3_visualization

/**** Start of imports. If edited, may not auto-convert in the playground. ****/
var GSW = ee.Image("JRC/GSW1_3/GlobalSurfaceWater"),
    v10_1_0609 = ee.ImageCollection("projects/sites-project/condition_monitoring/products_v10-1_by_state_0601-0901_1x1"),
    v10_1_0510 = ee.ImageCollection("projects/sites-project/condition_monitoring/products_v10-1_by_state_0501-1001_1x1");
/***** End of imports. If edited, may not auto-convert in the playground. *****/
// |
// | Landsat Time Series Harmonic Condition Assessment -- 
// | Visualize products
// | 
// | [valpasq@bu.edu], 2020
// |
// |
// | This script is used to add spatially smoothed and thresholded 
// | products to the map. All years added at once.

// -------------------- Image Collection ---------------------

var FINAL_PRODUCTS = v10_1_0510;

// ---------------------- Visualization ---------------------- 
var START_ASSESS = 2015;
var END_ASSESS = 2021;

var THRESHOLD = 2; 
var MIN_NOBS = 3;
var OUTPUT_SCALE = 1000;

var MIN = -4;
var MAX = 4;
var PALETTE = ['red', 'orange', 'white', 'teal', 'darkblue'];
var viz = {min: MIN, max: MAX, palette: PALETTE};

var water_mask = GSW.select('occurrence')
    .gte(50).unmask().not();

// ----------------------- Map Results ------------------------

var images = FINAL_PRODUCTS
    .filterMetadata('monitor_year', 'not_less_than', START_ASSESS)
    .filterMetadata('monitor_year', 'not_greater_than', END_ASSESS);
    
var years = images
    .aggregate_array('monitor_year')
    .distinct();
var num_years = years.size().getInfo();

// Loop over years to add each product to Map
for(var year = 0; year < num_years; year++){
  var year_value = years.get(year);
  
  var disp_img = images
      .filterMetadata('monitor_year', 'equals', year_value)
      .mosaic();

  var score_disp = disp_img
      .select(['score_mean', 'score_stddev', 
               'tcg_mean', 'tcg_stddev'])
      .divide(OUTPUT_SCALE);
  
  var thresh_mask = score_disp.select('score_mean').lte(THRESHOLD * -1)
      .or(score_disp.select('score_mean').gte(THRESHOLD));
  
  var nobs_mask = disp_img
      .select('total_nobs')
      .gte(MIN_NOBS);
  
  score_disp = score_disp
      .updateMask(thresh_mask)
      .updateMask(water_mask)
      .updateMask(nobs_mask);

  // c = (1 / (1 + s))^0.6;
  // c = (TanH(7*(c - 0.5)) + 1)*0.5;
  var confidence_scale = ee.Image(1)
      .divide(score_disp.select('score_stddev').add(1))
      .pow(0.6)
      .subtract(0.5).multiply(7)
      .tanh()
      .add(1).multiply(0.5);

  var score_mean_viz_alpha = score_disp.select('score_mean')
      .visualize(viz)
      .toUint8()
      .updateMask(thresh_mask.multiply(confidence_scale));
  
  var year_str = year_value.getInfo();
  
  // Map.addLayer(images.select('total_nobs'), {min:0, max: 10}, 'nobs ' + year_str, true);
  Map.addLayer(score_mean_viz_alpha, {}, 'score ' + year_str, true);
  Map.addLayer(images, {}, 'raw ' + year_str, false);
  
}

// ----------------------- Map Styling ------------------------
var stylers = require('users/valeriepasquarella/shared:map_stylers');
Map.setOptions('Dark', {Dark: stylers.dark_mode});
// Map.setOptions('SATELLITE');

// ------------------------------------------
// Create colorbar for legend.
function ColorBar(palette) {
  return ui.Thumbnail({
    image: ee.Image.pixelLonLat().select(0),
    params: {
      bbox: [0, 0, 1, 0.1],
      dimensions: '100x10',
      format: 'png',
      min: 0,
      max: 1,
      palette: palette,
    },
    style: {stretch: 'horizontal', margin: '2px 2px'},
  });
}

// Build legend
function makeLegend(palette) {
  var legendTitle = ui.Label({
    value: 'Detected Change in Greenness',
    style: {
      fontWeight: 'bold',
      fontSize: '13px',
      margin: '0 0 2px 0',
      padding: '0',
      backgroundColor: 'rgba(255, 255, 255, 0)'
    }
    });
    
  var labelPanel = ui.Panel({
      widgets: [
        ui.Label('Less Green', {margin: '0px 0px', backgroundColor: 'rgba(255, 255, 255, 0)', fontSize: '12px'}),
        ui.Label(' ', {margin: '0px 0px', textAlign: 'center', stretch: 'horizontal', backgroundColor: 'rgba(255, 255, 255, 0)', fontSize: '12px'}),
        ui.Label('More Green', {margin: '0px 0px',backgroundColor: 'rgba(255, 255, 255, 0)', fontSize: '12px'})
      ],
      layout: ui.Panel.Layout.flow('horizontal'),
      style: { backgroundColor: 'rgba(255, 255, 255, 0)'}});
  
  return ui.Panel({
    widgets: [legendTitle, ColorBar(palette), labelPanel],
    style: {position: 'bottom-right',
      backgroundColor: 'rgba(255, 255, 255, 0.75)'
    }
  });
}

Map.add(makeLegend(PALETTE));