Global Building Atlas Polygons¶

// Load sample building polygon data - replace 'TILE_ID' with specific tile identifier
var gba_polygons = ee.FeatureCollection("projects/sat-io/open-datasets/GLOBAL_BUILDING_ATLAS/e030_n25_e035_n20");

// Filter buildings with height information
var buildings_with_height = gba_polygons.filter(
  ee.Filter.and(
    ee.Filter.neq('height', null),
    ee.Filter.gt('height', 0)
  )
);

// Method 1: Color by height ranges using separate layers (more precise control)
var heightRanges = [
  {min: 0, max: 5, color: '440154', label: '< 5m (Low)'},
  {min: 5, max: 10, color: '31688e', label: '5-10m (Medium-low)'},
  {min: 10, max: 20, color: '35b779', label: '10-20m (Medium-high)'},
  {min: 20, max: 999, color: 'fde725', label: '≥ 20m (Tall)'}
];

// Add layers for each height range
heightRanges.forEach(function(range) {
  var rangeFilter = ee.Filter.and(
    ee.Filter.gte('height', range.min),
    ee.Filter.lt('height', range.max)
  );

  var rangeBuildings = buildings_with_height.filter(rangeFilter);

  Map.addLayer(
    rangeBuildings,
    {color: range.color, width: 1, fillColor: range.color},
    'Height ' + range.label,
    true,
    0.8
  );
});

// Calculate building statistics
print('Total building polygons in tile:', gba_polygons.size());
print('Buildings with height data:', buildings_with_height.size());

// Filter large buildings by area and use simple style
var large_buildings = gba_polygons.filter(ee.Filter.gt('area', 500));
Map.addLayer(large_buildings.style({color: 'red'}), {}, 'Large Buildings (>500m²)');

// Get height statistics
var height_stats = buildings_with_height.aggregate_stats('height');
print('Height statistics:', height_stats);

// Create height legend panel
function createLegendRow(color, text) {
  return ui.Panel({
    widgets: [
      ui.Label({
        value: '●',
        style: {
          color: color,
          fontSize: '16px',
          margin: '0px 8px 0px 0px',
          padding: '0px',
          width: '16px',
          textAlign: 'left'
        }
      }),
      ui.Label({
        value: text,
        style: {
          fontSize: '12px',
          margin: '0px',
          padding: '0px'
        }
      })
    ],
    layout: ui.Panel.Layout.flow('horizontal'),
    style: {
      margin: '2px 0px',
      padding: '0px'
    }
  });
}

var legendPanel = ui.Panel({
  widgets: [
    ui.Label({
      value: 'Building Heights Legend',
      style: {fontWeight: 'bold', fontSize: '14px', margin: '0 0 8px 0'}
    }),
    createLegendRow('#440154', '< 5m (Low buildings)'),
    createLegendRow('#31688e', '5-10m (Medium-low)'),
    createLegendRow('#35b779', '10-20m (Medium-high)'),
    createLegendRow('#fde725', '≥ 20m (Tall buildings)')
  ],
  style: {
    position: 'bottom-right',
    padding: '12px',
    backgroundColor: 'rgba(255, 255, 255, 0.9)',
    border: '1px solid #ccc',
    width: '200px'
  }
});

Map.add(legendPanel);

// Center map on the tile extent
Map.setCenter(32.90,24.06, 15);