cesium 获取点击点的高程

var picklHandler = new Cesium.ScreenSpaceEventHandler(viewer.scene.canvas);
picklHandler .setInputAction(function (click) {

　　var pick = viewer.camera.getPickRay(click.position);
　　var cartesian = scene.globe.pick(pick, viewer.scene);
　　if (cartesian) {
　　　　var cartographic = Cesium.Cartographic.fromCartesian(cartesian);
　　　　var longitudeString = Cesium.Math.toDegrees(cartographic.longitude);//经度
　　　　var latitudeString = Cesium.Math.toDegrees(cartographic.latitude);//纬度
　　　　var heightString = viewer.scene.globe.getHeight(cartographic);//获取拾取点的高程

　　}

},Cesium.ScreenSpaceEventType.LEFT_CLICK)