Filter Landsat Images - cloud cover

Question

I'm trying to filter Landsat images based on the percent of cloud cover for my ROI. I have tried to adapt code in link one and link two but cannot get what I want. My ROI has been imported as a feaureCollection and covers 8 Landsat tiles.

This is my code

//select images from image collection
var l8 = ee.ImageCollection('LANDSAT/LC08/C01/T1')
//LT05, LE07, LC08
.filterDate('1980-01-01', '2018-12-31')
.filter(ee.Filter.or(
ee.Filter.and(ee.Filter.eq('WRS_PATH', 208),         
              ee.Filter.eq('WRS_ROW', 22)),
ee.Filter.and(ee.Filter.eq('WRS_PATH', 208),         
              ee.Filter.eq('WRS_ROW', 23)),
ee.Filter.and(ee.Filter.eq('WRS_PATH', 208),         
              ee.Filter.eq('WRS_ROW', 24)),              
ee.Filter.and(ee.Filter.eq('WRS_PATH', 207),         
              ee.Filter.eq('WRS_ROW', 22)),              
ee.Filter.and(ee.Filter.eq('WRS_PATH', 207),         
              ee.Filter.eq('WRS_ROW', 23)),              
ee.Filter.and(ee.Filter.eq('WRS_PATH', 207),         
              ee.Filter.eq('WRS_ROW', 24)),
ee.Filter.and(ee.Filter.eq('WRS_PATH', 206),         
              ee.Filter.eq('WRS_ROW', 23)),
ee.Filter.and(ee.Filter.eq('WRS_PATH', 206),         
              ee.Filter.eq('WRS_ROW', 24))));

var c = l8.map(function(img) { return img.clip(my_geom); });

var withCloudiness = c.map(function(image) {
var cloud = ee.Algorithms.Landsat.simpleCloudScore(image).select('cloud');
var cloudiness = cloud.reduceRegion({
reducer: 'mean', 
geometry: my_geom, 
scale: 30,
});

return image.set(cloudiness);
});
var filteredCollection = withCloudiness.filter(ee.Filter.lt('cloud', 20));
print(filteredCollection);

So I have two problems:

1: When using Landsat 8, the code runs, but it does not filter based on a threshold, 20% in this case. When i write the output to a file it gives two columns, cloud_cover and cloud_cover_land, both have observations of cloud greater than 20%.

2: When I try using Landsat 5 or 7 my file is empty...but I know there are scenes that are below 20% cloud cover for Landsat 5.

What I am I doing wrong?

Answer 1

The problem is that simpleCloudScore wants a TOA image and you're passing it raw images. The fact that L8 does anything is simply coincidence.

var c = ee.ImageCollection('LANDSAT/LT05/C01/T1_TOA')
  .filterDate('1980-01-01', '2018-12-31')
  .filter(ee.Filter.rangeContains('WRS_PATH', 206, 208))
  .filter(ee.Filter.rangeContains('WRS_ROW', 22, 24))

var withCloudiness = c.map(function(image) {
  var cloud = ee.Algorithms.Landsat.simpleCloudScore(image).select('cloud');
  var cloudiness = cloud.reduceRegion({
    reducer: 'mean', 
    geometry: my_geom, 
    scale: 30,
  });

  return image.set(cloudiness);
});

var filteredCollection = withCloudiness.filter(ee.Filter.lt('cloud', 20));

print(withCloudiness.size())
print(filteredCollection.size());

Answer 2

About your second question, try this way to filter clouds from all collections

//mascara de nuvem e sombra

function maskL8sr(image) {
  // Bits 3 and 5 are cloud shadow and cloud, respectively.
  var cloudShadowBitMask = (1 << 3);
  var cloudsBitMask = (1 << 5);
  // Get the pixel QA band.
  var qa = image.select('pixel_qa');
  // Both flags should be set to zero, indicating clear conditions.
  var mask = qa.bitwiseAnd(cloudShadowBitMask).eq(0)
                 .and(qa.bitwiseAnd(cloudsBitMask).eq(0));
  return image.updateMask(mask);
}

///PADRONIZAR NOME DAS BANDAS____________________________________________________________________________________

var bname = ['blue', 'green', 'red', 'nir', 'swir1', 'swir2', 'temp','pixel_qa']
var bl4 = ['B1',   'B2',    'B3',  'B4',  'B5',    'B7',    'B6', 'pixel_qa'] //Landsat 7
var bl5 = ['B1',   'B2',    'B3',  'B4',  'B5',    'B7',    'B6', 'pixel_qa'] //Landsat 7
var bl7 = ['B1',   'B2',    'B3',  'B4',  'B5',    'B7',    'B6', 'pixel_qa'] //Landsat 7
var bl8 = ['B2',   'B3',    'B4',  'B5',  'B6',    'B7',    'B10', 'pixel_qa'] //Landsat 8

var rename_bands = function(img,input) {
return img.select(input, bname)
}

//IMPORTAR COLEÇÕES

var L4 = ee.ImageCollection("LANDSAT/LT04/C01/T1_SR")
           //.filterDate('1982-01-01', '1993-12-01')
           .filterMetadata('CLOUD_COVER', 'less_than',10)
           .filterBounds(table)
           //.map(cloudMaskL457)
           .map(function(image){return image.clip(table)})

print('L4', L4)           
           
var L5 = ee.ImageCollection("LANDSAT/LT05/C01/T1_SR")
           //.filterDate('1984-01-01', '2012-05-05')
           .filterMetadata('CLOUD_COVER', 'less_than',10)
           .filterBounds(table)
           //.map(cloudMaskL457)
           .map(function(image){return image.clip(table)})
           
print ('l5', L5)

var L7 =  ee.ImageCollection('LANDSAT/LE07/C01/T1_SR')
            .filterDate('1999-01-01', '2004-12-31')
           .filterMetadata('CLOUD_COVER', 'less_than',10)
           .filterBounds(table)
           //.map(cloudMaskL457)
           .map(function(image){return image.clip(table)})
                     
print('L7', L7)    

var L8 =  ee.ImageCollection("LANDSAT/LC08/C01/T1_SR")
           //.filterDate('2013-04-01', '2020-12-16')
           .filterMetadata('CLOUD_COVER', 'less_than',10)
           .filterBounds(table)
           .map(function(image){return image.clip(table)});                     

print('l8', L8)
 
//RENOMEAR BANDAS E JUNTAR

var L4n  = rename_bands(L4, bl4)    
var L5n  = rename_bands(L5, bl5)
var L7n  = rename_bands(L7, bl7)
var L8n  = rename_bands(L8, bl8)

var lsat = L4n.merge(L5n).merge(L7n).merge(L8n)
              //.filterMetadata('CLOUD_COVER', 'less_than',10)
             // .filterMetadata('IMAGE_QUALITY', 'equals', 9)
                .map(maskL8sr);

print('COLEÇÃO', lsat)