Landsat Algorithms

Landsat collection structure

The USGS has moved to using a collection-based strategy for producing Landsat scenes. On May 1st, 2017, they stopped producing old-style (pre-Collection) scenes and now are only producing Collection 1 versions.

The USGS now produces data in 3 categories for each satellite:


In order to allow access to both the validated T1 data and the newest real-time data together, we've sorted the scenes into 3 collections (per each satellite) as follows:

ID Description


Each of these collections contains the raw data (i.e., scaled, at-sensor radiance). In addition, for each collection that contains T1 data, we are also providing a TOA collection containing the top-of-atmosphere reflectance. (e.g.: LANDSAT/LC08/C01/T1_RT_TOA).

Finally, because pre-Collection 1 scenes are no longer being produced, we will not be able to update the "old-style" Landsat collections (e.g.: LANDSAT/LC8_L1T). We plan to keep these collections for a while even after we've obtained all of the C1 data, but they will eventually be phased out.

Landsat processing methods


At-sensor radiance and TOA reflectance


// Load a raw Landsat scene and display it.
Map.centerObject(raw, 10);

// Convert the raw data to radiance.
var radiance = ee.Algorithms.Landsat.calibratedRadiance(raw);

var toa = ee.Algorithms.Landsat.TOA(raw);


Surface reflectance

Conversion to surface reflectance generally requires some sort of atmospheric compensation. USGS uses the LEDAPS software (Schmidt et al. 2013) to convert raw Landsat data to surface reflectance. LEDAPS requires a variety of atmospheric inputs to constrain an atmospheric model. These include outputs of a 6S model run, a DEM, total column ozone, National Centers for Environmental Prediction (NCEP) modeled surface pressure, temperature and water vapor (Kalnay et al. 1996).

You can access pre-computed surface reflectance images directly from the SR collections. For example, to load a Landsat 7 surface reflectance image, use:

var srImage = ee.Image('LANDSAT/LE07/C01/T1_SR/LE07_044034_19990707');

The surface reflectance datasets for Collection 1 Landsat 4 through 7 are:

var surfaceReflectanceL4 = ee.ImageCollection('LANDSAT/LT04/C01/T1_SR');
var surfaceReflectanceL5 = ee.ImageCollection('LANDSAT/LT05/C01/T1_SR');
var surfaceReflectanceL7 = ee.ImageCollection('LANDSAT/LE07/C01/T1_SR');

Simple cloud score


// Load a cloudy Landsat scene and display it.

var scored = ee.Algorithms.Landsat.simpleCloudScore(cloudy_scene);


var masked = cloudy_scene.updateMask(mask);

  .set('SENSOR_ID', 'OLI_TIRS');

// Cloud score the mosaic and display the result.
var scored_mosaic = ee.Algorithms.Landsat.simpleCloudScore(mosaic);
    'TOA mosaic', false);



  .set('SENSOR_ID', 'OLI_TIRS');

// Cloud score the mosaic and display the result.
var scored_mosaic = ee.Algorithms.Landsat.simpleCloudScore(mosaic);
    'TOA mosaic', false);


Simple composite



// Create a cloud-free composite with default parameters.
var composite = ee.Algorithms.Landsat.simpleComposite(collection);

// Create a cloud-free composite with custom parameters for
// cloud score threshold and percentile.
var customComposite = ee.Algorithms.Landsat.simpleComposite({
  collection: collection,
  percentile: 75,
  cloudScoreRange: 5

// Display the composites.
Map.setCenter(-122.3578, 37.7726, 10);
    'Custom TOA composite');


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