Google Earth Engine – Raster to Vector Conversion in Google Earth Engine

google-earth-enginevectorization

I would like to convert a raster image into vector. My image is referenced to a specific zone (vect).
I'm working with Hansen dataset and in particularly the layer 'lossyear'. Raster image is from a different polygon in a specific year (for example 2007) and I obtain it by the function ReduceResolution. The value of different pixel that constitute the image are float number. The code is:

var loss_2007_vt = loss_2007_filtered_res.reduceToVectors({ reducer: ee.Reducer.mean(), geometry: vect, crs: collection.projection(), scale:500, geometryType:'polygon', });

I received this error message: "FeatureCollection (Error)
Image.reduceToVectors: Need 1+1 bands for , image has 1".

Best Answer

Try not specifying the reducer. I think it's looking for additional bands to reduce (i.e. get the mean for a homogeneous region and set it as a property of the output feature) and not finding any.

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I advise you could use Wintopo, sir :)

Converting Raster to Vector in Google Earth Engine – How to Guide

One giant Multipolygon per class isn't going to scale very well, but it's not hard to produce that.

var geometry = ee.Geometry.Rectangle([29.1796875, 32.02670629333615, 32.607421875, 29.993002284551075]);
var landcover = ee.Image('MCD12Q1/MCD12Q1_005_2001_01_01').select('Land_Cover_Type_1');

// Run reduceToVectors per class by masking all other classes.
var classes = ee.List([0, 1, 2, 3, 4, 5, 6, 7, 8])
  .map(function(n) {
    var classImage = landcover.eq(ee.Number(n));
    var vectors = classImage.updateMask(classImage)
      .reduceToVectors({
        reducer: ee.Reducer.countEvery(), 
        geometry: geometry, 
        scale: 30,
        maxPixels: 1e8})
      .geometry();
    return ee.Feature(vectors, {"class": n});
  });
var result = ee.FeatureCollection(classes);
Map.addLayer(result);

But you'd be better off with 1 feature per polygon. In both cases, each feature will have a "label" identifying the class.

var geometry = ee.Geometry.Rectangle([29.1796875, 32.02670629333615, 32.607421875, 29.993002284551075]);
var landcover = ee.Image('MCD12Q1/MCD12Q1_005_2001_01_01').select('Land_Cover_Type_1');

var classes = landcover.reduceToVectors({
  reducer: ee.Reducer.countEvery(), 
  geometry: geometry, 
  scale: 30,
  maxPixels: 1e8
});
var result = ee.FeatureCollection(classes);
Map.addLayer(result);

Best Answer

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