Google Earth Engine（GEE）显示影像可用数量

今天分享一下如何在GEE中计算整年影像的可用数量。

在阅读文献的过程中，发现在使用GEE处理影像时，都会说明某年到某年有多少景影像，处理了多少景。

我也想知道在自己的研究区里有多少景可用的影像

以宁夏为例

GEE代码如下：

var roi = ee.FeatureCollection("users/guaicai666666/Ningxia");
var l8_sr = ee.ImageCollection("LANDSAT/LC08/C01/T1_SR")
.filter(ee.Filter.lt('CLOUD_COVER',5))
  var Landsat8 = {
      scaleImage: function(image) {
      var time_start = image.get("system:time_start");
     image = image.select(["B2","B3","B4","B5","B6","B7"]);
      image = image.divide(10000);
      image = image.set("system:time_start", time_start)
      return image;
    },
    getL8SRCollection : function(startDate, endDate, roi) {
      var dataset = l8_sr.filterDate(startDate, endDate)
                        .filterBounds(roi)
                        .map(Landsat8.scaleImage)
      return dataset;
    }
  };
  //生成逐年
function processYearImage(year, region,data_list) {
  var startDate = ee.Date.fromYMD(year, 1, 1);
  var endDate = ee.Date.fromYMD(year+1, 1, 1);
  var l8 = Landsat8.getL8SRCollection(startDate, endDate, region);
  var Imgs = l8
  var imgSize = Imgs.size();
  print("可用影像"+year,imgSize);
  var imgCount= Imgs.select("B2").map(function(img){
  return img.multiply(0).add(1).toInt();
  }).sum().clip(roi);
  var visParam = {
   min: 10,
   max: 40,
   palette: 'FFFFFF, CE7E45, DF923D, F1B555, FCD163, 99B718, 74A901, 66A000, 529400,' +
   '3E8601, 207401, 056201, 004C00, 023B01, 012E01, 011D01, 011301'
  };
  Map.addLayer(imgCount,visParam,"imgCount"+year);
  var temp_feature=ee.Feature(null,null);
  temp_feature = temp_feature.set('year', year);
  temp_feature = temp_feature.set('imgSize', imgSize);
  data_list.push(temp_feature)
  }
  //循环导出所有影像可用图
function main() {
    //开始年份和结束年份
  var startYear =2013;
  var endYear = 2021;
  var data_list=[]
  for (var year=startYear; year<=endYear; year++) {
    processYearImage(year, roi,data_list);
  }
  var featureCollection = ee.FeatureCollection(data_list);
   //导出谷歌云盘
  Export.table.toDrive({
    collection: featureCollection,
    description: 'imgsize',
    fileFormat: 'CSV'
  });
  print(data_list)
  }
main();

计算结果：

感谢关注，欢迎转发！

声明：仅供学习使用！

GEE demo：

https://code.earthengine.google.com/cc3957763fa39df2acfbaac791357e2f

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