I'm new in Google Earth Engine. I want to extract the value of NDVI for a series of MODIS images using a shapefile and after export the database.
This is my script:
var vect = ee.FeatureCollection("route of shapefile");
Map.addLayer(vect);
Map.centerObject(vect,4);
//Modis collection
var poly = ee.Geometry.Polygon([
[[15.71 , 51.403], [20.687, 51.259], [19.918, 54.614],
[16.007, 54.595]]]); //Interest area
var start = ee.Date('2015-03-01');
var finish = ee.Date('2018-06-01');
var modis_collection = ee.ImageCollection('MODIS/006/MOD13A1')
.filterBounds(poly_vect)
.filterDate(start,finish)
.select ('NDVI');// select NDVI image
And now? I suppose I should use ee.reduce to extract the values?
Best Answer
The MODIS images are global, so that filterBounds doesn't do any good. But you extract values using reduceRegion if you want 1 value for the whole shapefile or reduceRegions() if you want it for each geometry. If you want to do that for every image in your collection, you map a function over the collection:
The map() will produce a collection of collections, which you then flatten() into a single table. If you want to get that out to use in another tool, you Export it as a table.