Importing results from SNAPHU processing in NEST
Important note
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.
SNAPHU Data Import Graph
The main purpose of SNAPHU data import function is two-fold:
-
To import results of SNAPHU processing in NEST,
-
To construct NEST Interferometric product that will contain unwrapped phase band, and the metadata of the source
interferometric product.
The import graph is visualized in the figure below.

In the export graph, there are two readers, and one writer. Two readers are reading the phase
product, constructed during exporting data for SNAPHU processing, and other reader
is reading imported unwrapped result of SNAPHU processing as "Generic Binary". Snaphu Import operator arranges the
metadata and bands, and constructs the unwrapped phase product compatible for further utilization within NEST. Finally,
writer saves the product in NEST/BEAM DIMAP format.
Specifically the import graph performs the following:
- 1-Read-Phase:
- Reads the "phase-only" interferometric product constructed during Snaphu Data Export step.
- 2-Read-Unwrapper-Phase:
- Reads the "unwrapped-phase-only" product ingested in NEST using Generic Binary Readers. Note that
due to restrictions of the framework currently it is not possible to chain the generic binary reader in the graph, and hence
it is not possible to ingest unwrapped data directly into NEST. This has to be done outside Snaphu Import graph.
- 3-SnaphuImport:
- Arranges the metadata and merges the bands of the source product into a unwrapped phase product. In this step
metadata and bands are arranged in a compatible form for further NEST InSAR processing.
- 4-Write:
- Writes "unwrapped phase product" in the standard NEST/BEAM DIMAP format.