GEE逐点位提取影像数据集栅格值

两个数据集，一个点文件FeatureCollection，另一个Landsat8影像数据ImageCollection，现在遍历点文件中的每一个点，提取这个点位上所有影像的栅格值（波段值），并导出为csv，适用。

代码：

var firstlyr = ee.FeatureCollection("users/points");

var fqshp = ee.FeatureCollection("users/boundary");

function maskL8sr(image) {

  // Bit 0 - Fill

  // Bit 1 - Dilated Cloud

  // Bit 2 - Cirrus

  // Bit 3 - Cloud

  // Bit 4 - Cloud Shadow

  var qaMask = image.select('QA_PIXEL').bitwiseAnd(parseInt('11111', 2)).eq(0);

  var saturationMask = image.select('QA_RADSAT').eq(0);

  // Apply the scaling factors to the appropriate bands.

  var opticalBands = image.select('SR_B.').multiply(0.0000275).add(-0.2);

  var thermalBands = image.select('ST_B.*').multiply(0.00341802).add(149.0);

  // Replace the original bands with the scaled ones and apply the masks.

  return image.addBands(opticalBands, null, true)

      .addBands(thermalBands, null, true)

      .updateMask(qaMask)

      .updateMask(saturationMask);

}

// Map the function over one year of data.

var dataset = ee.ImageCollection('LANDSAT/LC08/C02/T1_L2')

                     .filterDate('2021-01-01', '2021-02-01')

                     .filterBounds(fqshp)

                     .map(maskL8sr);

print('images number:',dataset.size());

print(dataset);

var mapfunc = function(feat) {

  var geom = feat.geometry();

  var addProp = function(img, f) {

    var newf = ee.Feature(f);

    var values = img.reduceRegion({

      reducer:ee.Reducer.first(),

      geometry:geom,

      scale:30,

      maxPixels:1e11});

      var values_array = ee.Algorithms.If(

      values.get('SR_B1'),

      values.toArray(['SR_B1','SR_B2','SR_B3','SR_B4','SR_B5','SR_B6','SR_B7']),

      9999);

      var fields_name = ee.String(img.get('system:index'));

      return ee.Feature(newf.setMulti(ee.Dictionary.fromLists(ee.List([fields_name]),ee.List([values_array]))));

  };

  var newfeat = ee.Feature(dataset.iterate(addProp, feat));

  return newfeat;

};

var newft = firstlyr.map(mapfunc);

Export.table.toDrive({

  collection: newft,

  description: 'newft',

  fileFormat:'CSV',

  folder:'newft',

  fileNamePrefix:'newft'});

print('done!');

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