arcgis js统计FeatureLayer的椭球面积、平面面积

1、导入依赖

import FeatureLayer from '@arcgis/core/layers/FeatureLayer'
import { geodesicArea, planarArea, simplify } from '@arcgis/core/geometry/geometryEngine';
import { project, load as projectionLoad } from '@arcgis/core/geometry/projection'

2、初始化project

onMounted(() => {
  // 第一步：加载投影引擎
  projectionLoad()
})

3、计算椭球面积、平面面积

const calculateFeatureLayer = async (featureLayer: FeatureLayer) => {

  const query = featureLayer.createQuery()
  query.where = '1 = 1'
  const result = await featureLayer.queryFeatures(query)

  // 总面积统计
  let totalGeoArea = 0;
  let totalPlanarArea = 0;

  for (const feature of result.features) {
    if (feature.geometry.type === 'polygon') {
      let geometry = feature.geometry

      // 坐标系转换
      if (geometry.spatialReference.wkid !== 4326) {
        geometry = await project(geometry, { wkid: 4326 }) as any
      }

      // 简化多边形
      const simplifiedPolygon = simplify(geometry)

      // 椭球面积
      const geoArea = geodesicArea(simplifiedPolygon, "square-kilometers")
      totalGeoArea += geoArea

      // 平面面积
      const projectedGeometry = await project(simplifiedPolygon, { wkid: 3857 }) as any
      const planarAreaResult = planarArea(projectedGeometry, "square-kilometers")
      totalPlanarArea += planarAreaResult
    }
  }

  console.log("椭球面积(平方千米):", totalGeoArea)
  console.log("毛面积(平方千米):", totalPlanarArea)

}