Unwrapping with SNAPHU

After creating a wrapped interferogram stack, use the SNAPHU Export to prepare the data for unwrapping with SNAPHU.

The main purpose of SNAPHU data export functionality is three-fold:

To export data (bands) in the format compatible for SNAPHU processing,
To build a SNAPHU configuration file (snaphu.conf), the file where processing parameters for SNAPHU are being stored,
To construct a container product that will store metadata and bands to be used when SNAPHU results are being ingested back into the Toolbox.

Next, run SNAPHU-Unwrapping.

If SNAPHU hasn't been installed, SNAP will download and install the software on Linux and Windows. You can also download and install it yourself from http://step.esa.int/main/third-party-plugins-2/snaphu/

Select you input product and output folder and press Run to execute the SNAPHU command.

After the phase is unwrapped it can be imported to SNAP for further analysis using Radar->Interferometric->Unwrapping-> SNAPHU Import.

About SNAPHU

Two-dimensional phase unwrapping is the process of recovering unambiguous phase data from a 2-D array of phase values known only modulo 2pi rad. SNAPHU is an implementation of the Statistical-cost, Network-flow Algorithm for Phase Unwrapping proposed by Chen and Zebker. This algorithm poses phase unwrapping as a maximum a posteriori probability (MAP) estimation problem, the objective of which is to compute the most likely unwrapped solution given the observable input data. Because the statistics relating the input data to the solution depend on the measured quantity, SNAPHU incorporates three built-in statistical models, for topography data, deformation data, and smooth generic data. The posed optimization problem is solved approximately with use of network-flow techniques. As SNAPHU uses an iterative optimization procedure, its execution time depends on the difficulty of the interferogram