{"id":181,"date":"2022-06-19T19:43:00","date_gmt":"2022-06-19T11:43:00","guid":{"rendered":"http:\/\/47.107.115.238\/?p=181"},"modified":"2024-09-15T15:38:52","modified_gmt":"2024-09-15T07:38:52","slug":"gee","status":"publish","type":"post","link":"https:\/\/lxylp.com\/?p=181","title":{"rendered":"GEE"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_69_1 counter-hierarchy ez-toc-counter ez-toc-transparent ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">\u76ee\u5f55<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/lxylp.com\/?p=181\/#%E5%9F%BA%E7%A1%80%E7%9F%A5%E8%AF%86\" title=\"\u57fa\u7840\u77e5\u8bc6\">\u57fa\u7840\u77e5\u8bc6<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/lxylp.com\/?p=181\/#GEE%E8%AF%AD%E6%B3%95\" title=\"GEE\u8bed\u6cd5\">GEE\u8bed\u6cd5<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/lxylp.com\/?p=181\/#%E8%8E%B7%E5%8F%96%E5%BD%B1%E5%83%8FImage\" title=\"\u83b7\u53d6\u5f71\u50cf(Image)\">\u83b7\u53d6\u5f71\u50cf(Image)<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/lxylp.com\/?p=181\/#%E5%8A%A0%E8%BD%BD%E6%98%BE%E7%A4%BA_Sentinel-2\" title=\"\u52a0\u8f7d\u663e\u793a Sentinel-2\">\u52a0\u8f7d\u663e\u793a Sentinel-2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/lxylp.com\/?p=181\/#%E5%8A%A0%E8%BD%BD%E6%98%BE%E7%A4%BA_Landsat\" title=\"\u52a0\u8f7d\u663e\u793a Landsat\">\u52a0\u8f7d\u663e\u793a Landsat<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/lxylp.com\/?p=181\/#%E5%AE%9A%E9%87%8F%E6%8C%87%E6%95%B0\" title=\"\u5b9a\u91cf\u6307\u6570\">\u5b9a\u91cf\u6307\u6570<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/lxylp.com\/?p=181\/#%E8%AE%A1%E7%AE%97_NDVI\" title=\"\u8ba1\u7b97 NDVI\">\u8ba1\u7b97 NDVI<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/lxylp.com\/?p=181\/#%E8%AE%A1%E7%AE%97_NDWI\" title=\"\u8ba1\u7b97 NDWI\">\u8ba1\u7b97 NDWI<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/lxylp.com\/?p=181\/#%E8%AE%A1%E7%AE%97EVI\" title=\"\u8ba1\u7b97EVI\">\u8ba1\u7b97EVI<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/lxylp.com\/?p=181\/#image_%E9%80%BB%E8%BE%91%E8%BF%90%E7%AE%97\" title=\"image \u903b\u8f91\u8fd0\u7b97\">image \u903b\u8f91\u8fd0\u7b97<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/lxylp.com\/?p=181\/#image_%E5%88%86%E5%B1%82%E6%8A%BD%E6%A0%B7\" title=\"image \u5206\u5c42\u62bd\u6837\">image \u5206\u5c42\u62bd\u6837<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/lxylp.com\/?p=181\/#image_%E4%B9%8B_blend_%E5%92%8C_where\" title=\"image \u4e4b blend \u548c where\">image \u4e4b blend \u548c where<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/lxylp.com\/?p=181\/#image_%E4%B9%8B_unmask\" title=\"image \u4e4b unmask\">image \u4e4b unmask<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/lxylp.com\/?p=181\/#List_%E5%92%8C_collection%E6%A6%82%E5%BF%B5\" title=\"List \u548c collection\u6982\u5ff5\">List \u548c collection\u6982\u5ff5<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/lxylp.com\/?p=181\/#List_%E6%A6%82%E5%BF%B5\" title=\"List \u6982\u5ff5\">List \u6982\u5ff5<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/lxylp.com\/?p=181\/#List_%E5%B8%B8%E7%94%A8%E5%87%BD%E6%95%B0\" title=\"List \u5e38\u7528\u51fd\u6570\">List \u5e38\u7528\u51fd\u6570<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/lxylp.com\/?p=181\/#List_%E4%B9%8B_map\" title=\"List \u4e4b map\">List \u4e4b map<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/lxylp.com\/?p=181\/#ImageCollection\" title=\"ImageCollection\">ImageCollection<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/lxylp.com\/?p=181\/#ImageCollection_%E5%87%BD%E6%95%B0\" title=\"ImageCollection \u51fd\u6570\">ImageCollection \u51fd\u6570<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%9F%BA%E7%A1%80%E7%9F%A5%E8%AF%86\"><\/span>\u57fa\u7840\u77e5\u8bc6<span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p>GEE = Google Earth Engine<br>\u6d77\u91cf\u9065\u611f\u6570\u636e<br>\u96c6\u6210\u4f17\u591a\u7b97\u6cd5<br>\u5927\u8303\u56f4\u5904\u7406\u80fd\u529b<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"GEE%E8%AF%AD%E6%B3%95\"><\/span>GEE\u8bed\u6cd5<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th><\/th><th>\u672c\u5730(client)<\/th><th>GEE(server)<\/th><\/tr><\/thead><tbody><tr><td>\u7b26\u4e32<\/td><td><code>var str=\"hello\";<\/code><\/td><td><code>var str=ee.String(\"hello\")<\/code><\/td><\/tr><tr><td>\u6570\u5b57<\/td><td><code>var num=3;<\/code><\/td><td><code>var num=ee.Number(3)<\/code><\/td><\/tr><tr><td>\u5217\u8868<\/td><td><code>var lst=[1,2,3];<\/code><\/td><td><code>var lst=ee.List([1,2,3])<\/code><\/td><\/tr><tr><td>\u5bf9\u8c61<\/td><td><code>var obj={a1:\"x\",a2:2,a3:[1,2,3]};<\/code><\/td><td><code>var obj=ee.Dictionary({a1:\"x\",a2:2,a3:[1,2,3]})<\/code><\/td><\/tr><tr><td>\u51fd\u6570<\/td><td><code>function a(e){return e;}<\/code><\/td><td><code>function a(e){return