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I'm stuck with an issue in google earth engine.

I'm working with MODIS Burned Area Monthly Global 500m, for a certain polygon area:

var MOD = ee.ImageCollection('MODIS/006/MCD64A1');
var MOD1 = MOD.filterDate('2005-06-21', '2005-09-31');
var MODlim1 = MOD.map(function(img) {return img.clip(lim)})

The problem is the image collection has three images (one for each month), and I need to convert this into a single image, which contains the burned area for three images in only one. Anyone knows what function can be helpful in this situation? I need to repeat this for every year (until 2018), so with a single image, it would be easier to analyze the data.

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  • 1
    Are you planning to combine the data somehow? or you want just a 3 bands image? Sep 12, 2018 at 16:51
  • i want the three images that compose the image collection (one for each month), converts into one image that contains the data for the three (summary: three becoming one)
    – Vann
    Sep 12, 2018 at 23:46
  • Ok, but still not answering. You need one value per pixel? or 3 values per pixel? have you worked with raster images before? Sep 13, 2018 at 1:17
  • one value per pixel. yes I have (ENVI, ARCGIS, QGIS, etc).. I thought I've answered your question. no need to be so condescending
    – Vann
    Sep 13, 2018 at 2:49
  • Sorry, I am just trying to help. The problem here is that you have 3 values (one for each month) and you want just 1 value. Assuming that your interest is in the burnDate band of MCD64A1, what will be the only value for those 3 months? the latest date? Sep 13, 2018 at 3:29

1 Answer 1

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// UPDATE: The easiest way is now toBands().
var merged = MOD1.toBands();

// For completeness, this is the iterate() way:
var mergeBands = function(image, previous) {
  return ee.Image(previous).addBands(image);
};

var merged = MOD1.iterate(mergeBands, ee.Image([]));
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    Great! everyday you learn something new =) I didn't know that using ee.Image([]) (an image with no bands) would make the loop start from the first image of the collection. Splitting the collection was a pain. Thanks! Sep 15, 2018 at 18:12
  • 1
    Some explanation about the code would be helpful. Sep 16, 2018 at 4:56
  • 2
    Learn more from the iterate() docs: the user guide and/or the API reference. Sep 17, 2018 at 3:07
  • I also obtained the result using: var merged = MOD1.iterate(mergeBands, MOD1.first());
    – shahryar
    Apr 12, 2020 at 20:31
  • Really helpful answer, thanks!
    – Waleed93
    Jul 2, 2020 at 8:29

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