Time_Series_Processing_SBAS

This page covers the necessary set up and details for running the time series processing of batch unwrapped interferograms, using the sbas software.

Setting Up to Run SBAS

Prepare the Input Files

First, you need to prepare the scene.tab and intf.tab files for running sbas. To do this you can use the tool prep_sbas.csh as long as you have your intf.in and baseline_table.dat files handy.

# this assumes your unwrap.grd and corr.grd files are in ../merge/"date1_date2"/
prep_sbas.csh intf.in baseline_table.dat ../merge unwrap.grd corr.grd

This will produce the scene.tab files (the list of dates in your time series) and the intf.tab file (the list of interferogram phase and correlation files to be used in SBAS). It will also output a basic/default sbas command structure for you.

Running SBAS

Once you have your input files set up, you need to choose your sbas flags to produce the time series calculation you want (see the sbas page for descriptions).

Note that when you run sbas your machine will need a certain amount of memory to handle the calculation. The -mmap flag can help, but it will take longer to run. If you need to reduce the size of the calculation, you can choose to downsample your input phase and correlation grids to a lower resolution.

Running in parallel

There is an option to run sbas in parallel (see sbas_parallel) if you have GNU parallel installed and if you have compiled the sbas_parallel program (see https://github.com/gmtsar/gmtsar/wiki/Compile-parallel-sbas-code for instructions).

When sbas finishes, there should be a cumulative displacement grid (disp_xxxxxxx.grd) for every date in your scene.tab file, a velocity grid (vel.grd), a DEM error grid (dem.grd, if you chose to output one), and an RMS misfit grid (rms.grd, if you chose to output one).

To extract a point time series from these grids, check out extract_one_time_series.csh.