After the superposition of elevation, drawing the line to a certain level will produce a certain lev

CesiumJS
1

var imageprovider = new WMTSImageryProvider('http://www.google.cn/maps/vt?lyrs=y@198&gl=cn&x={x}&y={y}&z={z}', true, { alpha: 1 });//Load Google Image

        var localterrainprovider = new Cesium.CesiumTerrainProvider({ url: ipConfig + ':2001/dem' });//Stack height
        
        var viewer = new Cesium.Viewer('cesiumContainer', {
                imageryProvider: imageprovider,
                terrainProvider: localterrainprovider,
                baseLayerPicker: false,
                timeline: false,
                sceneModePicker: true,
                geocoder: false,
                scene3DOnly: false,
                animation: false
            });

//Drawing line code
var rgba = [72, 61, 139, 255];
                
                var czmls = [
                  {
                    "id" : "document",
                    "name" : "CZML Geometries: Polyline",
                    "version" : "1.0"
                  },
                  {
                    "id" : "blueLine",
                    "name" : "Glowing blue line on the surface",
                    "polyline" : {
                      "positions" : {
                        "cartographicDegrees" : Arrays
                      },
                      "material" : {
                        "polylineGlow" : {
                          "color" : {
                            "rgba" : rgba,
                            "glowPower" : 0
                          }
                        }
                      },
                      "width" : 15
                    }
                  },
                ];
                var dataSource = Cesium.CzmlDataSource.load(czmls);
                viewer.dataSources.add(dataSource);
                viewer.zoomTo(dataSource);