Create a minimum and maximum raster from a stacked raster (series of images) in Google Engine

Question

I am trying to write a script that can output a raster file based on the highest and lowest values ​​found in the list of rasters. It is similar to what r.series does in QGIS-GRASS. How can I do this?

El script es el siguiente:

var table = table.filter(ee.Filter.eq('NOMBRE_DPT', 'CASANARE'));

var sentinel1 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-01-01', '2021-01-15')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                    .filterBounds(table);
var sentinel2 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-01-16', '2021-01-30')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                     .filterBounds(table);
var sentinel3 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-02-01', '2021-02-15')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                     .filterBounds(table);
var sentinel4 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-02-16', '2021-02-28')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                     .filterBounds(table);
                    
var sentinel5 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-03-01', '2021-03-15')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                     .filterBounds(table);
var sentinel6 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-03-16', '2021-03-31')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                     .filterBounds(table);   
var sentinel7 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-04-01', '2021-04-15')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                     .filterBounds(table); 
var sentinel8 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-04-16', '2021-04-30')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                    .filterBounds(table);  
var sentinel9 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-05-01', '2021-05-15')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                    .filterBounds(table);
var sentinel10 = ee.ImageCollection('COPERNICUS/S1_GRD')
                    .filterDate('2021-05-16', '2021-05-31')
                    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
                    .filter(ee.Filter.eq('instrumentMode', 'IW'))
                    .filter(ee.Filter.or((ee.Filter.eq('orbitProperties_pass', 'ASCENDING'), ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))))
                    .filterBounds(table);
                    
var image1 = sentinel1.select('VH').mean().rename('VH1');
var image2 = sentinel2.select('VH').mean().rename('VH2');
var image3 = sentinel3.select('VH').mean().rename('VH3');
var image4 = sentinel4.select('VH').mean().rename('VH4');
var image5 = sentinel5.select('VH').mean().rename('VH5');
var image6 = sentinel6.select('VH').mean().rename('VH6');
var image7 = sentinel7.select('VH').mean().rename('VH7');
var image8 = sentinel8.select('VH').mean().rename('VH8');
var image9 = sentinel9.select('VH').mean().rename('VH9');
var image10 = sentinel10.select('VH').mean().rename('VH10');

var stacked = image1.addBands([image2,image3,image4,image5,image6,image7,image8,image9,image10]).clip(table);
print(stacked);

var stacked_scaled = stacked.multiply(10).add(350).uint8();
var bands = ['VH9', 'VH1', 'VH4'];
var display = {bands: bands, min: 0, max: 220};
Map.addLayer(stacked_scaled, display, 'stacked');
Map.setCenter(-71.70,4.32,8);

ImageCollection.min()???????

Answer 1

The easiest way to calculate the minimum and maximum value from a series of images is to cast them into an image collection and then use a reducer to calculate the desired metric. Here is the modified version of your script that should output the desired min and max rasters.

var image1 = sentinel1.select('VH').mean();
var image2 = sentinel2.select('VH').mean();
var image3 = sentinel3.select('VH').mean();
var image4 = sentinel4.select('VH').mean();
var image5 = sentinel5.select('VH').mean();
var image6 = sentinel6.select('VH').mean();
var image7 = sentinel7.select('VH').mean();
var image8 = sentinel8.select('VH').mean();
var image9 = sentinel9.select('VH').mean();
var image10 = sentinel10.select('VH').mean();

// Create image collection from list of images
var stacked = ee.ImageCollection.fromImages([image1,image2,image3,image4,image5,image6,image7,image8,image9,image10]);
// Scale all the images
var stacked_scaled = stacked.map(function(image){
  return ee.Image(image).multiply(10).add(350).uint8();
  });

var min = stacked_scaled.min();
var max = stacked_scaled.max();

Map.addLayer(min, {}, 'min');
Map.addLayer(max, {}, 'max');