I have a series of buffers stored in a feature collection. Some but not all of the buffer polygons overlap. I need to dissolve the polygons in a way that Google Earth Engine still recognizes each as a separate polygon with a unique ID (its own feature in a feature collection) so that I can then determine the polygon that each of my sample points falls into.

The user support I've found on this topic uses the union function like this:

var buffsSample=buffers.union();

This creates a feature collection of one large polygon (one feature). I want a feature collection where each stand-alone polygon (some of them dissolved, some not) is its own unique feature with an ID.

UPDATE: I found that I could create a multipolygon with separate coordinates for each polygon as follows:

var buffsSample=buffers.geometry().dissolve();

The problem is that this is a multipolygon and not a feature collection. When I took this multipolygon and converted it to a feature collection as follows:

var buffsFeature = ee.FeatureCollection(buffsSample)

I end up with the exact feature collection I would have gotten using '''union()''' (only one feature, whereas I want each polygon to be a feature).

Please let me know if you have suggestions for converting the multipolygon into a feature collection where each buffer is its own feature. Or if you have an alternative suggestion for dissolving polygons within a feature collection and returning a feature collection where each polygon is its own feature.

Code here.


I think I found a solution based on this past post. Full code:

//Create demo data//////////////////////////////////////

var region = ee.Geometry.Rectangle(-120, 34.669, -99.536, 50.064);

// Create 10 random points in the region.
var randomPoints = ee.FeatureCollection.randomPoints(region, 1000);

//Produce 10 km buffers, these are the polygons we want to dissolve
var bufferPoly = function(feature) {
  return feature.buffer(10000); 

var buffers = randomPoints.map(bufferPoly);
Map.addLayer(buffers, {}, 'buffers');
//print(buffers.limit(10), "Overlapping buffers"); //Each buffer has its own ID but some overlap!

//Buffers: dissolve and transform to FC so that we can identify each
//tile's buffer ID

var buffsGeoDissolve =buffers.geometry().dissolve();
print(buffsGeoDissolve, "Dissolve using geometry().dissolve()"); //Multipolygon!
Map.addLayer(buffsGeoDissolve, {}, 'Dissolve using geometry().dissolve()');

var fc = ee.FeatureCollection([

var multiGeomExplodeList = fc.toList(fc.size()).map(function(feature) {
  var geomList = ee.Feature(feature).geometry().geometries();
  var featureList = geomList.map(function(geom) {
    return ee.Feature(ee.Geometry(geom));
  return featureList;

var buffDissolveFC = ee.FeatureCollection(multiGeomExplodeList);

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