[GIS] Combining multiple bands from different image collection into one collection

google-earth-engine

I did some calculations on variety of image collections and have generated products and saved them in variables, say a, b and c. Now I want to combine all these products (All one bands) into a multiband image collection.

What function should i use?
I tried with:

a.combine(b).combine(c)
a.merge(b).merge(c)
a.add(b).add(c)

But, these functions are not working.

Best Answer

Assuming you made a unique name for each band, and that you want to obtain one image with 3 bands (one for a, one for b and one for c) you have to addBands, like this:

var a = ee.Image(1).rename('one') // product one
var b = ee.Image(2).rename('two')
var c = ee.Image(3).rename('three')

var final = a.addBands([b, c])

link: https://code.earthengine.google.com/5c3ceef589fc8cbe6036f8f2ef22f2ca

Related Solutions

[GIS] Merging two image collection into one with two bands (LST and NDVI )

You should show more effort and paste some code, what you have tried. But anyhow, I think this is what you want:

// Collections
var mod1 = ee.ImageCollection("MODIS/006/MOD11A2");
var mod2 = ee.ImageCollection("MODIS/006/MOD13Q1");

// Some dates to filter
var d1 = ee.Date.fromYMD(2017,1,1)
var d2 = ee.Date.fromYMD(2017,3,1)

// filter collections and select needed bands
mod1 = mod1.filterDate(d1, d2).select('QC_Day')
mod2 = mod2.filterDate(d1, d2).select('NDVI')

// Use an equals filter to define how the collections match.
var filter = ee.Filter.equals({
  leftField: 'system:index',
  rightField: 'system:index'
});

// Create the join.
var simpleJoin = ee.Join.simple();

// Applt join
var mod1join = ee.ImageCollection(simpleJoin.apply(mod1, mod2, filter))
var mod2join = ee.ImageCollection(simpleJoin.apply(mod2, mod1, filter))

print('Joined', mod1join, mod2join)

var final_col = mod1join.map(function(img){

  // Create a collection with 1 image
  var temp = ee.ImageCollection(ee.List([img]));

  // Apply join to collection 2
  // Resulting collection will have 1 image with exact same date as img
  var join = simpleJoin.apply(mod2join, temp, filter);

  // Get resulting image
  var i2 = ee.Image(join.first())

  return img.addBands(i2)
})

print(final_col)

Google Earth Engine – Access Image from Image Collection

For Earth Engine the elements inside an ImageCollection are Image but inside a List are just Element, so the system doesn't know it is an Image what you are getting from it. You can read about it here.

To solve this you just have to "cast" it:

var img1 = ee.Image(listOfImages.get(0));

Best Answer

Related Solutions

[GIS] Merging two image collection into one with two bands (LST and NDVI )

Google Earth Engine – Access Image from Image Collection

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