show station dot in smaller scale

      console.log("NKDH1 route layer added.");

      // 添加站点、建筑和校门图层

      this.addSymbolLayer('stations', this.allStationsGeoJSON, 'bus-station-icon', 0.075, [0, 1.25]);

      // station 语义缩放

      if (!this.map.getSource('stations-source')) {

        this.map.addSource('stations-source', {

          type: 'geojson',

          data: this.allStationsGeoJSON

        });

      }

      // (B) 添加圆点图层

      this.map.addLayer({

        'id': 'stations-dots',

        'type': 'circle',

        'source': 'stations-source',

        'maxzoom': 16.5,

        'paint': {

          'circle-radius': 4,

          'circle-color': '#1fa252',

          'circle-stroke-width': 1.5,

          'circle-stroke-color': '#ffffff'

        }

      });

      // (C) 添加图标图层

      this.map.addLayer({

        'id': 'stations-icons',

        'type': 'symbol',

        'source': 'stations-source',

        'minzoom': 16.5,

        'layout': {

          'icon-image': 'bus-station-icon',

          'icon-size': 0.075,

          'icon-anchor': 'bottom',

          'icon-offset': [0, 0],

          'text-field': ['get', 'name'],

          'text-size': 12,

          'text-offset': [0, 1.25],

          'text-anchor': 'top'

        },

        'paint': {

          'text-color': '#333',

          'text-halo-color': '#fff',

          'text-halo-width': 2

        }

      });

      // this.addSymbolLayer('stations', this.allStationsGeoJSON, 'bus-station-icon', 0.075, [0, 1.25]);

      this.addSymbolLayer('buildings', this.bldgGeoJSON, 'bldg-icon', 0.02, [0, 0.3], 11);

      this.addSymbolLayer('gates', this.gateGeoJSON, 'gate-icon', 0.05, [0, 0.6]);

    },