GEE Feature Selection – How to Select Individual Feature from ImageCollection in Google Earth Engine

google-earth-engine

I am interested in using the .sampleRegions function to extract values from the following ImageCollection. In order to do this, I want to select the middle of the three images (index=1) contained within this image collection. Can anyone help me figure out how to select this image from the ImageCollection?

var MFR = ee.ImageCollection("LANDFIRE/Fire/MFRI/v1_2_0")
print(MFR)

output:

type: ImageCollection
id: LANDFIRE/Fire/MFRI/v1_2_0
version: 1633090983238815
bands: []
features: List (3 elements)
properties: Object (14 properties)

If I use .first(), I get the first image which has the desired form, but is the wrong image:

var MFR = ee.ImageCollection("LANDFIRE/Fire/MFRI/v1_2_0").first()
print(MFR)

output:

Image LANDFIRE/Fire/MFRI/v1_2_0/AK (1 band)
type: Image
id: LANDFIRE/Fire/MFRI/v1_2_0/AK
version: 1629985810765077
bands: List (1 element)
properties: Object (6 properties)

Is there an easy way to select the second image?

Best Answer

Since you know the image id from your script, you can call the image by image id. As in the code below:

var dataset = ee.Image('LANDFIRE/Fire/MFRI/v1_2_0/CONUS');

Related Solutions

Google Earth Engine – Using ee.Image.stratifiedSample() for Binary Classifier Training Samples

You're not doing anything wrong, it's just that S2 images have a lot of bands and taking the median() of them generates double valued pixels, so the tiles being passed back and forth between servers end up too large. When this occurs, you increase the tileScale, to tell the system to use smaller tiles.

var trainingSamples = s2_image.stratifiedSample({
  numPoints: 10, 
  classBand: 'binary_image', 
  region: ROI, 
  scale: 10,
  tileScale: 4
});

See https://developers.google.com/earth-engine/debugging#scaling-errors for more information on tileScale.

Google Earth Engine – Add Date to Band Names in ImageCollection

I am not sure if I understand your question, but I guess you struggle making one image of a collection, and rename the band to its according system:time_start property, formatted human readable.

Your question then is very similar to this question. For your example, most easiest would be:

var collection_asImage = LC08_collection.toBands();

This adds the sensor ID, the zones and the date in front of the band name. Possibly, this suites your needs.

The problem with your suggestion, only adding the date at the end, is that there could be multiple Landsat image with a similar date. Thus, the image band names will have similar names and the script will fail. A solution could be manually adding the zone:

// rename the bands using the system:time_start property (and zone if necesarry)
var LC08_collection_renamedBands = LC08_collection.map(function(image) {
    var dateFormatted = ee.String('_').cat(image.date().format('YYYY-MM-dd'));
    var zones = image.getString('system:index').slice(4,11);
    return image.rename(image.bandNames().map(function(bandName){
      return ee.String(bandName).cat(dateFormatted)
        .cat(zones);
    }));
  });

// Apply the function toBands() on the image collection to set all bands into one image
var collection_asImage = LC08_collection_renamedBands.toBands();

// then remove the by default prefixed ID 
var names = collection_asImage.bandNames();
// rename the bandnames 
var newNames = names.map(function(name){
  var ind = names.indexOf(name);
  return ee.String(names.get(ind)).slice(21);
});
var multiband = collection_asImage.rename(newNames);

Link to script option 1, and link option 2

Best Answer

Related Solutions

Google Earth Engine – Using ee.Image.stratifiedSample() for Binary Classifier Training Samples

Google Earth Engine – Add Date to Band Names in ImageCollection

Related Question