e;}<\/code><\/td><\/tr><tr><td><code>print(num)<\/code><\/td><td><code>print(num+2)<\/code><\/td><td><code>print(num.add(2))<\/code>,<code>print(num.getinfo()+2)<\/code><\/td><\/tr><tr><td><\/td><td><code>for(var i=0; i&lt;lst.size();i++){print(i)}<\/code><\/td><td><code>for(var i=0; i&lt;lst.size().getInfo();i++){print(i)}<\/code><\/td><\/tr><tr><td><code>print(str)<\/code><\/td><td><code>print(str+',\"world\"')<\/code><\/td><td><code>print(str.getInfo()+', \"GEE\"')<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>\u5b9e\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>var m_string = ee.String('Hello, GEE');\nvar m_num = ee.Number(42);\nvar m_list = ee.List(&#91;0,1,2,3]);\nvar m_dict = ee.Dictionary({\n    e:Math.E, \n    pi:Math.PI, \n    phi: (1+Math.sqrt(5))\/2\n});\nfunction function(element){\n    return element;\n}<\/code><\/pre>\n\n\n\n<p>\u5feb\u6377\u952e<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u529f\u80fd<\/th><th>\u5feb\u6377\u952e<\/th><\/tr><\/thead><tbody><tr><td>\u5728\u82f1\u6587\u6a21\u5f0f\u4e0b<\/td><td><code>\/<\/code><\/td><\/tr><tr><td>\u6ce8\u91ca\uff1a<\/td><td><code>ctrl+\/<\/code><\/td><\/tr><tr><td>\u81ea\u52a8\u8865\u5168<\/td><td><code>ctrl+space<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%8E%B7%E5%8F%96%E5%BD%B1%E5%83%8FImage\"><\/span>\u83b7\u53d6\u5f71\u50cf(Image)<span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Function<\/th><th>conception<\/th><\/tr><\/thead><tbody><tr><td><code>ee.ImageCollection<\/code><\/td><td>Image Collection<\/td><\/tr><tr><td><code>ee.Image<\/code><\/td><td>Image<\/td><\/tr><tr><td><strong>Image\u7684\u521b\u5efa<\/strong><\/td><td><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ 1. \u4f7f\u7528 image id \u521b\u5efa\nvar img=ee.Image('JAXA\/ALOS\/AW3D30\/V2_2');\nprint(img)\nprint(img.bandNames()) \/\/\u663e\u793a\u6ce2\u6bb5\u6570\n\/\/ 1.1 \u52a0\u8f7d multiband \u5f71\u50cf\nvar vipara={\n  bands: &#91;'B5','B4','B3'],\n  min: 0,\n  max: 0.5,\n  gama: &#91;0.95, 1.1, 1]\n};\nMap.setCenter(-122.1899,37.50,10);\nMap.addLayer(img,vipara,'false color'\uff0cfalse); \/\/ \u5148\u4e0d\u663e\u793a\n\n\/\/ 2. \u4f7f\u7528 imageCollection \u521b\u5efa\nvar img=ee.ImageCollection('COPERNICUS\/S2_SR')\n                .filterBounds(ee.Geometry.Point(110.39, 19.98))\n                .filterDate('2021-01-01', '2021-12-31')\n                .sort('CLOUDY_PIXEL_PERCENTAGE')\n                .first();\nMap.centerObject(img\uff0c11);\nprint(img)\nMap.addLayer(img, {bands: &#91;'B4', 'B3', 'B2'], min: 0, max: 2000}, 'first');<\/code><\/pre>\n\n\n\n<p><strong>\u53ef\u7528\u6570\u636e\u6c47\u603b<\/strong>\uff1a<br>Earth Engine Data Catalog\uff0c <a href=\"https:\/\/developers.google.com\/earth-engine\/datasets\">landsat, Sentinel-2, Sentinel-1, MODIS \u2026<\/a><\/p>\n\n\n\n<p>\u5e2e\u52a9\u6587\u4ef6API <a href=\"https:\/\/developers.google.com\/earth-engine\/apidocs\">DOCS<\/a><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8A%A0%E8%BD%BD%E6%98%BE%E7%A4%BA_Sentinel-2\"><\/span>\u52a0\u8f7d\u663e\u793a Sentinel-2<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ load image through ImageCollection \nvar first = ee.ImageCollection('COPERNICUS\/S2_SR')\n                .filterBounds(ee.Geometry.Point(110.39, 19.98))\n                .filterDate('2021-01-01', '2021-12-31')\n                .sort('CLOUDY_PIXEL_PERCENTAGE')\n                .first();\nMap.centerObject(first);\nMap.addLayer(first, {bands: &#91;'B4', 'B3', 'B2'], min: 0, max: 2000}, 'first'); \/\/\u52a0\u8f7d\u663e\u793a\u591a\u6ce2\u6bb5<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8A%A0%E8%BD%BD%E6%98%BE%E7%A4%BA_Landsat\"><\/span>\u52a0\u8f7d\u663e\u793a Landsat<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>var image = ee.ImageCollection(\"LANDSAT\/LC08\/C01\/T1_SR\")\n              .filterBounds(geometry)\n              .filterDate('2020-01-01','2020-12-31')\n              .sort('CLOUDY_PIXEL_PERCENTAGE')\n              .first();\nprint(image)\n\/\/ Center the map and display the image.\nMap.setCenter(110.39,19.98); \/\/\nMap.centerObject(image,12)\nMap.addLayer(image, {bands: &#91;'B4','B3','B2'], min: 0,max: 2000}, 'Landsat-8'); \/\/\u52a0\u8f7d\u663e\u793a\u591a\u6ce2\u6bb5<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%AE%9A%E9%87%8F%E6%8C%87%E6%95%B0\"><\/span>\u5b9a\u91cf\u6307\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u52a0\u8f7d\u5f71\u50cf Load an image.\nvar image = ee.ImageCollection(\"LANDSAT\/LC08\/C01\/T1_TOA\")\n              .filterBounds(geometry)\n              .filterDate('2020-01-01','2020-12-31')\n              .sort('CLOUDY_PIXEL_PERCENTAGE')\n              .first();\nprint(\"image\", image);\n\/\/ Define the visualization parameters.\nvar vizParams = {\n  bands: &#91;'B5', 'B4', 'B3'],\n  min: 0, \/\/ or min: &#91;0, 0.2, 0.3],\n  max: 0.5, \/\/ or max: &#91;0.8, 0.5, 0.7],\n  gamma: &#91;0.95, 1.1, 1]\n};\n\/\/ \u663e\u793a\u5f71\u50cf Center the map and display the image.