815,36.04030920787541,123 -5.311439847261665,36.03199298035483,123 -5.311439847261665,36.03199298035483,123 -5.3283218766307225,36.02687187273316,123 -5.3283218766307225,36.02687187273316,123 -5.345878601074219,36.02514268630436,123 -5.345878601074219,36.02514268630436,123 -5.363435325517715,36.02687187273316,123 -5.363435325517715,36.02687187273316,123 -5.380317354886772,36.03199298035483,123 -5.380317354886772,36.03199298035483,123 -5.395875922260288,36.04030920787541,123 -5.395875922260288,36.04030920787541,123 -5.409513120619445,36.051500967335095,123 -5.409513120619445,36.051500967335095,123 -5.4207048800791275,36.06513816569425,123 -5.4207048800791275,36.06513816569425,123 -5.429021107599713,36.08069673306777,123 -5.429021107599713,36.08069673306777,123 -5.434142215221378,36.097578762436825,123 -5.434142215221378,36.097578762436825,123 -5.435871401650172,36.11513548688032,123 -5.435871401650172,36.11513548688032,123 -5.434142215221378,36.132692211323814,123 -5.434142215221378,36.132692211323814,123 -5.429021107599713,36.14957424069287,123 -5.429021107599713,36.14957424069287,123 -5.4207048800791275,36.16513280806639,123 -5.4207048800791275,36.16513280806639,123 -5.409513120619445,36.178770006425545,123 -5.409513120619445,36.178770006425545,123 -5.395875922260288,36.18996176588523,123 -5.395875922260288,36.18996176588523,123 -5.380317354886771,36.19827799340581,123 -5.380317354886771,36.19827799340581,123 -5.363435325517715,36.20339910102748,123 -5.363435325517715,36.20339910102748,123 -5.345878601074219,36.205128287456276,123 -5.345878601074219,36.205128287456276,123 -5.3283218766307225,36.20339910102748,123 -5.3283218766307225,36.20339910102748,123 -5.311439847261665,36.19827799340581,123 -5.311439847261665,36.19827799340581,123 -5.29588127988815,36.18996176588523,123 -5.29588127988815,36.18996176588523,123 -5.282244081528993,36.178770006425545,123 -5.282244081528993,36.178770006425545,123 -5.27105232206931,36.16513280806639,123 -5.27105232206931,36.16513280806639,123 -5.262736094548725,36.14957424069287,123 -5.262736094548725,36.14957424069287,123 -5.257614986927059,36.132692211323814,123 -5.257614986927059,36.132692211323814,123 -5.255885800498265,36.11513548688032,123 -5.255885800498265,36.11513548688032,123 -5.255885800498265,36.11513548688032,123  </coordinates>
                </LinearRing>
            </outerBoundaryIs>
        </Polygon>
    </Placemark>
</Document>

但是，当我使用relativeToGround 时，只有外部顶点跟随地面。在圆圈的中间，岩石在绿色区域上方，而不是在其下方 123 米处。
图片：http://nl.tinypic.com/r/2vcsvq1/8

