How to plot scattered point of NDVI and draw the trend in google earth engine - google-earth-engine

Question

I am using 'USGS Landsat 8 Level 2, Collection 2, Tier 1' Landsat to calculate mean NDVI and plot the trend from the scattered plot.
I have used the following code:
For importing file:
var imageCollection 'USGS Landsat 8 Level 2, Collection 2, Tier 1'
var Table 'the shapefile'
// Define a function that will add an NDVI band to a Landsat 8 image.
var addNDVI = function(image) {
var ndvi = image.normalizedDifference(['SR_B5', 'SR_B4']).rename('NDVI');
return image.addBands(ndvi);
};
function add_NDVI_collection(image_IC){
var NDVI_IC = table.map(addNDVI);
return NDVI_IC;
}
// Filter and map the function over the collection.
var withNDVI = imageCollection.filterDate('2015-01', '2015-12')
.map(addNDVI); // <-- map() the function over the collection.
// Filter and map the function over the collection.
// Make a chart.
var chart = ui.Chart.image.series({
imageCollection: withNDVI.select('NDVI'),
region: table, //again, here the ROI is a single point
reducer: ee.Reducer.mean()})
// Define custom options for the chart. See:
// https://developers.google.com/chart/interactive/docs/reference
var options = {
title: 'NDVI over time',
hAxis: { title: 'time' ,format: 'YYYY-MMM',gridlines:{count:12}},
vAxis: { title: 'NDVI' },
series: {
0: { color: 'blue' }
}
};
// Set the options of the chart and print it.
chart = chart.setOptions(options);
print(chart); // Put it in the console
I got the following plot:
How can I plot the scattered point instead of the connecting line for the NDVI and draw the trend by removing outlier?

Answer 1

You can use this tutorial to have full control over your chart.
For smoothing your curve:
.setOptions({
curveType: 'function'
})
For showing the points
{
pointSize: 10
}