cesium定位

要注意两者定位不一样
相机定位会出现偏移

 let alt=that.getHeightByLevel(14)
        //相机定位
        // viewer.camera.flyTo({
        //   destination : Cesium.Cartesian3.fromDegrees(lon,lat,alt),
        //   orientation : {
        //     heading : Cesium.Math.toRadians(0.0),
        //     pitch : Cesium.Math.toRadians(-15.0),//倾斜角度
        //     roll : 0.0
        //   },
        //   // duration:1.5//动画持续时间
        //   complete:()=>{//飞行结束之后执行的方法
        //   }
        // });
        //经纬度定位
        if (that.entity){
          viewer.entities.remove(that.entity);
          that.entity=null;
        }
        that.entity = new Cesium.Entity({
          id : 'flyTmp',
          position : Cesium.Cartesian3.fromDegrees(lon, lat),
          point : {
            pixelSize : 15,
            color : Cesium.Color.RED.withAlpha(0.9),
            outlineColor : Cesium.Color.RED.withAlpha(0.9),
            outlineWidth : 1,
            disableDepthTestDistance: Number.POSITIVE_INFINITY,
            heightReference: Cesium.HeightReference.CLAMP_TO_GROUND,
          }
        });
        viewer.entities.add(that.entity);
        viewer.flyTo(that.entity, {
          offset : {
            heading : Cesium.Math.toRadians(0.0),
            pitch : Cesium.Math.toRadians(-25),
            range : alt
          }
        });