GEE学习总结（9）——像元二分法计算月度植被覆盖度(MODIS)

像元二分法计算植被覆盖度

通过MODIS的NDVI数据集MOD13Q1和像元二分法计算植被覆盖度

var multi_NDVI = ee.ImageCollection('MODIS/006/MOD13Q1').filterDate('2015-06-01', '2016-09-01').select('NDVI').max().divide(10000).clip(geometry);var ndviVis = {min: 0.0,max: 1,palette: ['FFFFFF', 'CE7E45', 'DF923D', 'F1B555', 'FCD163', '99B718', '74A901','66A000', '529400', '3E8601', '207401', '056201', '004C00', '023B01','012E01', '011D01', '011301'],
};//
Map.centerObject(geometry);//统计影像中对应分位数的值
var num = multi_NDVI.reduceRegion({reducer:ee.Reducer.percentile([5,95]),geometry:geometry,scale:250,maxPixels:1e13
});
var min = ee.Number(num.get("NDVI_p5"));
var max = ee.Number(num.get("NDVI_p95"));
print(min)
print(max)//根据统计值通过像元二分法计算植被覆盖度
var NDVI = ee.ImageCollection('MODIS/006/MOD13Q1').filterDate('2015-06-01', '2016-07-01').select('NDVI').max().divide(10000).clip(geometry);var greaterPart = NDVI.gt(max);
var lessPart    = NDVI.lt(min);
var middlePart  = ee.Image(1).subtract(greaterPart).subtract(lessPart);//计算FVC
var tempf1= NDVI.subtract(min).divide(max.subtract(min));var FVC = ee.Image(1).multiply(greaterPart).add(ee.Image(0).multiply(lessPart)).add(tempf1.multiply(middlePart));Map.addLayer(FVC, ndviVis, 'FVC');