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom"    xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2">
    <Document>
        <name>pm1kml</name>
        <Style id="poly">
            <LineStyle>
                <color>a000ff00</color>
            </LineStyle>
            <PolyStyle>
                <color>a000ff00</color>
        </PolyStyle>
    </Style>
    <Placemark>
        <styleUrl>#poly</styleUrl>
        <Polygon>
            <extrude>0</extrude>
            <tessellate>0</tessellate>
            <altitudeMode>relativeToGround</altitudeMode>
            <outerBoundaryIs>
                <LinearRing>
                    <coordinates>-5.255885800498265,36.11513548688032,123 -5.257614986927059,36.097578762436825,123 -5.257614986927059,36.097578762436825,123 -5.262736094548725,36.08069673306777,123 -5.262736094548725,36.08069673306777,123 -5.27105232206931,36.06513816569425,123 -5.27105232206931,36.06513816569425,123 -5.282244081528993,36.051500967335095,123 -5.282244081528993,36.051500967335095,123 -5.29588127988815,36.04030920787541,123 -5.29588127988815,36.04030920787541,123 -5.311439847261665,36.03199298035483,123 -5.311439847261665,36.03199298035483,123 -5.3283218766307225,36.02687187273316,123 -5.3283218766307225,36.02687187273316,123 -5.345878601074219,36.02514268630436,123 -5.345878601074219,36.02514268630436,123 -5.363435325517715,36.02687187273316,123 -5.363435325517715,36.02687187273316,123 -5.380317354886772,36.03199298035483,123 -5.380317354886772,36.03199298035483,123 -5.395875922260288,36.04030920787541,123 -5.395875922260288,36.04030920787541,123 -5.409513120619445,36.051500967335095,123 -5.409513120619445,36.051500967335095,123 -5.4207048800791275,36.06513816569425,123 -5.4207048800791275,36.06513816569425,123 -5.429021107599713,36.08069673306777,123 -5.429021107599713,36.08069673306777,123 -5.434142215221378,36.097578762436825,123 -5.434142215221378,36.097578762436825,123 -5.435871401650172,36.11513548688032,123 -5.435871401650172,36.11513548688032,123 -5.434142215221378,36.132692211323814,123 -5.434142215221378,36.132692211323814,123 -5.429021107599713,36.14957424069287,123 -5.429021107599713,36.14957424069287,123 -5.4207048800791275,36.16513280806639,123 -5.4207048800791275,36.16513280806639,123 -5.409513120619445,36.178770006425545,123 -5.409513120619445,36.178770006425545,123 -5.395875922260288,36.18996176588523,123 -5.395875922260288,36.18996176588523,123 -5.380317354886771,36.19827799340581,123 -5.380317354886771,36.19827799340581,123 -5.363435325517715,36.20339910102748,123 -5.363435325517715,36.20339910102748,123 -5.345878601074219,36.205128287456276,123 -5.345878601074219,36.205128287456276,123 -5.3283218766307225,36.20339910102748,123 -5.3283218766307225,36.20339910102748,123 -5.311439847261665,36.19827799340581,123 -5.311439847261665,36.19827799340581,123 -5.29588127988815,36.18996176588523,123 -5.29588127988815,36.18996176588523,123 -5.282244081528993,36.178770006425545,123 -5.282244081528993,36.178770006425545,123 -5.27105232206931,36.16513280806639,123 -5.27105232206931,36.16513280806639,123 -5.262736094548725,36.14957424069287,123 -5.262736094548725,36.14957424069287,123 -5.257614986927059,36.132692211323814,123 -5.257614986927059,36.132692211323814,123 -5.255885800498265,36.11513548688032,123 -5.255885800498265,36.11513548688032,123 -5.255885800498265,36.11513548688032,123  </coordinates>
                </LinearRing>
            </outerBoundaryIs>
        </Polygon>
    </Placemark>
</Document>

我需要的是来自clampToGround 的多边形提升了 123 米。这可能与谷歌地球的 kml 文件。如果是这样，我该怎么做？
提前致谢！

编辑：它已经被报告为一个问题：https://code.google.com/p/kml-samples/issues/detail?id=432

【问题讨论】：

标签： kml google-earth

【解决方案1】：

KML 规范中定义的clampToGround 和relativeToGround 之间存在明显的行为差异。

clampToGround 根据定义遵循地形，这样如果多边形与地形相交，多边形将包裹山或丘陵的表面。

另一方面，

relativeToGround 创建一个平行于地面的平面，该平面穿过任何山脉和丘陵，如下图所示。 123 米的 relativeToGround 是高于地面而不高于岩石顶部的 123 的地面高程。相对于地面零高程的是这个实例是岩石的底部。

直布罗陀的岩石在山顶大约高出地面 390 米，因此 123 米的相对高度穿过岩石。如果您希望多边形在岩石尖端上方 123 米处，那么您应该使相对高度约为 513 米，这就像在该位置上方低悬的绿色云一样。

或者，如果您想用绿色多边形包裹岩石顶部并且多边形平面升高 123 米（穿过岩石），那么建议您使用 relativeToGround 定义第二个多边形 MultiGeometry（如上面列出的）和一个较小的圆圈，刚好覆盖岩石的尖端，altitudeMode=clampToGround。

<MultiGeometry>
 <Polygon>
  <altitudeMode>relativeToGround</altitudeMode>
  ... use coordinates of original polygon here
 </Polygon>
 <Polygon>
  <altitudeMode>clampToGround</altitudeMode>
  ... use coordinates of smaller polygon here
 </Polygon>
</MultiGeometry>

但是，如果您想要让多边形跟随地形形状的clampToGround 行为，但高于地面，那么您需要在relativeToGround 模式下创建多边形的小网格。

【讨论】：

感谢您的回答，但这并不是我真正想要的。我希望多边形在多边形的每个点都高于地面 123 米，多边形必须跟随地形，但在其上方 123 米的高度。因此，在岩石顶部，多边形的高度为 513 米，而在海面下方，高度仅为 123 米。起初我以为tessellate 会对此有所帮助，但它不会。我可以自己镶嵌多边形，但它会很慢，我需要创建非常小的多边形以使其看起来不错。
Tessellate 仅适用于clampToGround 模式。更新了答案。看看有没有帮助。
如果想要 123 米完全高于岩石尖端的海拔，则将海拔 123 高于尖端，大约为 513。但如果真的想要clampToGround 但高于地面，那么你需要创建一系列123 处的小块或子网格。较小的多边形将相对于岩石下方的地面，而不是海平面。
我真的希望clampToGround 高出地面，我希望我不必创建子网格，但谷歌会用其中一种高度模式为我做到这一点。感谢您的帮助。