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Here is the code. There are 81 sentinel images but I am only seeing the first one (or the last one maybe), how can I visualize other images. Let's say I want to see the 2nd one ?

// Importing S-1 Images
var S1 = ee.ImageCollection("COPERNICUS/S1_GRD");

// Importing Geometry (area of Interest)
geometry = 
ee.Geometry.Polygon(
    [[[74.38065032641738, 12.778968253582836],
      [74.38065032641738, 7.612293582692355],
      [77.74246673266738, 7.612293582692355],
      [77.74246673266738, 12.778968253582836]]], null, false);

// Define Time Interval 
var start_date = ee.Date('2018-07-21');
var end_date = start_date.advance(3, 'month');
var date_filter = ee.Filter.date(start_date, end_date);

//Display of Image 
var collection2 = S1
    .filter(date_filter)
    .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV'))
    .filter(ee.Filter.eq('instrumentMode', 'IW'))
    .filterBounds(geometry);
var vis_params2 = {bands:'VV', min:-25, max:5};
var label2 = 'SAR Backscatter';


// Visualizing the map
Map.addLayer(collection2, vis_params2, 'secondimg')
Map.centerObject(geometry);

1 Answer 1

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When you add an ee.ImageCollection() to the Map, you see the Mosaic of the imagecollection. Note that there is no single date of acquiring a mosaic image- it is a synthetic image composed of the latest available image for each pixel in a queried geometry.

If you want to specifically obtain the nth image in an imagecollection, convert it to a list and plot only the nth element of that list like so:

var n = 50;
var imageList = collection2.toList(n); //convert image collection to list
var image = ee.Image(imageList.get(n-1)); //obtain nth image from 0 indexed list
// Visualizing the map
Map.addLayer(image, vis_params2, 'nthImg') //add nth image to Map

Again, note that since Sentinel-1 doesn't have a fixed acquisition mode over India, the nth image may or may not cover the entire geometry you queried.

Link to corrected code.

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  • Thankyou. I got the concept now :) Nov 17, 2020 at 2:02
  • Thanks. a follow up question How can I change tohe label of the image (Lets say I am looking for 2nd image and I want its label as its date of acquisition. Jan 10, 2021 at 0:55
  • Use var image = image.set({"system:id":image.get("system:time_start")})
    – kkrao
    Jan 10, 2021 at 5:57

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