cesium四至坐标如何转换成经纬度

所谓四至坐标，也就是东西南北各有一个值，如何转换成经纬度坐标？

                let coor = obj.rectangle.coordinates._value;

                const northwest = Cesium.Rectangle.northwest(coor);
                const southwest = Cesium.Rectangle.southwest(coor);
                const northeast = Cesium.Rectangle.northeast(coor);
                const southeast = Cesium.Rectangle.southeast(coor);


                const leftTop = [Cesium.Math.toDegrees(northwest.longitude),Cesium.Math.toDegrees(northwest.latitude)]
                const leftBottom = [Cesium.Math.toDegrees(southwest.longitude),Cesium.Math.toDegrees(southwest.latitude)]
                
                const rightTop = [Cesium.Math.toDegrees(northeast.longitude),Cesium.Math.toDegrees(northeast.latitude)]
                
                const rightBottom = [Cesium.Math.toDegrees(southeast.longitude),Cesium.Math.toDegrees(southeast.latitude)]
            
                newObj = { rectangles:[leftTop.join(';'),leftBottom.join(';'),rightTop.join(';'),rightBottom.join(';')] };