75 lines
2.2 KiB
JavaScript
75 lines
2.2 KiB
JavaScript
/**
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* Sentinel-1 哨兵一号数据下载 —— 以下载 2023-2024 年云南省边境影像为例
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*
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* @author CVEO Team
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* @date 2025-12-18
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*
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* 1. 加载 Sentinel-1 数据
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* 2. 导出COG云优化并填补缺失值的GeoTIFF影像分块
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*/
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// 加载研究区域和影像
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// var region_name = "德宏傣族景颇族自治州"; // 瑞丽县所在
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var region_name = "保山市"; // 德宏州东侧
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var region_name_en = "baoshan";
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var region = allCites.filter(ee.Filter.eq("市", region_name));
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var yunnan = allCites.filter(ee.Filter.eq("省", "云南省"));
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var year = 2023;
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var start_date = year + "-04-09";
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var end_date = year + "-04-11";
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var region_geo = region.geometry();
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var bounds = region_geo.bounds();
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var common_filter = ee.Filter.and(
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ee.Filter.bounds(bounds),
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ee.Filter.date(start_date, end_date)
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);
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// 加载Sentinel-1 GRD数据
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var S1dataset = ee
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.ImageCollection("COPERNICUS/S1_GRD")
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.filter(common_filter)
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.filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV'))
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.filter(ee.Filter.eq('instrumentMode', 'IW'))
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.select('VV');
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print(start_date + " - " + end_date + " S1dataset", S1dataset);
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var s1_img = ee.Image(S1dataset.median());
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var s1_vis = {
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min: -25,
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max: 5
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};
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var styling1 = {
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color: "blue",
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fillColor: "00000000",
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};
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var styling2 = {
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color: "red",
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fillColor: "00000000",
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};
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Map.centerObject(region, 7);
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Map.addLayer(s1_img, s1_vis, start_date + " Sentinel-1 GRD");
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Map.addLayer(yunnan.style(styling2), {}, "云南省");
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Map.addLayer(region.style(styling1), {}, region_name);
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// 导出 Sentinel-1 影像
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// 明确设置数据类型为Float32, 否则默认类型为Float64, 会占用更多内存
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// 并对缺失值进行填充, 否则默认为nan不便于后续本地处理
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var processed_img = S1dataset.first().toFloat().unmask(-9999.0);
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Export.image.toDrive({
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image: processed_img,
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description: "S1A_IW_GRDH_1SDV_" + start_date,
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folder: "Sentinel-1",
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// region: region,
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scale: 10,
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maxPixels: 1e13, // GEE 最多支持 1e8 像素, 当超过时会自动分块
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fileFormat: "GeoTIFF",
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// 导出COG云优化的GeoTIFF影像, 并明确设置缺失值为-9999.0
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formatOptions: {
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cloudOptimized: true,
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noData: -9999.0,
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},
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});
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