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I need help solving this GEE internal error. I am trying to reduce my script lines in GEE. So, I tried to use a single function to compute polarization indexes.

However, the console shows a warning saying: enter image description here

This is the script:

// Function to compute and add polarization indexes as bands
var addindexes = function(ima) {
  var NDPI = ima.select('VV').subtract(ima.select('VH'))
    .divide(ima.select('VV').add(ima.select('VH')));
  var NVHI = ima.select('VH').divide(ima.select('VV').add(ima.select('VH')));
  var NVVI = ima.select('VV').divide(ima.select('VV').add(ima.select('VH')));
  var VHrVV = ima.select('VH').divide(ima.select('VV'));
  var indexes = ee.List([NDPI,NVHI,NVVI,VHrVV]);
  return ima.addBands(indexes);
};

// Add index bands to image collection
var S1_indexes = allSeasons.map(addindexes);
print(S1_indexes);

1 Answer 1

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Without a full script it is a little difficult to debug, but one problem I see is that you are providing an ee.List object to the addBands method, but it requires an ee.Image object. Try using ee.Image.cat instead of ee.List like this:

// Make toy data
var allSeasons = ee.ImageCollection(
  ee.Image.constant([25, 10]).rename('VV', 'VH'));
print(allSeasons);

// Function to compute and add polarization indexes as bands
var addindexes = function(ima) {
  var VV = ima.select('VV');
  var VH = ima.select('VH');
  var NDPI = VV.subtract(VH).divide(VV.add(VH));
  var NVHI = VH.divide(VV.add(VH));
  var NVVI = VV.divide(VV.add(VH));
  var VHrVV = VH.divide(VV);
  var indexes = ee.Image.cat(NDPI, NVHI, NVVI, VHrVV)
    .rename(['NDPI', 'NVHI', 'NVVI', 'VHrVV']);
  return ima.addBands(indexes);
};

// Add index bands to image collection
var S1_indexes = allSeasons.map(addindexes);
print(S1_indexes);

Note that I added two variables (VV and VH) so that ima.select() was not repeated.

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  • Thank you very much! It worked and It's even better than I expected. Nov 14, 2019 at 13:13

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