The Normalized Difference Vegetation Index (NDVI) is a simple graphical indicator that can be used to analyze remote sensing measurements, typically, but not necessarily, from a space platform, and assess whether the target being observed contains live green vegetation or not.
The NDVI is calculated from these individual measurements as follows:
NDVI= (NIR-Red) \ (NIR+Red)
The following code is available in “Panels and Layout” page of Google Earth Engine Developer page. I found it interesting and worth-sharing so I copied the code as it is here. If you want to learn more about it, please go here:
// Source: https://developers.google.com/earth-engine/ui_panels
// Load and display NDVI data.
var ndvi = ee.ImageCollection('LANDSAT/LC8_L1T_8DAY_NDVI')
.filterDate('2014-01-01', '2015-01-01');
Map.addLayer(ndvi.median(), {min: 0, max: 1, palette: ['99c199', '006400']}, 'NDVI');
// Configure the map.
Map.setCenter(-94.84497, 39.01918, 8);
Map.style().set('cursor', 'crosshair');
// Create an empty panel in which to arrange widgets.
// The layout is vertical flow by default.
var panel = ui.Panel({style: {width: '400px'}})
.add(ui.Label('Click on the map'));
// Set a callback function for when the user clicks the map.
Map.onClick(function(coords) {
// Create or update the location label (the second widget in the panel)
var location = 'lon: ' + coords.lon.toFixed(2) + ' ' +
'lat: ' + coords.lat.toFixed(2);
panel.widgets().set(1, ui.Label(location));
// Add a red dot to the map where the user clicked.
var point = ee.Geometry.Point(coords.lon, coords.lat);
Map.layers().set(1, ui.Map.Layer(point, {color: 'FF0000'}));
// Create a chart of NDVI over time.
var chart = ui.Chart.image.series(ndvi, point, ee.Reducer.mean(), 200)
.setOptions({
title: 'NDVI Over Time',
vAxis: {title: 'NDVI'},
lineWidth: 1,
pointSize: 3,
});
// Add (or replace) the third widget in the panel by
// manipulating the widgets list.
panel.widgets().set(2, chart);
});
// Add the panel to the ui.root.
ui.root.add(panel);