Wallpaper_Maker

/**** Start of imports. If edited, may not auto-convert in the playground. ****/
var Screen1992x1121Ratio16x9 = /* color: #e2e2e2 */ee.Geometry.Polygon(
        [[[-3.3220212403222416, 51.5531770278373],
          [-3.3220212403222416, 51.42790920999614],
          [-2.964278930751929, 51.42790920999614],
          [-2.964278930751929, 51.5531770278373]]], null, false);
/***** End of imports. If edited, may not auto-convert in the playground. *****/
// #### SCRIPT START ####
// ##################
// ### PARAMETERS ###
// ##################
//     These apply the parameters to all imagery, to stop redundant data entry
// ## CLOUD ##  
//    Format: %'0-000'. Numbers only without quotes
// # MIN CLOUD PERCENT #
var MIN_CLOUD_PERCENT = 10;
/*   Deals with TILES - Tiles with >X% of cloud by area are filtered out
*    This reduces the frequency of available images, by removing ones that might not be useful for further analysis
*    Set to 100 to not filter at all, and put the heavy lifting onto Masking cloud probability instead
*/
// # MAX CLOUD PROBABILITY #
var MAX_CLOUD_PROB = 100;
/*   Deals with clouds IN-IMAGE - Areas that have >Y% probability of being a cloud are masked out within the tile
*    This maximises frequency of images, but at the cost of requiring more processing to analyse every available image
*    Lower numbers increases the range of criteria that match 'clouds' to mask 
*    E.g. 100% will miss cloud edges & cirrus, 10% will start masking out roofing and water bodies. 20 is a compromise 
*/
// ## START/END DATE ## 
//    Format: 'YYYY-MM-DD', include the quotes. This for the time series range.
var START_DATE = '2018-01-01';
var END_DATE = '2025-01-01';
// ## BOUNDS ## 
var BOUNDS = Screen1992x1121Ratio16x9;
//    Format: Either be a drawn geometry shape within GEE, or an imported SHP file
//    See: https://developers.google.com/earth-engine/guides/table_upload#upload-a-shapefile

// ## ZOOM ## 
//    Based on GEE's 1-24 level system. Larger number = More Zoom
var ZOOM = 11;
// ## PREVIEW DATES ## 
var FRST_PRVW_DATE = '2023-01-01';
var LAST_PRVW_DATE = '2025-01-01';
/*    For displaying a particular date on the map, as otherwise the Layers don't match
*     To display a particular image on a particular time, select the day before and after it
*     i.e. "2022-03-31" requires the filter to be set between 03-30 and 04-01
*    This ONLY applies to displayed imagery on the map - The entire time series data is still exportable
*/
// PARAMETERS END - You don't need to change anything below this line to make the script function

// ############
// ### MISC ###
// ############
// Prints out the Parameters set
print('Running parameters set on Lines 10-50:');
print('Filtering available Sentinel 2 imagery between ' + START_DATE + ' & ' + END_DATE + '.');
print(' Tiles are filtered by '+ MIN_CLOUD_PERCENT + '%, and pixels matching >' + MAX_CLOUD_PROB + '% of being clouds, are masked' );
print('Map will display imagery from between ' + FRST_PRVW_DATE + ' & ' + LAST_PRVW_DATE + '.');
// Centre based on the Geometry (Region of Interest, Zoom Level)
Map.centerObject(BOUNDS, ZOOM, print('Map centered on Region of Interest'));
// Sets the default Map to Terrain mode (Roadmap overlain with hillsahde) 
Map.setOptions("TERRAIN");

// #################################
// ### PALETTES & VISUALISATIONS ###
// #################################
// ## EEPALETTES ##
/*    Required for most layer visualisations
*     See https://github.com/gee-community/ee-palettes for more information
*     IF IT FAILS TO LOAD the PALETTES, LOAD THIS URL FIRST, THEN REFRESH THE PAGE: 
*     (https://code.earthengine.google.com/?accept_repo=users/gena/packages)
*/
var palettes = require('users/gena/packages:palettes');
// NDWI palette 
var NDWIPalette = palettes.cmocean.Ice[7].reverse();
// NDVI palette
var NDVIPalette = palettes.colorbrewer.RdYlGn[10];
// ## VISUALISATIONS ##
// # UNMODIFIABLE #
//   Don't change these    
// Truecolour (R-G-B) Visualisation (for Sentinel 2 Imagery only)
var RGBVis = {
  min: 0,
  max: 0.3,
  bands: ['B4', 'B3', 'B2'],
};
// Falsecolour (IR-G-B) Visualisation (for S2 - Not in use, but available)
var NIRVis = {
  min: 0,
  max: 0.5,
  bands: ['B8', 'B3', 'B2'],
};
// NDWI Visualisation
var NDWIVis = {
  min: -1,
  max: 1,
  bands: ['NDWI'],
  palette: NDWIPalette
};
// NDVI Visualisation
var NDVIVis = {
  min: -1,
  max: 1,
  bands: ['NDVI'],
  palette: NDVIPalette
};

