Cesium当前层级/缩放级别

// 获取当前层级
      function heightToZoom(height){
                  var A = 40487.57;
                  var B = 0.00007096758;
                  var C = 91610.74;
                  var D = -40467.74;
                  return Math.round(D+(A-D)/(1+Math.pow(height/C, B)));
              }
              var height = Math.ceil(viewer.camera.positionCartographic.height);
              var zoom = heightToZoom(height);
              console.log(zoom,'zoom');