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FeatureCollection的批量下载

https://zhuanlan.zhihu.com/p/80340644

var l8 = ee.ImageCollection("LANDSAT/LC08/C01/T1_SR"); 
var roi = /* color: #d63000 */ee.Geometry.Polygon( 
        [[[115.64960937499995, 39.112756306811285], 
          [116.28681640624995, 39.163883889810315], 
          [116.21540527343745, 39.58850167846649], 
          [115.70454101562495, 39.6054326422912]]]); 
Map.centerObject(roi, 8); 

function rmL8Cloud(image) { 
  var cloudShadowBitMask = (1 << 3); 
  var cloudsBitMask = (1 << 5); 
  var qa = image.select('pixel_qa'); 
  var mask = qa.bitwiseAnd(cloudShadowBitMask).eq(0) 
                 .and(qa.bitwiseAnd(cloudsBitMask).eq(0)); 
  return image.updateMask(mask); 
} 

var l8Imgs = l8.filterBounds(roi) 
               .filterDate("2018-1-1", "2018-3-1") 
               .map(rmL8Cloud); 
print("l8Imgs", l8Imgs); 
Map.addLayer(l8Imgs, {min:0, max:3000, bands:["B4","B3","B2"]}, "l8Imgs"); 
Map.addLayer(roi, {color: "red"}, "roi"); 


//影像集合导出方法 
function exportImageCollection(imgCol) { 
  var indexList = imgCol.reduceColumns(ee.Reducer.toList(), ["system:index"]) 
                        .get("list"); 
  indexList.evaluate(function(indexs) { 
    for (var i=0; i<indexs.length; i++) { 
      var image = imgCol.filter(ee.Filter.eq("system:index", indexs[i])).first(); 
      image = image.toInt16(); 
      Export.image.toDrive({ 
        image: image.clip(roi), 
        description: indexs[i], 
        fileNamePrefix: indexs[i], 
        region: roi, 
        scale: 30, 
        crs: "EPSG:4326", 
        maxPixels: 1e13 
      }); 
    } 
  }); 
} 


exportImageCollection(l8Imgs); 

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