Why can not Landsat 5 image use Fmask algorithm to identify cloud?

Question

I want to get 1990 NDVI from Landsat5,and remove the cloud cover, so I used the code:

var addNDVI = function(image) {
  var ndvi = image.normalizedDifference(['B4', 'B3']).rename('NDVI');
  return image.addBands(ndvi);
};

var addFmask = function(image) {
  var datamask = image.select('fmask');
  var cloudMask = datamask.neq(1).and(datamask.neq(2)).and(datamask.neq(3)).and(datamask.neq(4));
  return image.updateMask(cloudMask);
};

var collection2 = ee.ImageCollection('LANDSAT/LT5_L1T_TOA_FMASK')
    .filterBounds(alb)
    .filterDate('1991-01-01', '1991-12-31')
    .select(['B3', 'B4', 'fmask'])
    .map(addFmask)
    .map(addNDVI).select('NDVI');

When I run this code, I got the error as below:

Error generating chart: ImageCollection.load: Use LANDSAT/LT05/C01/T1_SR instead of LANDSAT/LT5_L1T_TOA_FMASK

So, I'm wonder if there are any question to use Fmask algorithm in the Landsat5 or I need to make some correction?

Answer 1

The LANDSAT/LT5_L1T_TOA_FMASK dataset has been deprecated in favor of Collection 1 datasets for Landsat 5, which use the format LANDSAT/LT05/C01/*. This change follows the USGS' Landsat Collections reorganization that occurred in 2016.

Collection 1 images include QA bands that provide cloud and shadow information, similar to the older *_TOA_FMASK images. For example, the USGS Landsat 5 Surface Reflectance Tier 1 (LANDSAT/LT05/C01/T1_SR) has a sr_cloud_qa band. You will need to update your code to use the new band names and modify the masking logic.