\nMap.setCenter(110.39,19.98, 10); \/\/ \nMap.addLayer(image, vizParams, 'faulse color image');<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AE%A1%E7%AE%97_NDVI\"><\/span>\u8ba1\u7b97 NDVI<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u8ba1\u7b97NDVI compute ndvi\n\/\/ defien the visualizaiton parameters\nvar visParam_NDVI = {\nmin: -0.2,\nmax: 1,\npalette: 'FFFFFF, CE7E45, DF923D, F1B555, FCD163, 99B718, 74A901, 66A000, 529400,' +\n  '3E8601, 207401, 056201, 004C00, 023B01, 012E01, 011D01, 011301'\n}; \/\/\u52a0\u8f7d\u663e\u793a\u5355\u6ce2\u6bb5\u8981\u7528\u7684\u53c2\u6570\n\nvar imgNDVI = image.normalizedDifference(&#91;\"B5\", \"B4\"]).rename(\"imgNDVI\") \/\/rename\n                  .set(\"system:time_start\", image.get(\"system:time_start\"))\n                  .set(\"CLOUD_COVER\",image.get(\"CLOUD_COVER\"))\n                  .set(\"UTM_ZONE\", image.get(\"UTM_ZONE\"))\n                  .set(\"WRS_PATH\", image.get(\"WRS_PATH\"))\n                  .set(\"WRS_ROW\",image.get(\"WRS_ROW\"));\nMap.addLayer(imgNDVI, visParam_NDVI,'image NDVI'); \/\/\u52a0\u8f7d\u663e\u793a\u5355\u6ce2\u6bb5\nprint(\"imgNDVI\", imgNDVI);<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AE%A1%E7%AE%97_NDWI\"><\/span>\u8ba1\u7b97 NDWI<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u8ba1\u7b97NDWI compute ndwi\nvar imgMNDWI = image.normalizedDifference(&#91;\"B3\", \"B6\"]).rename(\"imgNDWI\");\n\/\/\u8bbe\u5b9a\u6700\u5927\u503c\u3001\u6700\u5c0f\u503c\u7684\u989c\u8272\nMap.addLayer(imgMNDWI, {min:0, max:1, palette:&#91;'#000000', '0000FF']},'image MNDWI'); \n\/\/\u8bbe\u7f6e\u63a9\u819c\uff0c\u5e76\u5c06\u989c\u8272\u8bbe\u7f6e\u4e3a blue\nMap.addLayer(imgMNDWI.selfMask(), {palette:&#91;'0000FF']},'image MNDWI2');\n\/\/\u5c06 \u5927\u4e8e0 \u7684\u503c\u8bbe\u7f6e\u4e3a red\nvar waterMask = imgMNDWI.gte(0);\nMap.addLayer(waterMask.selfMask(), {'palette':'red'}, 'waterMask');<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AE%A1%E7%AE%97EVI\"><\/span>\u8ba1\u7b97EVI<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u8ba1\u7b97EVI Compute the EVI using an expression.\nvar evi = image.expression(\n    '2.5 * ((NIR - RED) \/ (NIR + 6 * RED - 7.5 * BLUE + 1))', {\n      'NIR': image.select('B5'),\n      'RED': image.select('B4'),\n      'BLUE': image.select('B2')\n});\nMap.addLayer(evi, {min:-1, max:1, palette:&#91;'FF0000', '00FF00']}, 'EVI');\n\nfunction EVI_Calculate(img) {\n  \/\/ .multiply(0.0001) \nvar blue = img.select(\"B2\").multiply(0.0001);\nvar red = img.select(\"B4\").multiply(0.0001);\nvar nir = img.select(\"B5\").multiply(0.0001);\nvar evi = img.expression(\n  '2.5 * ((B8 - B3) \/ (B8 + 6 * B3 - 7.5 * B2 + 1))',\n  {\n    \"B2\": blue,\n    \"B3\": red,\n    \"B8\": nir\n  }\n).rename('EVI');\nreturn evi;\n}<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"image_%E9%80%BB%E8%BE%91%E8%BF%90%E7%AE%97\"><\/span>image \u903b\u8f91\u8fd0\u7b97<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u5bfc\u5165\u7814\u7a76\u533a(\u5317\u4eac)\u5206\u7c7b\u3001\u533a\u57df\u8fb9\u754c\u7b49\u6570\u636e\nImports (4 entries)\nvar CLCD_2020: Image users\/pathToData1\nvar CLCD_2000: Image users\/pathToData2\nvar AOI: Polygon, 4 vertices\nvar ChinaProvince: Table user\/PathToChinaProvince\n\n\/\/ \u83b7\u53d6\u5e76\u52a0\u8f7d \u5317\u4eac\u5e02 \u533a\u57df\nvar Beijing = ChinaProvince.filter(ee.Filter.eq(\"City\",'\u5317\u4eac\u5e02'));\nvar roi = Beijing;\nMap.centerObject(roi);\nMap.addLayer(roi, {'color':'blue'}, 'studyArea',true, 0.5);\n\n\/********************************************************\n1-Cropland\n2-Forest\n3-Shrub\n4-Grassland\n5-Water\n6-Sonw\/Ice\n7-Barren\n8-Impervious\n9-Wetland\n********************************************************\/\n\n\/\/ \u52a0\u8f7d 2020 \u5e74\u5206\u7c7b\u6570\u636e\uff0c\u5e76\u4ee5\u968f\u673a\u989c\u8272\u663e\u793a\nvar CLCD_2020 = CLCD_2020.clip(roi);\nMap.addLayer(CLCD_2020.randomVisualizer(), null, 'CLCD_2020',false);\nprint(CLCD_2020.bandNames());\n\n\/\/ \u63d0\u53d6\u4e0d\u900f\u6c34\u5c42\uff0c\u5373 urban area\uff0c\u5e76\u663e\u793a\nvar urban_beijing_2020 = CLCD_2020.clip(roi).eq(8);\nvar urban_beijing_2000 = CLCD_2000.clip(roi).eq(8);\nMap.addLayer(urban_beijing_2020,{palette:&#91;'gray','red']},'urban2020',false)\n\n\/\/ \u8ba1\u7b972000\u548c2020\u5e74\u90fd\u4e3a\u4e0d\u900f\u6c34\u5c42\u7684\u533a\u57df\nvar urban_beijing_or = urban_beijing_2020.or(urban_beijing_2000);\n\/\/ Map.addLayer(urban_beijing_or.selfMask(),{'palette':&#91;'red','green']},'urban_bjor');\nMap.addLayer(urban_beijing_or.selfMask(), {'palette':&#91;'red']},'urban_beijing_or',false);\n\n\/\/ \u8ba1\u7b97 \u540c\u4e3a \u4e0d\u900f\u6c34\u5c42\u7684\u533a\u57df\nvar urban_beijing_and = urban_beijing_2020.and(urban_beijing_2000);\nMap.addLayer(urban_beijing_and.selfMask(), {'palette':&#91;'yellow']},'urban_beijing_and');<\/code><\/pre>\n\n\n\n<p>\u95ee\u9898<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u8ba1\u7b97\u6bcf\u4e00\u7c7b\u6837\u672c\u6570\uff1f<\/li>\n\n\n\n<li>\u8ba1\u7b97\u7c7b\u522b\u6570\uff1f<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"image_%E5%88%86%E5%B1%82%E6%8A%BD%E6%A0%B7\"><\/span>image \u5206\u5c42\u62bd\u6837<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>\u5373\uff0c\u4ece\u5df2\u6709\u7684\u7c7b\u522b\u4e2d\u5f97\u5230\u6837\u672c\u70b9<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u5bfc\u5165\u7814\u7a76\u533a(\u5317\u4eac)\u5206\u7c7b\u3001\u533a\u57df\u8fb9\u754c\u7b49\u6570\u636e\nImports (4 entries)\nvar CLCD_2020: Image users\/pathToData1\nvar AOI: Polygon, 4 vertices\nvar ChinaProvince: Table user\/PathToChinaProvince\n\n\/\/ \u62bd\u53d6\u5e76\u663e\u793a\u7814\u7a76\u533a\u4f4d\u7f6e\nvar Beijing = ChinaProvince.filter(ee.Filter.eq(\"City\",'\u5317\u4eac\u5e02'));\nvar roi = Beijing;\nMap.centerObject(roi);\nMap.addLayer(roi, {'color':'grey'}, 'studyArea');\n\n\/********************************************************\n1-Cropland\n2-Forest\n3-Shrub\n4-Grassland\n5-Water\n6-Sonw\/Ice\n7-Barren\n8-Impervious\n9-Wetland\n********************************************************\/\n\/\/ \u4ee5\u968f\u673a\u989c\u8272\u663e\u793a\u5317\u4eac\u5e02 2020\u5e74\u5206\u7c7b\u6570\u636e\nvar CLCD_2020 = CLCD_2020.clip(roi);\nMap.addLayer(CLCD_2020.randomVisualizer(), null, 'CLCD_2020',false);\n\n\/\/ \u63d0\u53d6\u5317\u4eac 2020\u5e74 \u4e0d\u900f\u6c34\u5c42\u533a\u57df\uff0c\u5e76\u5c06\u6ce2\u6bb5\u547d\u540d\u4e3a impervious\nvar impervious_beijing = CLCD_2020.eq(8).clip(roi).rename('Impervious')\nprint(impervious_beijing)\n\/\/ \u4e3a\u5206\u5c42\u62bd\u6837\u505a\u51c6\u5907\nvar impervious_beijing = CLCD_2020.eq(8).clip(roi).rename('Impervious')\n                                  .set('system:footprint',roi.geometry());\nprint(impervious_beijing)\nMap.addLayer(impervious_beijing.selfMask(), {'palette':&#91;'red']},'impervious_beijing');\n\n\/\/ \u4ece\u4e0d\u900f\u6c34\u5c42\u6ce2\u6bb5\u63d0\u53d6 2000 \u4e2a\u6837\u672c\u70b9\nvar impervious_sample = impervious_beijing.selfMask().stratifiedSample({\n  numPoints:2000,\n  classBand:'Impervious',\n  geometries:true\n});\nMap.addLayer(impervious_sample, null, 'impervious_sample');\nprint(\"impervious_sample size\",impervious_sample.size())<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"image_%E4%B9%8B_blend_%E5%92%8C_where\"><\/span>image \u4e4b blend \u548c where<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u5bfc\u5165\u7814\u7a76\u533a(\u5317\u4eac)\u5206\u7c7b\u3001\u533a\u57df\u8fb9\u754c\u7b49\u6570\u636e\nImports (4 entries)\nvar CLCD_2020: Image users\/pathToData1\nvar CLCD_2000: Image users\/pathToData2\nvar AOI: Polygon, 4 vertices\nvar ChinaProvince: Table user\/PathToChinaProvince\n\n\/\/ \u83b7\u53d6\u5e76\u52a0\u8f7d \u5317\u4eac\u5e02 \u533a\u57df\nvar Beijing = ChinaProvince.filter(ee.Filter.eq(\"City\",'\u5317\u4eac\u5e02'));\nvar roi = Beijing;\nMap.centerObject(roi,8); \/\/ \u7f29\u653e\u6bd4\u4f8b\u4e3a 8 &#91;0-24]\nMap.addLayer(roi, {'color':'grey'}, 'studyArea');\n\n\/\/ \u52a0\u8f7d\u5e76\u663e\u793a\u7814\u7a76\u533a \u54e8\u5175\u6570\u636e\nvar imgS2 = ee.ImageCollection('COPERNICUS\/S2_SR')\n                .filterBounds(roi)\n                .filterDate('2020-01-01', '2020-12-31')\n                .sort('CLOUDY_PIXEL_PERCENTAGE',false)\n                .mosaic().clip(roi)\n                .divide(1e4);\nMap.addLayer(imgS2, {bands: &#91;'B4', 'B3', 'B2'], min: 0, max: 0.3}, 'imgS2');\n\nvar urban = CLCD_2020.clip(roi).eq(8);\nMap.addLayer(urban.selfMask(), {'palette':'yellow'}, 'urban');\n\n\/\/ blend\nvar imgS2_blend_urban = imgS2.blend(urban);\nMap.addLayer(imgS2_blend_urban, {bands:&#91;'B4', 'B3', 'B2'],min:0,max:0.3},'imgS2_blend_urban');\n\n\/\/ where\nvar tmp_red = imgS2.select('B4').where(urban,1);\nvar tmp_green = imgS2.select('B3').where(urban,0);\nvar tmp_blue = imgS2.select('B2').where(urban,0); \nvar tmp = ee.Image.cat(&#91;tmp_red,tmp_green,tmp_blue]);                            \nMap.addLayer(tmp, {bands:&#91;'B4', 'B3', 'B2'],min:0,max:0.3},'tmp');<\/code><\/pre>\n\n\n\n<p>\u6ca1\u542c\u660e\u767d\uff0c\u56de\u5934\u81ea\u5df1\u770b\u5e2e\u52a9<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"image_%E4%B9%8B_unmask\"><\/span>image \u4e4b unmask<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u5bfc\u5165\u7814\u7a76\u533a(\u5317\u4eac)\u5206\u7c7b\u3001\u533a\u57df\u8fb9\u754c\u7b49\u6570\u636e\nImports (4 entries)\nvar CLCD_2020: Image users\/pathToData1\nvar CLCD_2000: Image users\/pathToData2\nvar AOI: Polygon, 4 vertices\nvar ChinaProvince: Table user\/PathToChinaProvince\n\n\/\/ \u83b7\u53d6\u5e76\u52a0\u8f7d \u5317\u4eac\u5e02 \u533a\u57df\nvar Beijing = ChinaProvince.filter(ee.Filter.eq(\"City\",'\u5317\u4eac\u5e02'));\nvar roi = Beijing;\nMap.centerObject(roi);\nMap.addLayer(roi, {'color':'grey'}, 'studyArea');\n\n\/\/ Return the bounding box of this geometry.