Snaphu Data Export | ![]() |
It is strongly advised before executing graph for exporting NEST data for SNAPHU processing for user to get familiar with general principles of doing phase unwrapping in NEST.
The main purpose of SNAPHU data export functionality is three-fold:
The export graph is visualized in the figure below.
In the export graph, there are two readers, and two writers. The argumentation for two readers is, that as input for SNAPHU export operation both Interferometric, and Coherence product are needed. The interferometry product is needed for the metadata and (complex) phase, while the coherence product is required for the coherence information that is used for weighting in the process of unwrapping. The reason for two writers is, that one writer saves the phase product that, as already introduced, serves as a container for the data exchange with SNAPHU, especially in the data ingestion step. While the other writer saves (exports) the data and builds a configuration file for SNAPHU software.
Part indicated in the blue box in the figure bellow performs the following:
Branches groupd by the red box in the figure bellow performs the following:
Given that the SNAPHU software is properly installed and configured, unwrapping of exported NEST product is quite straightforward. In the directory where the SNAPHU product is being saved, the following command is to be executed:
snaphu -f snaphu.conf YOUR_PHASE_BAND.img 99999
where YOUR_PHASE_BAND.img
stands for the name of the phase band that is to be unwrapped, and
99999
represents the number of lines of the YOUR_PHASE_BAND
. Note
that
the command to be externally called for the phase unwrapping is listed in the header of snaphu.conf
file
that is created with the SNAPHU writer.
Again, it is strongly recommended that before doing any processing with SNAPHU user becomes familiar with the software and process control flags.