convert_raster_to_vector.py

import ee 
from ee_plugin import Map 

# Load a Japan boundary from the Large Scale International Boundary dataset.
japan = ee.FeatureCollection('USDOS/LSIB_SIMPLE/2017') \
  .filter(ee.Filter.eq('country_na', 'Japan'))

# Load a 2012 nightlights image, clipped to the Japan border.
nl2012 = ee.Image('NOAA/DMSP-OLS/NIGHTTIME_LIGHTS/F182012') \
  .select('stable_lights') \
  .clipToCollection(japan)

# Define arbitrary thresholds on the 6-bit nightlights image.
zones = nl2012.gt(30).add(nl2012.gt(55)).add(nl2012.gt(62))
zones = zones.updateMask(zones.neq(0))

# Convert the zones of the thresholded nightlights to vectors.
vectors = zones.addBands(nl2012).reduceToVectors(**{
  'geometry': japan,
  'crs': nl2012.projection(),
  'scale': 1000,
  'geometryType': 'polygon',
  'eightConnected': False,
  'labelProperty': 'zone',
  'reducer': ee.Reducer.mean()
})

# Display the thresholds.
Map.setCenter(139.6225, 35.712, 9)
Map.addLayer(zones, {'min': 1, 'max': 3, 'palette': ['0000FF', '00FF00', 'FF0000']}, 'raster')

# Make a display image for the vectors, add it to the map.
display = ee.Image(0).updateMask(0).paint(vectors, '000000', 3)
Map.addLayer(display, {'palette': '000000'}, 'vectors')