Cesium-经纬度转换笛卡尔坐标系

CZML(百度查阅)字段里的position里坐标系仅支持cartesian（笛卡尔坐标系），一般的地理位置经纬度较为普遍。Cesium提供了转换接口，并且CZML里position字段支持填入常量（详情翻阅API）。

var position = Cesium.Cartesian3.fromDegrees(116.3912822800,39.9074647400);
var czml = [{
    "id" : "document",
    "name" : "Basic CZML billboard and label",
    "version" : "1.0"
}, {
    "id" : "some-unique-id",
    "name" : "AGI",
    "description" : "
Analytical Graphics, Inc. (AGI) founded Cesium.
",
    "billboard" : {
        "image" : "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAACvSURBVDhPrZDRDcMgDAU9GqN0lIzijw6SUbJJygUeNQgSqepJTyHG91LVVpwDdfxM3T9TSl1EXZvDwii471fivK73cBFFQNTT/d2KoGpfGOpSIkhUpgUMxq9DFEsWv4IXhlyCnhBFnZcFEEuYqbiUlNwWgMTdrZ3JbQFoEVG53rd8ztG9aPJMnBUQf/VFraBJeWnLS0RfjbKyLJA8FkT5seDYS1Qwyv8t0B/5C2ZmH2/eTGNNBgMmAAAAAElFTkSuQmCC",
        "scale" : 2.0
    },
    "label" : {
        "fillColor" : {
            "rgba" : [255, 255, 255, 255]
        },
        "font" : "12pt Lucida Console",
        "horizontalOrigin" : "LEFT",
        "pixelOffset" : {
            "cartesian2" : [8, 0]
        },
        "style" : "FILL",
        "text" : "AGI",
        "showBackground" : true,
        "backgroundColor" : {
            "rgba" : [112, 89, 57, 200]
        }
    },
    "position" : {
        "cartesian":[
            position.x, position.y, position.z
        ]
    }
}];

var viewer = new Cesium.Viewer('cesiumContainer');
viewer.dataSources.add(Cesium.CzmlDataSource.load(czml));
console.log(position);

在Viewer中添加一个地面基站，天安门位置（谷歌地球：纬39.9074647400,经116.3912822800）标记一个基站。
经纬度查询：http://www.gpsspg.com/maps.htm

添加至label字段，基站右侧显示文字：

"text" : "AGI"

zoomTo更改视角：

var viewer = new Cesium.Viewer('cesiumContainer');
var dataSourcePromise = Cesium.CzmlDataSource.load(czml);
viewer.dataSources.add(dataSourcePromise);
viewer.zoomTo(dataSourcePromise);

隐藏Cesium-ion的logo：

viewer._cesiumWidget._creditContainer.style.display = "none";