Setup instructions

Requirements

This toolset is written for use in Linux.

You will need access to a PC or server with at least:

  • 32 GB of RAM to run SNAP.

For your images you might get away with as little as 8 GB, but in our experience 32 GB is required for reliable outputs.

Installing SNAP

SNAP is an ESA toolset used for (amongst other things) pre-processing data from Sentinel-1. SNAP for Linux can be downloaded from http://step.esa.int/main/download/.

To install SNAP, open a terminal window, change directory to the location you’d like to download SNAP (we recommend your home directory, at~/), and run the following commands:

wget http://step.esa.int/downloads/6.0/installers/esa-snap_sentinel_unix_6_0.sh
bash esa-snap_sentinel_unix_6_0.sh

…and follow the instructions. When prompted, be sure that you install the ‘snappy’ module for integration with python.

Note

If using ALOS data from ESA, make sure that your version of SNAP is at least 6.0.

It’s a good idea to increase the memory allocation to SNAP. This is controlled by the text file ~/snap/bin/gpt.vmoptions. This can be done with the following line:

echo '-Xmx32G' >> ~/snap/bin/gpt.vmoptions

For further details and up-to-date installation instructions, see the SNAP website.

Installing snappy

Snappy is a Python module that we used to extract metadata from ALOS datasets. It should work out-of-the-box following installation of SNAP, but in case not, here are some things to try:

  • Find the directory that you istalled snap (default: ~/snap), and run ./path/to/snap/bin/snappy-conf and follow the instructions it prints out.
  • Make sure that Python can find the snappy package. You can do this by moving the snappy module to your Python site-packages directory.
  • If that fails, try editing your ~/.bashrc file to include the line export PYTHONPATH=$PYTHONPATH:/PATH/TO/snappy/.
  • If still in doubt, try consulting the ESA STEP forum.

Installing approach

approach can be downloaded to a machine from its repository. To do this, open a terminal window and input:

git clone https://sambowers@bitbucket.org/sambowers/approach.git

Where do I get help?

For help installing SNAP, it’s best to refer to the ESA STEP forum. For assistance in setting up and using approach, email sam.bowers@ed.ac.uk.