Simple assignment to use SAR.
1. Importing the Data.
Step 1: Go to the Google Earth Engine.
Step 2: Import the Sentinel-1 image collection and call it SAR.
Step 3: Add a marker at Bangkok and call the marker roi.
Step 4: add the code below to the script.
// filter on location var mySAR = SAR.filterBounds(roi) // print the image collection print(mySAR)
Question 1: How many images are there in the image collection.
Question 2: How many bands are there in each image, what do they represent?
2. Displaying Data
Step 5: Use the previous script and add the code below.
// imageCollection to list var mylist= mySAR.toList(500) // get the angle of first image var myAngle = ee.Image(mylist.get(1)).select("angle") Map.addLayer(myAngle)
Step 6: use the inspector to check the angles.
Step 7: remove the lines of step 5 and add the code below. Fill in the range of angles at the ??.
// add vizualization parameters var vizAngle = {min:??, max:??, palette:['FFFFFF,000000']}; // imageCollection to list var mylist= mySAR.toList(500) // get the angle of first image var myAngle = ee.Image(mylist.get(1)).select("angle") // add the layer Map.addLayer(myAngle,vizAngle,"angle")
Step 8:Remove the code again and inspect the VV layer using the code below.
 // add vizualization parameters var vizVV = {min:??, max:??, palette:['FFFFFF,000000']}; // imageCollection to list var mylist= mySAR.toList(500) // get the angle of first image var myVV = ee.Image(mylist.get(1)).select("VV") Map.addLayer(myVV,vizVV,"VV")
Step 9: Remove the code again and inspect the VV layer using the code below.
 // add vizualization parameters var vizVV = {min:??, max:??, palette:['FFFFFF,000000']}; // imageCollection to list var mylist= mySAR.toList(500) // get the angle of first image var myVV = ee.Image(mylist.get(1)).select("VV") Map.addLayer(myVV,vizVV,"VV")
Step 9: Remove the code again and inspect the VV layer using the code below.
// Also add the VH layer. var vizVH = {min:??, max:??, palette:['FFFFFF,000000']}; // imageCollection to list var mylist= mySAR.toList(500) // get the angle of first image var myVH = ee.Image(mylist.get(1)).select("VH") Map.addLayer(myVH,vizVH,"VH")
Step 10: Add another image to the map.
Hint: change the number in the get(number).
Step 11: Find this the image below in the image collection and display it.
S1A_IW_GRDH_1SSV_20160714T112841_20160714T112906_012144_012D19_1856
Question 3: What problems you encounter?
3. Identify water
Step 12: Use the code below to identify water. You need to fill in the thresholds by yourself.
var mySAR = SAR.filterBounds(roi) print(mySAR) // add vizualization parameters var vizWater = {min:0, max:1, palette:['40a4df']}; // imageCollection to list var mylist= mySAR.toList(500); var myVV = ee.Image(mylist.get(1)).select("VV"); // fill out a value here: var value = ??; // water is less than this value var water1 = myVV.lt(value); var water1 = water1.updateMask(water1); // Add to map Map.addLayer(water1,vizWater,"water VV"); // get the angle of first image var myVH = ee.Image(mylist.get(1)).select("VH") var value = ??; // water is less than this value var water2 = myVH.lt(value); var water2 = water2.updateMask(water2); Map.addLayer(water2,vizWater,"water VH");
Hi
Nice work.
Can u write on how to create mask for band ‘angle’?
For exanple i want to have intensity pixels between 18 and 78 degree incidence angle..
Thanks
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The less than (.lt) and greater than (.gt) returns a boolean map which you can use with the mask statement.
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