Apply a mask (shapefile) over a satellite image in Google Earth Engine

Question

I have a Sentinel 2 satellite image and am rating it. I already classified all the native vegetation separated into a shapefile. Now I need to classify the anthropic uses, I would like the GEE to classify this image but ignore the vegetation areas indicated in the shapefile, how could I do this. I tried this solution Using FeatureCollection to mask an image in Google Earth Engine?, bbut I couldn't replicate,because GEE says "ifc is not a function". How to make it?

Ny code:

var img1 = ee.ImageCollection("COPERNICUS/S2_SR")
.filterMetadata('MGRS_TILE', 'equals', '21KYT')
.filterMetadata('CLOUDY_PIXEL_PERCENTAGE','less_than', 1) 
//.filterMetadata('CLOUD_COVER', 'less_than', 0.01)
.filterDate('2020-01-01','2020-12-26')
.select(['B4', 'B3', 'B2'])
.median();
var img2 = img1.clip(table)
//add a região de interesse
var regiao = img1;
//add info iniciais para o treinamento
var treinamento = img1.sample({
 region: table,
 scale: 10,
 numPixels: 450,
});
//var agrupamento = ee.Clusterer.wekaLVQ(9, 0.1).train(treinamento);//6 6,1
//var agrupamento2 = ee.Clusterer.wekaLVQ(9, 0.7).train(treinamento);//6 6,1
var agrupamento3 = ee.Clusterer.wekaLVQ(9, 1).train(treinamento);//6 6,1
//var resultado = img1.cluster(agrupamento);
//var resultado2 = img1.cluster(agrupamento2);
var resultado3 = img1.cluster(agrupamento3);
//Map.addLayer(resultado, {min:0, max: 6, palette: ['#8668d7', '#03a2b8', '#607f72', 'red', '#5d8f5b', '#e624b6', ]}, 'Resultado_Unsup');
//Map.addLayer(resultado2, {min:0, max: 6, palette: ['#8668d7', '#03a2b8', '#607f72', 'red', '#5d8f5b', '#e624b6', ]}, 'Resultado_Unsup2');
Map.addLayer(resultado3, {min:0, max: 6, palette: ['#8668d7', '#03a2b8', '#607f72', 'red', '#5d8f5b', '#e624b6', ]}, 'Resultado_Unsup3');
//Map.addLayer(image, {bands: ['B4', 'B3', 'B2'], min:178, max:1110},  'S2');
// Export the image, specifying scale and region.
Export.image.toDrive({
 image: resultado3.float(),
  description: 'unsup_Sentinel_9',
  scale: 10,
  region: table,
  folder: 'GEE_Ceroula_3',
  //crs: 'EPSG:32721'
  });
var styling = {color: 'yellow', fillColor: '00000000'};
Map.addLayer(table.style(styling));
Map.centerObject(table, 10);

Philipe Riskalla Leal · Accepted Answer · 2020-12-16T20:01:40.713

The solution for your problem lies in a three-step processing:

Rasterizing your table (a FeatureCollection) according to a given numerical property (i.e. landuse_type)
Create a mask which will contain all pixels which do belong to a given class (i.e.: the vegetation class).

Small note: It is important to remember that the vegetation class in each pixel will be a value, and not a string.

Finally, make an UpdateMask using your created maks over your ImageCollection (i.e.: Sentinel images)

After these three steps, the rest of your training code will work just fine.

Here is an example which you can check it out:

https://code.earthengine.google.com/9fc631eba38a3f6d7e16deffb0b80fc2

Below I paste the respective link's code:

table = table.map(function(feat){
var CD_GEOCME = ee.Number.parse(ee.String(feat.get('CD_GEOCME')).slice(0,4));
return feat.set('CD_GEOCME',CD_GEOCME )});
print(table);
var Image_from_table = table.reduceToImage(['CD_GEOCME'], ee.Reducer.first() ).rename('CD_GEOCME');
print(Image_from_table, 'Image_from_table');
Map.addLayer(Image_from_table, imageVisParam, 'Image_from_table');
var class_number = 1505; 
var mask = Image_from_table.neq(class_number) // preserves all classes that are not 1505
var img1 = ee.ImageCollection("COPERNICUS/S2")
           .filterBounds(table)
           .mosaic()
           .updateMask(mask);
//add info iniciais para o treinamento
var treinamento = img1.sample({
 region: table,
 tileScale :12,
numPixels:15, 
 scale:50000
});
//var agrupamento = ee.Clusterer.wekaLVQ(9, 0.1).train(treinamento);//6 6,1
//var agrupamento2 = ee.Clusterer.wekaLVQ(9, 0.7).train(treinamento);//6 6,1
var agrupamento3 = ee.Clusterer.wekaLVQ(9, 1).train(treinamento);//6 6,1
//var resultado = img1.cluster(agrupamento);
//var resultado2 = img1.cluster(agrupamento2);
var resultado3 = img1.cluster(agrupamento3);
print(resultado3, 'resultado3')
//Map.addLayer(resultado, {min:0, max: 6, palette: ['#8668d7', '#03a2b8', '#607f72', 'red', '#5d8f5b', '#e624b6', ]}, 'Resultado_Unsup');
//Map.addLayer(resultado2, {min:0, max: 6, palette: ['#8668d7', '#03a2b8', '#607f72', 'red', '#5d8f5b', '#e624b6', ]}, 'Resultado_Unsup2');
Map.addLayer(resultado3, {min:0, max: 6, palette: ['#8668d7', '#03a2b8', '#607f72', 'red', '#5d8f5b', '#e624b6', ]}, 'Resultado_Unsup3');
//Map.addLayer(image, {bands: ['B4', 'B3', 'B2'], min:178, max:1110},  'S2');
// Export the image, specifying scale and region.
Export.image.toDrive({
 image: resultado3.float(),
  description: 'unsup_Sentinel_9',
  scale: 10,
  region: table,
  folder: 'GEE_Ceroula_3',
  //crs: 'EPSG:32721'
  });
var styling = {color: 'yellow', fillColor: '00000000'};
Map.addLayer(table.style(styling), {}, 'Polygon borders', false);
Map.centerObject(table, 5);

hello Philip. Your answer helped me when you mentioned the need to convert the shapefile to a raster. But I was unable to replicate your code. But his help was a light, as he was working only with shapefile. Thank you very much!!!! — wesleysc352, Dec 16 '20 at 15:15

Apply a mask (shapefile) over a satellite image in Google Earth Engine

1 Answers1