Run Snap Workflow

This snippet show how to run SNAP worklows by code

Prerequisites

To run this code you need:

• A running Python 3.x Environment

• A valid WASDI Account

• A valid Config file

• A valid params.json file

If this is not clear, you probably need to take a look to the Python Tutorial before.

Recipe

Note

We will use Sentinel-1 GRD and the public LISTSinglePreproc2 workflow for this snippet, but this method can be used with any mission and any compatible workflow.

Note

Remember that you can upload in WASDI your own SNAP Workflows. For further explaination take a look here.

This is our sample params.json file.

{
    "START_DATE": "2023-01-01",
    "END_DATE": "2023-01-01",
    "BBOX": {
    "northEast": {
        "lat": 20.1,
        "lng": 44.4
        },
    "southWest": {
        "lat": 19.3,
        "lng": 43.2
        }
    },
    "MISSION": "S1",
    "PRODUCT_TYPE": "GRD",
    "WORKFLOW": "LISTSinglePreproc2"
}

# Read Bounding Box, Start and End Date
oBBox = wasdi.getParameter("BBOX", None)
sStartDate = wasdi.getParameter("START_DATE", "2023-01-01")
sEndDate = wasdi.getParameter("END_DATE", "2023-01-31")

# Read Mission and Product Type
sMission = wasdi.getParameter("MISSION", "S1")
sProductType = wasdi.getParameter("PRODUCT_TYPE", "GRD")

# Read the name of the workflow to start
sWorkflow = wasdi.getParameter("WORKFLOW", "LISTSinglePreproc2")

# Search Images
aoProductsFound = wasdi.searchEOImages(sMission, sStartDate, sEndDate, sProductType=sProductType, oBoundingBox=oBBox)

 if len(aoImagesToProcess)>0:
     # Import the first image
     wasdi.importProduct(aoProductsFound[0])

     # Get the name of the image
     sImageName = aoProductsFound[0]["fileName"]

     # In general, workflows can have multiple inputs
     asInputImages = [sImageName]

     # We need to decide the name of the output file: here you may add a more smart code (add a suffix to the original name for example)
     sOutputImage = "preprocessed.tif"

     # In general, workflows can have also multiple outputs
     asOutputImages = [sOutputImage]

     #OPTION 1: run the workflow and wait for the result
     wasdi.executeWorkflow(asInputImages, asOutputImages, sWorkflow)

     #ALTERNATIVE OPTION 2: run asynch
     sProcessId = wasdi.asynchExecuteWorkflow(asInputImages, asOutputImages, sWorkflow)
     # Here you are free to do what you want
     wasdi.wasdiLog("I started a workflow")
     # Call this if you need to wait for it to finish
     wasdi.waitProcess(sProcessId)
 else:
     wasdi.wasdiLog("No file to pre-process found")

What it does:

• Reads Input Parameters

• Starts searching for S1 GRD Images

• Runs the workflow waiting for it

• Runs the workflow without waiting for it