/*******************************************
* GEE Nighttime Lights Visualization Code
*******************************************/
/*******************************************
* Section: Data Loading and Preprocessing
*******************************************/
// Function to load calibrated nighttime light (NTL) images for a given year
function loadNTL(year) {
return ee.Image('projects/ee-carlosmendez777/assets/NTL_RC_calibrated/NTL' + year)
.selfMask(); // Mask out invalid pixels
}
// Load Indian states dataset from geoBoundaries and filter for India
var indianStates = ee.FeatureCollection("projects/earthengine-legacy/assets/projects/sat-io/open-datasets/geoboundaries/CGAZ_ADM1")
.filter(ee.Filter.eq('shapeGroup', 'IND'));
// Load nighttime lights images for 1996 and 2010
var ntl1996 = loadNTL(1996);
var ntl2010 = loadNTL(2010);
/*******************************************
* Section: Visualization Parameters
*******************************************/
// Visualization parameters for nighttime lights
var vis = {
min: 2.0,
max: 16.0,
palette: ['#253494', '#2c7fb8', '#41b6c4', '#a1dab4', '#ffffcc'],
opacity: 0.75
};
// Dark Basemap style configuration for UI maps
var styledMapType = {
Dark: [
{ "featureType": "all", "elementType": "labels.text.fill",
"stylers": [{ "saturation": 36 }, { "color": "#000000" }, { "lightness": 40 }] },
{ "featureType": "all", "elementType": "labels.text.stroke",
"stylers": [{ "visibility": "on" }, { "color": "#000000" }, { "lightness": 16 }] },
{ "featureType": "all", "elementType": "labels.icon",
"stylers": [{ "visibility": "off" }] },
{ "featureType": "administrative", "elementType": "geometry.fill",
"stylers": [{ "color": "#000000" }, { "lightness": 20 }] },
{ "featureType": "administrative", "elementType": "geometry.stroke",
"stylers": [{ "color": "#000000" }, { "lightness": 17 }, { "weight": 1.2 }] },
{ "featureType": "landscape", "elementType": "geometry",
"stylers": [{ "color": "#000000" }, { "lightness": 20 }] },
{ "featureType": "poi", "elementType": "geometry",
"stylers": [{ "color": "#000000" }, { "lightness": 21 }] },
{ "featureType": "road.highway", "elementType": "geometry.fill",
"stylers": [{ "color": "#000000" }, { "lightness": 17 }] },
{ "featureType": "road.highway", "elementType": "geometry.stroke",
"stylers": [{ "color": "#000000" }, { "lightness": 29 }, { "weight": 0.2 }] },
{ "featureType": "road.arterial", "elementType": "geometry",
"stylers": [{ "color": "#000000" }, { "lightness": 18 }] },
{ "featureType": "road.local", "elementType": "geometry",
"stylers": [{ "color": "#000000" }, { "lightness": 16 }] },
{ "featureType": "transit", "elementType": "geometry",
"stylers": [{ "color": "#000000" }, { "lightness": 19 }] },
{ "featureType": "water", "elementType": "geometry",
"stylers": [{ "color": "#000000" }, { "lightness": 17 }] }
]
};
/*******************************************
* Section: Map Initialization and UI Setup
*******************************************/
var center = { lon: 78.96288, lat: 20.593684, zoom: 6 };
var leftMap = ui.Map(center);
var rightMap = ui.Map(center);
leftMap.setOptions('Dark', {'Dark': styledMapType.Dark});
rightMap.setOptions('Dark', {'Dark': styledMapType.Dark});
var linker = ui.Map.Linker([leftMap, rightMap]);
var splitPanel = ui.SplitPanel({
firstPanel: leftMap, secondPanel: rightMap,
orientation: 'horizontal', wipe: true
});
ui.root.clear();
ui.root.add(splitPanel);
/*******************************************
* Section: Layer Addition
*******************************************/
leftMap.addLayer(ntl1996.clip(indianStates), vis, 'NTL 1996');
rightMap.addLayer(ntl2010.clip(indianStates), vis, 'NTL 2010');
var stateStyle = { color: 'white', fillColor: '00000000', width: 1 };
leftMap.addLayer(indianStates.style(stateStyle), {}, 'State Boundaries');
rightMap.addLayer(indianStates.style(stateStyle), {}, 'State Boundaries');
leftMap.add(ui.Label({ value: 'Luminosity in 1996',
style: { fontSize: '25px', backgroundColor: '#f7f7f7', position: 'top-left' } }));
rightMap.add(ui.Label({ value: 'Luminosity in 2010',
style: { fontSize: '25px', backgroundColor: '#f7f7f7', position: 'top-right' } }));
/*******************************************
* Section: Legend Creation
*******************************************/
function createLegendPanel() {
var legendPanel = ui.Panel({
style: { position: 'bottom-right', padding: '8px',
backgroundColor: '#f7f7f7', border: '1px solid #cccccc' }
});
legendPanel.add(ui.Label({ value: 'Nighttime Light Intensity',
style: { fontWeight: 'bold', fontSize: '16px', margin: '0 0 6px 0', padding: '0' } }));
var colorBar = ui.Thumbnail({
image: ee.Image.pixelLonLat().select(0),
params: { bbox: [0, 0, 1, 0.1], dimensions: '200x10', format: 'png',
min: 0, max: 1, palette: ['#253494', '#2c7fb8', '#41b6c4', '#a1dab4', '#ffffcc'] },
style: { stretch: 'horizontal', margin: '0 0 6px 0', maxHeight: '24px' }
});
legendPanel.add(colorBar);
var labelPanel = ui.Panel({
widgets: [
ui.Label(vis.min.toFixed(1), { margin: '0', fontSize: '12px' }),
ui.Label(((vis.max - vis.min) / 2 + vis.min).toFixed(1),
{ margin: '0', textAlign: 'center', stretch: 'horizontal', fontSize: '12px' }),
ui.Label(vis.max.toFixed(1), { margin: '0', fontSize: '12px' })
],
layout: ui.Panel.Layout.flow('horizontal'),
style: { stretch: 'horizontal' }
});
legendPanel.add(labelPanel);
legendPanel.add(ui.Label('Digital number (DN)',
{ margin: '3px 0 0 0', fontSize: '12px', textAlign: 'center' }));
return legendPanel;
}
leftMap.add(createLegendPanel());
rightMap.add(createLegendPanel());