\nvar roiBound = roi.geometry().bounds();\nMap.addLayer(roiBound, {'color':'red'}, 'StudyBound');\n\nvar imgS2 = ee.ImageCollection('COPERNICUS\/S2_SR')\n                .filterBounds(roi)\n                .filterDate('2020-01-01', '2020-12-31')\n                .sort('CLOUDY_PIXEL_PERCENTAGE',false)\n                .mosaic().clip(roi)\n                .divide(1e4);\nMap.addLayer(imgS2, {bands: &#91;'B4', 'B3', 'B2'], min: 0, max: 0.3}, 'imgS2');\n\nvar CLCD_2020 = CLCD_2020.clip(roi);\nMap.addLayer(CLCD_2020.randomVisualizer(), null, 'CLCD_2020');\n\n\/\/ \u5982\u679c\u7c7b\u522b\u503c\u662f\u4ece 0 \u5f00\u59cb\uff0c\u7c7b\u522b\u503c+1\uff0c\u5e76\u5c06\u80cc\u666f\u503c\u8bbe\u7f6e\u4e3a -999\nvar CLCD_2020_filled = CLCD_2020.add(1).unmask(-999).clip(roiBound);\nMap.addLayer(CLCD_2020_filled.randomVisualizer(), null, 'CLCD_2020_filled');<\/code><\/pre>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"List_%E5%92%8C_collection%E6%A6%82%E5%BF%B5\"><\/span>List \u548c collection\u6982\u5ff5<span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u65e0\u5e8f\u7ed3\u6784<\/th><th>\u6709\u5e8f\u7ed3\u6784<\/th><\/tr><\/thead><tbody><tr><td><code>ee.ImageColletion<\/code><\/td><td><code>ee.List<\/code><\/td><\/tr><tr><td><code>ee.FeatureCollection<\/code><\/td><td><code>ee.Array<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"List_%E6%A6%82%E5%BF%B5\"><\/span>List \u6982\u5ff5<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>\u4e07\u7269\u53ef\u4e3a List<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u7a7a\uff1a <code>var lst=[]<\/code>, var lst=ee.List([])<\/li>\n\n\n\n<li>\u6570\u503c\uff1a <code>var lst=[1, 2, 3]<\/code>, var lst=ee.List([1,2,3])<\/li>\n\n\n\n<li>\u5b57\u7b26\u4e32\uff1a <code>var lst=['a', 'b', 'c']<\/code><\/li>\n\n\n\n<li>\u6805\u683c\u6570\u636e\uff1a<\/li>\n\n\n\n<li>\u9002\u91cf\u6570\u636e\uff1a<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"List_%E5%B8%B8%E7%94%A8%E5%87%BD%E6%95%B0\"><\/span><code>List<\/code> \u5e38\u7528\u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>sequence<\/code>\u51fd\u6570<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>var tmpList1 = ee.List(&#91;1,2,3,4,5]);\nprint(\"tmpList:\", tmpList1);\n\n\/\/ \u51fd\u6570\u751f\u6210\u5e8f\u5217\nvar tmpList2 = ee.List.sequence(1,10);\nprint(\"tmpList2:\", tmpList2);<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>cat<\/code> \u62fc\u63a5\u51fd\u6570<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ cat, \u62fc\u63a5list \nvar tmpList3 = tmpList1.cat(tmpList2);\nprint(tmpList3);<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>get<\/code> \u83b7\u53d6\u5143\u7d20\u503c<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ get\uff0c\u83b7\u53d6\u5143\u7d20\u503c \n\/\/ note that the index starts with zero\nprint(\"tmpList3 get(1)\", tmpList3.get(1));<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>size<\/code> \u6d4b\u91cflist\u5927\u5c0f<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ size \nvar listSize = tmpList3.size();\nprint(\"listSize size\", listSize);<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>add<\/code> \u8ffd\u52a0\u5143\u7d20<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ add, \u8ffd\u52a0\u5143\u7d20\nvar tmpList3 = tmpList3.add('GEE');\nprint(\"tmpList3 add\",tmpList3);<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>insert<\/code> \u63d2\u5165\u5143\u7d20<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ insert, \u63d2\u5165\u5143\u7d20\nvar tmpList3 = tmpList3.insert(0,'a');\nprint(\"tmpList3 insert\",tmpList3);<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>sort<\/code> \u6392\u5e8f<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ sort should be run for list with values of same type\nvar tmpList3 = tmpList3.sort();\nprint(\"tmpList3 sort\",tmpList3);<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>slice<\/code> \u5207\u7247<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u5207\u7247\nvar tmpList3 = tmpList3.slice(0,5,2); \/\/ (start,end,step)\nprint(\"tmpList3 slice\",tmpList3);<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"List_%E4%B9%8B_map\"><\/span>List \u4e4b map<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u5ba2\u6237\u7aef list\nvar clientList = &#91;];\nfor(var i = 0; i &lt; 8; i++) {\n  clientList.push(i + 1);\n}\nprint('clst',clientList);\n\n\/\/ \u670d\u52a1\u5668 list\nvar serverList = ee.List.sequence(0, 7);\nserverList = serverList.map(function(n) {\n  return ee.Number(n).add(1);\n}); \/\/ \u9690\u51fd\u6570\nprint('slst',serverList);\n\n\/\/ \u4f7f\u7528 map \u7684\u53e6\u5916\u4e00\u79cd\u65b9\u5f0f\nfunction addNum(n){\n  return ee.Number(n).add(1); \/\/ \u7528Number\u5f3a\u5236\u8f6c\u6362\u4e3a\u670d\u52a1\u5668\u7248\u672c\n}\nvar serverList = ee.List.sequence(0,7);\nserverList = serverList.map(addNum);\nprint('slst',serverList)\n\n\/\/ list \u8fd4\u56de\u503c\u4e3a feature\nvar tmpList = ee.List.sequence(0, 11);\nprint(\"tmpList\",tmpList);\nvar tmpListV2 = tmpList.map(function(item){\n  var tmpFea = ee.Feature(null).set('Num',item);\n  return tmpFea;\n});\nprint(\"tmpListV2\",tmpListV2);\n\n\/\/ list \u8fd4\u56de\u503c\u4e3a image\nvar tmpListV3 = tmpList.map(function(item){\n  var tmpImg = ee.Image.constant(item).set('Num',item)\/\/.set('month',ee.Number(item).add(1));\n  return tmpImg;\n});\nprint(\"tmpListV3\",tmpListV3);\n\n\/\/ \u67e5\u627e\u6ee1\u8db3\u6761\u4ef6\u7684\u5143\u7d20\u4f4d\u7f6e\nprint(serverList.indexOf(4))<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>list \u8fd4\u56de\u503c\u53ef\u4ee5\u548c\u539f\u6765 list \u4e0d\u540c<\/li>\n\n\n\n<li>Map \u51fd\u6570\u6ca1\u6709\u8003\u8651\u5bf9\u5e94\u5143\u7d20\u4e4b\u95f4\u7684\u987a\u5e8f\u7ed3\u6784\u5173\u7cfb<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"ImageCollection\"><\/span>ImageCollection<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Landsat<\/li>\n\n\n\n<li>Sentinel-1<\/li>\n\n\n\n<li>Sentinel-2<\/li>\n\n\n\n<li>MODIS<\/li>\n\n\n\n<li>Cropland Datasets<\/li>\n<\/ul>\n\n\n\n<p>GEE <a href=\"https:\/\/developers.google.com\/earth-engine\/datasets\">Dataset catalog<\/a><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"ImageCollection_%E5%87%BD%E6%95%B0\"><\/span>ImageCollection \u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u5bfc\u5165\u77e2\u91cf\u6587\u4ef6\nImports (1 entry)\nvar AOI: Polygon, 4 vertices\n\/\/ \u52a0\u8f7d\u5e76\u663e\u793a\u77e2\u91cf\u6587\u4ef6\nvar roi = AOI;\nMap.centerObject(roi,7);\nMap.addLayer(roi, {'color':'grey'}, 'StudyArea');\n\/\/ imageCollection \u65cb\u8f6c\u5f71\u50cf\nvar S2Col = ee.ImageCollection('COPERNICUS\/S2_SR')\n              .filterBounds(roi)\n              .filterDate('2020-11-01','2020-12-01');\n              .map(function(img){return img.clip(roi) }) \/\/\u63d0\u524d clip\n              .select(&#91;'B4','B3','B2'],&#91;'red','green','blue']); \/\/\u9009\u62e9\u6307\u5b9a\u6ce2\u6bb5\uff0c\u5e76\u91cd\u547d\u540d\n\nvar vis = {bands: &#91;'B4', 'B3', 'B2'], min: 0, max: 5000};<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>first<\/code> \u7b2c\u4e00\u666f\u5f71\u50cf<br>&#8220;`javascript<br>\/\/ first image<br>var S2Col_first = S2Col.first();<br>Map.addLayer(S2Col_first, vis, &#8216;S2Col_first&#8217;);<br>print(&#8220;S2Col_first&#8221;,S2Col_first);<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>- `mean`<\/code><\/pre>\n\n\n\n<p>javascript<br>\/\/ \u6240\u6709\u7b2c i \u6ce2\u6bb5\u5728\u8be5\u50cf\u7d20\u4f4d\u7f6e\u7684\u5747\u503c<br>var S2Col_mean = S2Col.mean().clip(roi);<br>Map.addLayer(S2Col_mean, vis, &#8216;S2Col_mean&#8217;);<br>print(&#8220;S2Col_mean&#8221;,S2Col_mean);<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>- `median`<\/code><\/pre>\n\n\n\n<p>javascript<br>\/\/ \u6240\u6709\u7b2c i \u6ce2\u6bb5\u5728\u8be5\u50cf\u7d20\u4f4d\u7f6e\u7684\u4e2d\u503c<br>var S2Col_median = S2Col.median(); \/\/\u6240\u6709\u4e0e\u7814\u7a76\u533a\u76f8\u4ea4\u7684\u5f71\u50cf<br>Map.addLayer(S2Col_median, vis, &#8216;S2Col_median&#8217;);<br>print(&#8220;S2Col_median&#8221;,S2Col_median);<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>- `size`<\/code><\/pre>\n\n\n\n<p>javascript<br>\/\/ \u5171\u6709 47 \u666f\u5f71\u50cf\uff1f<br>var S2Col_size = S2Col.size();<br>print(&#8220;S2Col_size&#8221;,S2Col_size);<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>## ImageCollection \u4e4b Map\n\u53ea\u80fd\u8fd4\u56de `feature` \u6216 `image`<\/code><\/pre>\n\n\n\n<p>javascript<br>\/\/ \u5bfc\u5165\u77e2\u91cf\u6587\u4ef6<br>Imports (1 entry)<br>var AOI: Polygon, 4 vertices<br>\/\/ \u52a0\u8f7d\u5e76\u663e\u793a\u7814\u7a76\u533a<br>var roi = AOI;<br>Map.centerObject(roi);<br>Map.addLayer(roi, {&#8216;color&#8217;:&#8217;grey&#8217;}, &#8216;StudyArea&#8217;);<\/p>\n\n\n\n<p>\/\/ \u5b9a\u4e49\u51fd\u6570<br>function addNDVI_V1(img){<br>var ndvi = ee.Image(img).normalizedDifference([&#8216;B8&#8242;,&#8217;B4&#8217;]).rename(&#8216;NDVI&#8217;);<br>\/\/return img.addBands(ndvi);<br>return ee.Feature(null);<br>}<\/p>\n\n\n\n<p>function addNDVI_V2(img){<br>var ndvi = ee.Image(img).normalizedDifference([&#8216;B8&#8242;,&#8217;B4&#8217;]).rename(&#8216;NDVI&#8217;);<br>return ndvi;<br>}<\/p>\n\n\n\n<p>function addNDVI_V3(img){<br>var ndvi = ee.Image(img).normalizedDifference([&#8216;nir&#8217;,&#8217;red&#8217;]).rename(&#8216;NDVI&#8217;);<br>return img.addBands(ndvi);<br>}<\/p>\n\n\n\n<p>var S2Col_V1 = ee.ImageCollection(&#8216;COPERNICUS\/S2_SR&#8217;)<br>.filterBounds(roi)<br>.filterDate(&#8216;2020-11-01&#8242;,&#8217;2020-12-01&#8217;)<br>.map(addNDVI_V1);<\/p>\n\n\n\n<p>var S2Col_V2 = ee.ImageCollection(&#8216;COPERNICUS\/S2_SR&#8217;)<br>.filterBounds(roi)<br>.filterDate(&#8216;2020-11-01&#8242;,&#8217;2020-12-01&#8217;)<br>.map(addNDVI_V2);<\/p>\n\n\n\n<p>var S2Col_V3 = ee.ImageCollection(&#8216;COPERNICUS\/S2_SR&#8217;)<br>.filterBounds(roi)<br>.filterDate(&#8216;2020-11-01&#8242;,&#8217;2020-12-01&#8217;)<br>.select([&#8220;B8&#8243;,&#8221;B4&#8221;],[&#8216;nir&#8217;,&#8217;red&#8217;])<br>.map(addNDVI_V3);<\/p>\n\n\n\n<p>print(&#8220;S2Col_V1&#8221;,S2Col_V1);<br>print(&#8220;S2Col_V2&#8221;,S2Col_V2);<br>print(&#8220;S2Col_V3&#8221;,S2Col_V3);<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>- \u6ca1\u542c\u660e\u767d\u5c06\u8fd9\u4e2a\u5185\u5bb9\u662f\u5e72\u5565\u7684\uff1f\u6ca1\u8bb2\u6e05\u695a\uff0c\u540e\u9762\u770b\u793a\u4f8b\u5427\n- `print`, `Map.addLayer` \u7b49\u5c5e\u4e8e\u672c\u5730\u51fd\u6570\uff0c\u6700\u597d\u4e0d\u8981\u51fa\u73b0\u5728 `GEE` \u670d\u52a1\u5668\u4ee3\u7801\u91cc\n\n## \u4f8b\u5b50\uff1a\u53ef\u7528\u6027\u5206\u6790\u4e0e\u9891\u7387\u8ba1\u7b97<\/code><\/pre>\n\n\n\n<p>javascript<br>var ChinaProvince = ee.FeatureCollection(&#8220;users\/studyroomGEE\/ChinaShp\/ChinaProvince&#8221;);<br>var Guangdong = ChinaProvince.filter(ee.Filter.eq(&#8220;City&#8221;,&#8217;\u5e7f\u4e1c\u7701&#8217;));<br>var roi = Guangdong;<br>Map.addLayer(roi, {&#8216;color&#8217;:&#8217;grey&#8217;}, &#8216;studyArea&#8217;);<br>Map.centerObject(roi);<\/p>\n\n\n\n<p>var year_start = 2020;<br>var year_end = 2020;<\/p>\n\n\n\n<p>var imgCol = ee.ImageCollection(&#8220;LANDSAT\/LC08\/C01\/T1_SR&#8221;)<br>.filterBounds(roi)<br>.filter(ee.Filter.calendarRange(year_start, year_end,&#8217;year&#8217;));<\/p>\n\n\n\n<p>\/\/ compute the image total size<br>var imgSize = imgCol.size(); \/\/filter\u540e\uff0c\u6570\u636e\u96c6\u4e2d\u5f71\u50cf\u7684\u4e2a\u6570\uff1f<br>print(&#8220;imgSize&#8221;,imgSize); \/\/ result is 265<\/p>\n\n\n\n<p>\/*<br>compute the image avaibility. There are several ways to achieve that.<br>1: use the count function; count \u8868\u793a\u6bcf\u4e2a\u5143\u7d20\u53ef\u7528\u7684\u5f71\u50cf\u7684\u6570\u91cf<br>2: use the sum function<br>**\/<br>var imgCount_V1 = imgCol.select(&#8220;B1&#8221;).count().clip(roi);<br>var imgCount_V2= imgCol.select(&#8220;B1&#8221;).map(function(img){<br>return img.multiply(0).add(1).toInt();<br>}).sum().clip(roi);<\/p>\n\n\n\n<p>\/\/ define image render parameters<br>var visParam = {<br>min: 10,<br>max: 40,<br>palette: &#8216;FFFFFF, CE7E45, DF923D, F1B555, FCD163, 99B718, 74A901, 66A000, 529400,&#8217; +<br>&#8216;3E8601, 207401, 056201, 004C00, 023B01, 012E01, 011D01, 011301&#8217;<br>};<\/p>\n\n\n\n<p>Map.addLayer(imgCount_V1,visParam,&#8221;imgCount_V1&#8243;,false);<br>Map.addLayer(imgCount_V2,visParam,&#8221;imgCount_V2&#8243;,false);<\/p>\n\n\n\n<p>\/*<br>compute the water frequency<br>**\/<br>var waterIndex = imgCol.map(function(img){<br>var mndwi = img.normalizedDifference([&#8216;B3&#8242;,&#8217;B6&#8217;]).gt(0).rename(&#8216;MNDWI&#8217;);<br>return img.addBands(mndwi);<br>})<br>var waterFrequency = waterIndex.select(&#8220;MNDWI&#8221;).sum().divide(imgCount_V1).clip(roi);<br>\/\/ \u8be5\u4f4d\u7f6e\u6240\u6709\u6c34\u4f53\u503c\u7684\u548c\uff0c\u9664\u4ee5\u5f71\u50cf\u7684\u4e2a\u6570<br>Map.addLayer(waterFrequency, {min: 0, max:1, palette: [&#8216;000000&#8217;, &#8216;0000FF&#8217;]}, &#8216;waterFrequency&#8217;)<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>- \u6b64\u5904\u53ef\u7528\u4e8e\u7ea2\u6811\u6797\u7684\u63d0\u53d6\uff0c\u600e\u4e48\u7528\uff1f\uff08\u690d\u88ab\u6307\u6570\u6982\u7387\u56fe\uff1f\uff09\n\n## \u4f8b\u5b50\uff1aimagecollection (\u6761\u5e26\u53f7\u5236\u4f5c)\n&#91;\u4ee3\u7801](https:\/\/code.earthengine.google.com\/f9ff81c85cc70d42f6771bcc0a0d8e6d)<\/code><\/pre>\n\n\n\n<p>javascript<br>var ChinaProvince = ee.FeatureCollection(&#8220;users\/studyroomGEE\/ChinaShp\/ChinaProvince&#8221;);<br>var Guangzhou = ChinaProvince.filter(ee.Filter.eq(&#8220;City&#8221;,&#8217;\u5e7f\u4e1c\u7701&#8217;));<br>var roi = Guangzhou;<br>Map.addLayer(roi, {&#8216;color&#8217;:&#8217;grey&#8217;}, &#8216;studyArea&#8217;);<br>Map.centerObject(roi);<\/p>\n\n\n\n<p>\/\/ set time parameter<br>var year_start = 2018;<br>var year_end = 2020;<br>var imgCol = ee.ImageCollection(&#8220;LANDSAT\/LC08\/C01\/T1_SR&#8221;)<br>.filterBounds(roi)<br>.filter(ee.Filter.calendarRange(year_start, year_end,&#8217;year&#8217;))<br>Map.addLayer(imgCol.first());<br>print(&#8220;imgCol&#8221;,imgCol.first()) \/\/ \u7b2c\u4e00\u666f\u5f71\u50cf\u7684\u4fe1\u606f<br>\/\/ \/\/ compute the image total size<br>var imgSize = imgCol.size();<br>print(&#8216;imgSize&#8217;,imgSize) \/\/ 826<\/p>\n\n\n\n<p>var imgTiles = ee.FeatureCollection(imgCol.map(function(img){<br>var tmpFootprint = ee.Image(img).geometry();<br>var WRS_PATH = ee.Number(ee.Image(img).get(&#8220;WRS_PATH&#8221;));<br>var WRS_ROW = ee.Number(ee.Image(img).get(&#8220;WRS_ROW&#8221;));<br>return ee.Feature(tmpFootprint,null).set(&#8220;WRS_PATH&#8221;,WRS_PATH).set(&#8220;WRS_ROW&#8221;,WRS_ROW);<br>})).distinct([&#8220;WRS_PATH&#8221;,&#8217;WRS_ROW&#8217;]);<br>\/\/ print(&#8220;imgTiles&#8221;,imgTiles); \/\/ \u6253\u5370\u6240\u6709\u7684 imgTiles \u4fe1\u606f<br>var styling1 = {color:&#8217;red&#8217;,fillColor:&#8217;00000000&#8242;}<br>\/\/ print(&#8220;imgTiles&#8221;,imgTiles.limit(5)); \/\/ \u6253\u5370\u524d\u4e94\u4e2a<br>print(&#8220;imgTiles size&#8221;,imgTiles.size()); \/\/ 21, imgTiles \u5927\u5c0f<br>Map.addLayer(imgTiles.style(styling1), {}, &#8216;imgTiles&#8217;);<br>\/\/ \u6253\u5370\u51fa\u6240\u6709\u884c\u5217\u53f7\uff0c\u5e76\u6392\u9664\u91cd\u590d\u503c<br>\/\/ print(&#8220;imgTiles&#8221;, imgTiles.aggregate_array(&#8220;WRS_PATH&#8221;).distinct());<br>\/\/ print(&#8220;imgTiles&#8221;, imgTiles.aggregate_array(&#8220;WRS_ROW&#8221;).distinct())<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code># List \u548c ImageCollection \u914d\u5408\n## \u82e5\u5e72\u5e74\u4efd\u6700\u5c11\u4e91\u91cf\u5f71\u50cf\u7684\u5efa\u7acb\n&#91;\u4ee3\u7801](https:\/\/code.earthengine.google.com\/fe3e994f34566d2b1afa91e88196cece)<\/code><\/pre>\n\n\n\n<p>javascript<br>Imports (1 entry)<br>var AOI: Polygon, 4 vertices<\/p>\n\n\n\n<p>var roi = AOI;<\/p>\n\n\n\n<p>Map.addLayer(roi);<br>Map.centerObject(roi, 9);<\/p>\n\n\n\n<p>var startyear = 2016;<br>var endyear = 2018;<\/p>\n\n\n\n<p>var LS7 = ee.ImageCollection(&#8216;LANDSAT\/LC08\/C01\/T1_SR&#8217;)<br>.filterBounds(roi)<br>.filterDate(startyear+&#8217;-01-01&#8242;, endyear+1+&#8217;-01-01&#8242;);<\/p>\n\n\n\n<p>\/\/ Get least cloudy annual scene \/ mosaic via the cc metadata property.<br>\/\/ years = [2000, 2001, 2002]<br>var years = ee.List.sequence(startyear, endyear).getInfo();<br>print(&#8216;years&#8217;,years)<\/p>\n\n\n\n<p>var annual_least_cc = years.map(function(year){<br>\/\/ Or get mosaic of least cloudy annual scenes.<br>var annual = LS7.filterDate(year+&#8217;-01-01&#8242;, (year+1)+&#8217;-01-01&#8242;)<br>.sort(&#8216;CLOUD_COVER&#8217;, false); \/\/ mosaic puts last element on top.<br>var annual_img = ee.Image(annual.mosaic()).clip(roi);<br>Map.addLayer(annual_img.divide(10000), {bands: [&#8216;B3&#8217;, &#8216;B2&#8217;, &#8216;B1&#8217;], min: 0, max: 0.3}, &#8220;layer&#8221;+year);<\/p>\n\n\n\n<p>return annual_img;<br>})<br>annual_least_cc = ee.ImageCollection(annual_least_cc);<br>print(annual_least_cc);<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>## \u6708\u5408\u6210\u5f71\u50cf\n&#91;\u4ee3\u7801](https:\/\/code.earthengine.google.com\/c60499b4dbe5b53bcb66e3e3c1ab7407)<\/code><\/pre>\n\n\n\n<p>javascript<br>Imports (1 entry)<br>var AOI: Polygon, 4 vertices<\/p>\n\n\n\n<p>var roi = AOI;<br>\/\/show the study area<br>Map.centerObject(roi,5);<br>Map.addLayer(roi, {color: &#8220;gray&#8221;}, &#8220;roi&#8221;);<\/p>\n\n\n\n<p>var S2 = ee.ImageCollection(&#8216;COPERNICUS\/S2_SR&#8217;); \/\/S2_SR<\/p>\n\n\n\n<p>var S2SRCol = S2\/\/.filter(ee.Filter.lt(&#8216;CLOUDY_PIXEL_PERCENTAGE&#8217;,20))<br>.filterDate(&#8216;2020-03-01&#8217;, &#8216;2020-11-01&#8217;)<br>.filterBounds(roi)<\/p>\n\n\n\n<p>var monthcomposite = ee.List.sequence(0, 1*6).map(function(n) {<br>var start = ee.Date(&#8216;2020-04-01&#8217;).advance(n, &#8216;month&#8217;);<br>var end = start.advance(1, &#8216;month&#8217;);<br>return S2SRCol.filterDate(start, end).median().clip(roi);<br>}).flatten();<br>print(monthcomposite);<br>var imageCol = ee.ImageCollection.fromImages(monthcomposite);<\/p>\n\n\n\n<p>var sCol = imageCol.toList(imageCol.size());<\/p>\n\n\n\n<p>var ls = [];<\/p>\n\n\n\n<p>for (var i=0; i&lt;sCol.length().getInfo(); i++) {<\/p>\n\n\n\n<p>var imageData = ee.Image(sCol.get(i));<br>Map.addLayer(imageData, {bands:[&#8216;B11&#8242;,&#8217;B8&#8242;,&#8217;B4&#8217;],min:0,max:3000}, &#8220;timeWindow_&#8221;+i);<br>}<br>&#8220;`<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u57fa\u7840\u77e5\u8bc6 GEE = Googl&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":384,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[13],"class_list":["post-181","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-6","tag-13"],"_links":{"self":[{"href":"https:\/\/lxylp.com\/index.php?rest_route=\/wp\/v2\/posts\/181","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lxylp.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lxylp.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lxylp.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lxylp.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=181"}],"version-history":[{"count":1,"href":"https:\/\/lxylp.com\/index.php?rest_route=\/wp\/v2\/posts\/181\/revisions"}],"predecessor-version":[{"id":182,"href":"https:\/\/lxylp.com\/index.php?rest_route=\/wp\/v2\/posts\/181\/revisions\/182"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/lxylp.com\/index.php?rest_route=\/wp\/v2\/media\/384"}],"wp:attachment":[{"href":"https:\/\/lxylp.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=181"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lxylp.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=181"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lxylp.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=181"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}