// #####################
// ### CLOUD MASKING ###
// #####################
/*     Sentinel 2 Cloud Masking Function using the QA_60m Cloud Mask Band
 *     @param {ee.Image} image Sentinel-2 image
 *     @return {ee.Image} cloud masked Sentinel-2 image
 *     (Applies to L1C and L2A Imagery)
 */
function maskS2clouds(image) {
  var qa = image.select('QA60');
  // Bits 10 and 11 are clouds and cirrus, respectively.
  var cloudBitMask = 1 << 10;
  var cirrusBitMask = 1 << 11;
  // Both flags should be set to zero, indicating clear conditions.
  var mask = qa.bitwiseAnd(cloudBitMask).eq(0).and(qa.bitwiseAnd(cirrusBitMask).eq(0));
   // Applies the cloud masking conditions to the IC, and adds the date of acquisition into each image for easy timeseries organising later
   return image.updateMask(mask).divide(10000).copyProperties(image, ["system:time_start"]);
}
print('Sentinel 2 Cloud Mask Function Complete');

// #########################
// ### IMAGE COLLECTIONS ###
// #########################
//Load and Map L1C/L2A imagery with the filter parameters applied
                 /*
                  *  Load Sentinel-2 'Harmonized' Bottom Of Atomsphere (L2A) data
                  *  Dataset details: https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_S2_SR_HARMONIZED
                  *  HARMONIZED makes sure scenes after 25 January 2022 have the same DN ranges as older L2A scenes.
                  *  Data is limited to 2017-03-28 onwards. (i.e. older data has to come from non-harmonised datasets)
                  */
var S2_L2A = ee.ImageCollection('COPERNICUS/S2_SR_HARMONIZED')
                  .select('B2','B3', 'B4', 'B8','B8A','B9', 'QA60')
                  // Filter by Date Period (YYYY-MM-DD)
                  .filterDate(START_DATE, END_DATE)
                  /* 
                  *  Pre-filter to get less cloudy granules
                  *  'Default' is aiming for 10% cloud
                  *  Dependent on availability of cloud-free imagery in the time period set
                  *  Longer periods will take longer to load
                  */
                  .filter(ee.Filter.lte('CLOUDY_PIXEL_PERCENTAGE', MIN_CLOUD_PERCENT))
                  // Select only image tiles that fall within the Geometry (Region of Interest) to reduce processing time
                  .filterBounds(BOUNDS)
                  // Applies the S2 Cloud Masking Function to each image in the IC
                  .map(maskS2clouds)
                  // Clips each image in the IC by the Bounds to reduce processing time further
                  .map(function(image) {
                    return image.clip(BOUNDS);
                  });

// ## ALTERNATE L2A MASKING ##
var S2_CloudProb = ee.ImageCollection('COPERNICUS/S2_CLOUD_PROBABILITY');
function maskClouds(image) {
  var clouds = ee.Image(image.get('cloud_mask')).select('probability');
  var isNotCloud = clouds.lt(MAX_CLOUD_PROB);
  return image.updateMask(isNotCloud);//.divide(10000).copyProperties(image, ["system:time_start"]);
}
// The masks for the 10m bands sometimes do not exclude bad data at
// scene edges, so this applies masks from the 20m and 60m bands as well.
function maskEdges(s2_image) {
  return s2_image.updateMask(
      s2_image.select('B8A').mask().updateMask(s2_image.select('B9').mask()));
}
// Filter input collections by desired data range and region.
var criteria = ee.Filter.and(
    ee.Filter.bounds(BOUNDS), ee.Filter.date(START_DATE, END_DATE));
S2_L2A = S2_L2A.filter(criteria).map(maskEdges);
S2_CloudProb = S2_CloudProb.filter(criteria);
// Join S2 SR with cloud probability dataset to add cloud mask.
var S2SRWithCloudMask = ee.Join.saveFirst('cloud_mask').apply({
  primary: S2_L2A,
  secondary: S2_CloudProb,
  condition:
      ee.Filter.equals({leftField: 'system:index', rightField: 'system:index'})
});
var S2CloudMasked =
    ee.ImageCollection(S2SRWithCloudMask).map(maskClouds);
print('Time, Date, Bounding, Clipping, and Cloud Tile Filtering parameters set for Imagery');

