//__author__ = "Petr Sevcik"
//__copyright__ = "Petr Sevcik as S.cartography"
//__credits__ = ["Petr Sevcik"]
//__license__ = "GPL"
//__version__ = "1.0"
//__maintainer__ = "Petr Sevcik"
//__email__ = "sevcik.cartography@gmail.com"
//__status__ = "Alpha"


//Select all Sentinel-1 products from of 2016 and 2017, HH and HV polarization
var collection_HH = ee.ImageCollection('COPERNICUS/S1_GRD')
.filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'HH'))
.select('HH')
.filterDate('2016-10-01', '2017-09-30')
;


var collection_HV = ee.ImageCollection('COPERNICUS/S1_GRD')
.filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'HV'))
.select('HV')
.filterDate('2016-10-01', '2017-09-30')
;


//HH and HV polarization imagery
var HV = ee.ImageCollection(collection_HV.reduce(ee.Reducer.intervalMean(65, 70))).mosaic();
var HH = ee.ImageCollection(collection_HH.reduce(ee.Reducer.intervalMean(70, 75))).mosaic();


//Generate the blue component as a non-absolute difference
var db_difference = HH.subtract(HV)

//Build RGB Composites for better understanding
var RGB = ee.Image.cat([
  HH,
  HV,
  db_difference
  ]);


// Display map
// Default location
var pt = ee.Geometry.Point(0.0,0.0);
Map.centerObject(pt, 3);

//Add the mosaic layer as a RGB composite with RGB values streching from 'min' to 'max' of the decibel values
Map.addLayer(RGB, {min: [-20, -25, 0], max: [0, -5, 15]}, 'SAR HH HV RGB World 2016-2017');


// Export the image, specifying scale and region.
Export.image.toDrive({
  image: RGB,
  description: 'ARCTIC Sentinel-1 HH HV RGB 2016-2017',
  scale: 2500,
  region: geometry,
});