谁知道在地图上任意位置点击获得的2维坐标如何转换成经纬度

movement.position 转换为空间坐标：

var cartesian = viewer.camera.pickEllipsoid(new Cesium.Cartesian2(e.clientX, e.clientY), ellipsoid);
            if (cartesian) {
                var cartographic = ellipsoid.cartesianToCartographic(cartesian);
                var plon = Cesium.Math.toDegrees(cartographic.longitude);
                var plat = Cesium.Math.toDegrees(cartographic.latitude);
                var slon = lon - plon;
                var slat = lat - plat;
                console.log(`Click point coordinate: (${plon.toFixed(10)}, ${plat.toFixed(10)}) - (${slon.toFixed(10)}, ${slat.toFixed(10)})`);
            }