Clasificación del NDVI mediante el motor de Google Earth

Question

Quiero clasificar mi raster NDVI utilizando datos de entrenamiento en Google Earth Engine. Para ello estoy utilizando el siguiente código. Pero está devolviendo algún error como ndvi no es una banda utilizable. Por favor, ayuda en esto

// Cloud Masking function
function maskS2clouds(image) {
  var qa = image.select('QA60');

  // Bits 10 and 11 are clouds and cirrus, respectively.
  var cloudBitMask = ee.Number(2).pow(10).int();
  var cirrusBitMask = ee.Number(2).pow(11).int();

  // Both flags should be set to zero, indicating clear conditions
  var mask = qa.bitwiseAnd(cloudBitMask).eq(0).and(
             qa.bitwiseAnd(cirrusBitMask).eq(0));

  // Return the masked and scaled data.
  return image.updateMask(mask).divide(10000);
}

// AOI of Study Area
var boundary = ee.FeatureCollection('ft:1rbhNtC1TqDBvY9Rt2BZR-DjhpIPuC3nU5kmz49WW');//Jorhat Boundary
//var boundary = ee.FeatureCollection('ft:1ABffZYEE4XhMTOXsoSfWENKXBK2fQfOrdMplEaVo');//Midnapur Boundary

// Import of Images (Sentinel 2 multispectral)
var image = ee.ImageCollection(sent2img
  .filterDate("2017-12-01","2018-01-30")
  .filterBounds(boundary)
  .map(maskS2clouds)
  .sort("CLOUD_COVERAGE_ASSESSMENT")
  .median()
);

// Preprocessing 
var mosaic = image.mosaic()
var clip = mosaic.clip(boundary);
print(clip);

// FCC creation and visualisation of AOI     
Map.addLayer(clip, {bands: ['B8','B4','B3'], min: 0, max: 0.3},'clip');

// NDVI  calculation
var ndvi = clip.expression(
    ' ((NIR - RED) / (NIR + RED))', {
      'NIR': clip.select('B8'),
      'RED': clip.select('B4'),
}).rename('nd');

print(ndvi);

// Colour Palette
var palette = ['FFFFFF', 'CE7E45', 'DF923D', 'F1B555', 'FCD163', '99B718',
               '74A901', '66A000', '529400', '3E8601', '207401', '056201',
               '004C00', '023B01', '012E01', '011D01', '011301'];

// Map display
Map.addLayer(ndvi, {min:0, max:1, palette: palette},"NDVI");

// Training Classes 
var newfc = wb.merge(plantation)
              .merge(agriland1)
              .merge(agriland2)
              .merge(habitation)
              .merge(sandyarea)
              .merge(deepplantation);
var bands = ['nd'];
var training = clip.select(bands).sampleRegions({
  collection: newfc, 
  properties: ['class'], 
  scale: 20,
  geometries:true
});

var classifier = ee.Classifier.cart().train({
  features: training, 
  classProperty: 'class', 
  inputProperties: bands
});

var classified = clip.select(bands).classify(classifier);

Map.addLayer(
  classified, 
  {min: 1, max: 7, palette: ['#0d1898', '#ff0841', '#138b11','#fff81c','#154c17','#529400','#F1B555']},
  'classification');

Answer 1

Has olvidado añadir ndvi banda a la imagen:

Haz esto:

// -----------  NDVI  calculation

var ndvi = clip.expression(
    ' ((NIR - RED) / (NIR + RED))', {
      'NIR': clip.select('B8'),
      'RED': clip.select('B4'),
}).rename('nd');

clip = clip.addBands(ndvi)

https://code.earthengine.google.co.in/64019c5b9fe1023f8633d182d2388d91