The Virtual SAR Lab

Motivation:

For many of the more involved processing labs of this class, we will be using a cloud-based Virtual SAR Lab. Using such a virtual lab has numerous advantages over physical computer pools. They come pre-installed with all relevant processing tools and spare you the painful trouble of installing each individual package by hand. In a virtual lab, all machines are identical. This ensures similar processing speed at all work stations and identical software behavior for all participants. Finally, we will ensure that all machines are correctly scaled, so that you can complete your assignments in a timely manner without ever running out of space.

Accessing the Virtual SAR Lab

The Virtual SAR Lab is implemented within the Amazon Web Services (AWS) Environment (aws.amazon.com) and ready for your use from any location. Other than universal accessibility, the advantages of a cloud-based lab environment include (1) a ready-to-use broad suite of public-domain processing tools that are available to you without requiring painful software installation; (2) a sufficiently sized processing server that can handle all processing loads related to this lab without requiring hardware purchase; (3) a set of labs and data sets at your fingertips that can be used for honing and testing your SAR processing and analysis skills.

For this course, the Virtual SAR Lab will be available to you free of charge through generous donations from the Alaska Satellite Facility (ASF) and NASA. At the end of the class, I will demonstrate to you how you can access the Virtual SAR Lab in the future (after the end of this class) through your own AWS account.

Accessing the Virtual SAR Lab – Windows

To access the Virtual SAR Lab, please use the remote access software Putty together with the X-window client VcXsrv, which can be downloaded from here:

  • Start your VcXsrv

Now launch Putty with the following settings (see Figure):

  • Host Name (in Sessions tab): You will be finding the hostname that was issued to you on Google Drive. I will inform you at the beginning of the lab where to find the information.
  • Enter the username “ubuntu” (without the quotes) in the Auto-login username field of the Connection/Data
  • Expand the Connection/SSH tab and find the Auth sub-tab. In this sub-tab, you have to link to the Private Key file for authentication, which you will receive at the beginning of the lab on a thumb drive.
  • Find the X11 sub-tab within Connection/SSH and activate the X11 forwarding radio button.
  • Finally, go back to the Session tab and save your session under a name (e.g., SERVIR-training as shown in Figure 1).
  • Click on Open to start your session.

Accessing the Virtual SAR Lab – Mac

  • Start your x-client tool
  • Copy your key file (SERVIR-key.pem) to your working directory
  • chmod 400 SERVIR-key.pem
  • ssh -X -i “SERVIR-key.pem” ubuntu@ec2-52-33-135-220.us-west-2.compute.amazonaws.com

A Look Around

The Virtual SAR Lab has the following software pre-installed:

  • MapReady (ASF)
  • ISCE and GIAnT InSAR processing tools (JPL/Caltech)
  • StaMPS InSAR processing software
  • TRAIN (Toolbox for Reducing Atmospheric InSAR Noise) tools
  • QGIS (Open source GIS client)
  • PolSARpro
  • SNAP

Beyond that, the lab holds a few scripts that will come in handy for data downloading and processing. We will talk about some of these scripts during our lab exercises.


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