在GEE中提取多个点的带值

Question

我有一个关于从GEE导出数据的问题。我是编码和GEE的新手。我想要实现的是导出使用Fusion Table上传的点a的像素带数据。 GEE是否可以以表格的形式导出那些点的带数据？

我的代码到目前为止：https://code.earthengine.google.com/8a764b5d22a9f7108152fce1acc1fe16

代码：

// Load a FeatureCollection from a Fusion Table
var CRuHM_small_data = ee.FeatureCollection('ft:1ocXhbAqP_NbA0iE7tivKgKCfTFGseNdibklZj0NX');

// Print and display the FeatureCollection.
Map.addLayer(CRuHM_small_data,{},'CRuHM_small_data');
print(CRuHM_small_data);

//Navigate to area of interest
Map.setCenter(17.3834, -0.8929, 8);

// Select a specific Sentinel-2 image from the archive
var sent2a = ee.Image("COPERNICUS/S2/20170801T090021_20170801T091620_T33MYV");

// Add RGB composite to map, for water/land
Map.addLayer(sent2a,{bands:['B8','B11','B4'], min:0, max:3000}, "water/land");

However, the next step is more complicated for me. 
I was trying this code, but something is missing:(

//exporting band data to table
//Export.table.toDrive(collection, description, folder, 
//fileNamePrefix, fileFormat, selectors),

Export.table.toDrive({
  collection: CRuHM_small_Data,
  description: "CRuHM_small_Data",
  folder: "GEE",
  fileNamePrefix: "Table",
  fileFormat: "CSV",
  selectors: ["ID", "B3", "B2"]
  });

Answer 1

所以你想要的是一个名为samplesRegions的函数，用于ee.Image对象。

在你的情况下，它会是这样的

var sampledData = sent2a.sampleRegions({
  collection:CRuHM_small_data,
  scale:10
});

Export.table.toDrive({
  collection: sampledData,
  description: "CRuHM_small_Data",
  folder: "GEE",
  fileNamePrefix: "Table",
  fileFormat: "CSV",
  selectors: ["ID", "B3", "B2"]
});

由于您需要关于点的波段信息，您必须使用点对波段进行采样，然后导出采样点。

此外，由于您似乎只想从B2和B3导出信息，因此在采样前对图像进行选择会更好。

在您的sampleRegions应该做的事情之前的某个地方。

sent2a = sent2a.select(['B2', 'B3']);