// Map Collections to View
print('L2A Collection',S2_L2A);
print('L2A Collection Cloud Masked',S2CloudMasked);
Map.addLayer(S2CloudMasked.filterDate(FRST_PRVW_DATE, LAST_PRVW_DATE), RGBVis,'L2A ClearSkies',false);
Map.addLayer(S2CloudMasked.filterDate(FRST_PRVW_DATE, LAST_PRVW_DATE), NIRVis,'L2A Aerochrome',false);

// ###############
// ### BUTTONS ###
// ###############
// Create a panel for Buttons with vertical flow layout.
var ButtonPanel = ui.Panel({
  layout: ui.Panel.Layout.flow('vertical'),
  style: {width: '10%'}
});
// ## EXPORT LAYERS BUTTON ##
ButtonPanel.add(ui.Button({  
  label: 'Export Image',
  style: {stretch: 'horizontal', Color: '#1e90ff'},
  onClick: function() {
//    # PROPERTY EXTRACTION # 
//      For naming exported files by the system:index (identifier)
// Filtering the timeseries range to just a particular day (i.e. 2022-03-31)
var S2_L2A_Filt = S2_L2A.filterDate(FRST_PRVW_DATE, LAST_PRVW_DATE);
// Pulls out the System:Index Property of every element in the Filtered IC, puts it in a dictionary, and inserts it into the Properties 
var SystemIndex = S2_L2A_Filt.map(function (image) {
  return image.set('SysIndex', image.toDictionary(['system:index']));
});
// Aggregates the Dictionary into an Array (List)
var list = SystemIndex.aggregate_array('SysIndex');
// Gets only the first Element of the List
var list_1st = list.get(0);
//    # MOSAICING #
//    Mosaics the current filterered view into a single image, for exporting
var S2_Median = S2CloudMasked.reduce(ee.Reducer.median()).set(list_1st);
print(S2_Median);
var S2_L2A_Mosaic = S2_Median
                    .select(['B2_median','B3_median','B4_median','B8_median','B8A_median','B9_median','QA60_median'],
                            ['B2','B3','B4','B8','B8A','B9','QA60']);
//var S2_L2A_Mosaic = S2CloudMasked.mosaic().set(list_1st);
// Display the Layers that are to be exported (for final confirmation of download)
Map.addLayer(S2_L2A_Mosaic, RGBVis, 'L2A Export');
Map.addLayer(S2_L2A_Mosaic, NIRVis, 'L2A Aerochrome Export');
print('L2A Mosaic',S2_L2A_Mosaic);

//    # PROPERTY APPLICATION #
// Gets the System:Index of the Mosaic as a String
var index = S2_L2A_Mosaic.get('system:index');
/* Sentinel 2 Imagery follows this naming convention:
*  START TIME:'(YYYYMMDD)T(HHMMSS)_' + END TIME:'(YYYYMMDD)T(HHMMSS)_' + UTM MGRS ID: 'T00ABC'
*  So slicing it to the first 13 characters gives you the swath start time, to the minute
*  This is extracted using getInfo() which can then be put into the image name.
*  Only has to be done on one of the Mosaic layers, as the system:index will be the same for all of them
*/
var index = index.getInfo().slice(0,13);
//    # EXPORTS #   
Export.image.toDrive({
    image: S2_L2A_Mosaic.visualize(RGBVis), // Sets the image to keep the current Visualisation parameters
    region: BOUNDS, // The area of interest
    description: 'LOCATION_' + index, // Sets the name of the image(s) with the date
    folder: 'GEE_Wallpapers', // The destination folder for the imagery in your Account's Google Drive
    scale: '20', // scale in m/px. 'Nominal' returns requested image AT TRUE SCALE
    crs: 'EPSG:3857', // CRS - This is the standard GEE Web Mercator projection, WGS84.
    maxPixels: 1e13, // Max Pixel amount - always required as the default limit is very small
    fileFormat: 'GeoTIFF'
});
print('Please check the Tasks tab to confirm Export');
  }
}));
// Adds the Button Panel to the Map
ui.root.add(ButtonPanel);