Hello I dont know anything to this but I just have one mistake in my code I dont know why
// Load country features from Large Scale International Boundary (LSIB) dataset.
var countries = ee.FeatureCollection('USDOS/LSIB_SIMPLE/2017');
var roi = countries.filter(ee.Filter.eq('country_co', 'CB'));
Map.addLayer(roi,{},'Cambodia')
//Let's centre the map view over our ROI
Map.centerObject(roi, 6);
// Filter the collection for the VV product from the descending track
var collectionVV = ee.ImageCollection('COPERNICUS/S1_GRD')
.filter(ee.Filter.eq('instrumentMode', 'IW'))
.filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV'))
.filter(ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))
.filterBounds(roi)
.select(['VV'])
.median();
// Filter the collection for the VH product from the descending track
var collectionVH = ee.ImageCollection('COPERNICUS/S1_GRD')
.filter(ee.Filter.eq('instrumentMode', 'IW'))
.filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
.filter(ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))
.filterBounds(roi)
.select(['VH'])
.median();
// Adding the VV layer to the map at a specific date
var image = ee.Image(collectionVV.filterDate('2020-10-14', '2020-10-20').median());
Map.addLayer(image.clip(roi), {min: -25, max: 5}, 'Image_VV');
it is for the last line I get :
Line 29: collectionVV.filterDate is not a function
Thanks
Since you end your two expressions for collectionVV and collectionVH with the .median() operation, you already reduce both ImageCollections to an image (by taking the median of that collection). Simply removing the .median() statements will fix your error. Thus:
// Filter the collection for the VH product from the descending track
var collectionVH = ee.ImageCollection('COPERNICUS/S1_GRD')
.filter(ee.Filter.eq('instrumentMode', 'IW'))
.filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))
.filter(ee.Filter.eq('orbitProperties_pass', 'DESCENDING'))
.filterBounds(roi)
.select(['VH'])
//.median();
// Adding the VV layer to the map at a specific date
var image = ee.Image(collectionVH.filterDate('2020-10-14', '2020-10-20').median());
Map.addLayer(image.clip(roi), {min: -25, max: 5}, 'Image_VV');