Google Earth Engine（GEE）分幅显示图

Google Earth Engine（GEE）分幅显示图

今天来分享下在GEE分幅显示两张不同的图，以NDVI为例，目标是可以在界面显示不同年份的NDVI，进行对比分析。 实现代码如下：

//选取银川市的部分区域var roi = ee.Geometry.Polygon( [[[106.08593436846968, 38.61243259416587], [106.08593436846968, 38.35658787595946], [106.56589957843062, 38.35658787595946], [106.56589957843062, 38.61243259416587]]], null, false);function controlPanel1(){ var Title = ui.Label({value: 'NDVI',style: {fontWeight: 'bold', fontSize: '16px'}}); var Year_selector = ui.Select({ items: [ {label: '2013', value: 2013}, {label: '2014', value: 2014}, {label: '2015', value: 2015}, {label: '2016', value: 2016}, {label: '2017', value: 2017}, {label: '2018', value: 2018}, {label: '2019', value: 2019}, {label: '2020', value: 2020}, {label: '2021', value: 2021}, ],style:{width: '150px'} }).setPlaceholder('Select year...'); var runButton = ui.Button({label: 'Run', style: {width: '150px'}}); runButton.onClick(function (){ var start_date = Year_selector.getValue() + '-01-01'; var end_date = Year_selector.getValue() + '-12-31'; var L8 = ee.ImageCollection('LANDSAT/LC08/C01/T1_SR') .filterBounds(roi) .filterDate(start_date, end_date) .filterMetadata('CLOUD_COVER_LAND', 'less_than', 5) .median(); L8 = L8.clip(roi); var nir = L8.select('B5'); var red = L8.select('B4'); var ndvi = nir.subtract(red).divide(nir.add(red)).rename('NDVI'); var ndviParams = {min: -1, max: 1, palette: ['blue', 'white', 'green']}; map1.addLayer(ndvi, ndviParams, Year_selector.getValue() +' NDVI image'); }); var panel = ui.Panel({ widgets: [Title, Year_selector, runButton], layout: ui.Panel.Layout.flow('vertical'), style:{maxHeight: '90%'} }); panel.style().set('position', 'top-left'); return panel;}function controlPanel2(){ var Title = ui.Label({value: 'NDVI',style: {fontWeight: 'bold', fontSize: '16px'}}); var Year_selector = ui.Select({ items: [ {label: '2013', value: 2013}, {label: '2014', value: 2014}, {label: '2015', value: 2015}, {label: '2016', value: 2016}, {label: '2017', value: 2017}, {label: '2018', value: 2018}, {label: '2019', value: 2019}, {label: '2020', value: 2020}, {label: '2021', value: 2021}, ],style:{width: '150px'} }).setPlaceholder('Select year...'); var runButton = ui.Button({label: 'Run', style: {width: '150px'}}); runButton.onClick(function (){ var start_date = Year_selector.getValue() + '-01-01'; var end_date = Year_selector.getValue() + '-12-31'; var L8 = ee.ImageCollection('LANDSAT/LC08/C01/T1_SR') .filterBounds(roi) .filterDate(start_date, end_date) .filterMetadata('CLOUD_COVER_LAND', 'less_than', 5) .median(); L8 = L8.clip(roi); var nir = L8.select('B5'); var red = L8.select('B4'); var ndvi = nir.subtract(red).divide(nir.add(red)).rename('NDVI'); var ndviParams = {min: -1, max: 1, palette: ['blue', 'white', 'green']}; map2.addLayer(ndvi, ndviParams, Year_selector.getValue() +' NDVI image'); }); var panel = ui.Panel({ widgets: [Title, Year_selector, runButton], layout: ui.Panel.Layout.flow('vertical'), style:{maxHeight: '90%'} }); panel.style().set('position', 'top-left'); return panel;}var map1 = ui.Map();var map2 = ui.Map();map1.add(controlPanel1());map2.add(controlPanel2());var linker = ui.Map.Linker([map1, map2]);//经纬度map1.setCenter(106.328, 38.415, 10);map1.setControlVisibility({zoomControl: false, fullscreenControl: false});map2.setControlVisibility({zoomControl: false, fullscreenControl: false});var mapPanel = ui.Panel([ui.Panel(map1, null, {stretch:'both'}),ui.Panel(map2, null, {stretch:'both'})], ui.Panel.Layout.Flow('horizontal'), {stretch:'both'});ui.root.widgets().reset([mapPanel]);ui.root.setLayout(ui.Panel.Layout.Flow('vertical'));

运行之后显示如下界面：

这样不同年份的NDVI就可以显示出来了

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