Google Earth Engine（GEE）学习笔记1.影像加载去云筛选导出

加载影像

//加载Landsat8
var l8 = ee.ImageCollection("LANDSAT/LC08/C01/T1_SR")
//加载sentinel
var imageCollection = ee.ImageCollection("COPERNICUS/S1_GRD"),
var imageCollection2 = ee.ImageCollection("COPERNICUS/S2"),
var imageCollection3 = ee.ImageCollection("COPERNICUS/S2_SR");

影像去云函数

//Landsat8去云
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); 
} 
//Sentinel去云
var cloudfunction_ST2 = function(image){
  //use add the cloud likelihood band to the image
  var quality = image.select("QA60").unmask();
  //get pixels above the threshold
  var cloud01 = quality.gt(0);
  //create a mask from high likelihood pixels
  var cloudmask = image.mask().and(cloud01.not());
  //mask those pixels from the image
  return image.updateMask(cloudmask);
};

影像筛选显示

//定义时间节点
var startdate = ee.Date.fromYMD(2020,9,1);
var enddate = ee.Date.fromYMD(2020,10,30);
//landsat8
//影像筛选
var l8Imgs  = l8 .filterBounds(roi)
            .filterDate(startdate, enddate)
            .filterMetadata('CLOUD_COVER','less_than',5);
Map.setCenter( 107.753, 34.238, 4);                                                        
Map.addLayer( L8, {bands:'B4,B3,B2', min:0, max:0.2}, 'Original Images' );
//sentinel
//s1为从GEE 数据集导入的Sentinel 1数据
var Sentinel1_VV =  s1.filterBounds(roi)
                    .filterDate(startdate, enddate)
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV'))
                    .select('VV')
                     .median();
​
var Sentinel1_VH =  s1.filterBounds(roi)
                    .filterDate(startdate, enddate)
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation',                       'VH'))
                   
                    .select('VH')
                    .median();
//s2为从GEE 数据集导入的Sentinel 2数据
var Sentinel2 = s2.filterBounds(roi)
                .filterDate(startdate, enddate)
                .map(cloudfunction_ST2)
                 .median();

影像导出

//影像数据集下载
//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(table), 
         description: indexs[i], 
         fileNamePrefix: indexs[i], 
         region: table, 
         scale: 30, 
         crs: "EPSG:4326", 
         maxPixels: 1e13 
       }); 
     } 
   }); 
 } 
 exportImageCollection(l8Imgs); 

标签：Engine,startdate,Google,enddate,ee,image,GEE,var,影像
来源： https://blog.csdn.net/ZZSOGA/article/details/120403728