nisarHDF

This repository contains python code to read the NISAR HDF formats and parse out the necessary parameters and reformatting necessary for the Greenland Ice Mapping Project (GrIMP) workflow. It also provides command line utilities for extracting, reformatting, and interactively viewing NISAR HDF5 data. Most of the functionality is independent of GrIMP and may prove useful for anyone working with NISAR HDF data.

Python Package

In particular, it simplifies access to NISAR data by allowing:

• Access data (e.g., myRUNW.unwrappedPhase) as numpy variables and other commonly used parameters (e.g., myGUNW.NumberRangeLooks) rather than hdf structures,
• Mask data (e.g., remove data with connected component values of zero),
• Apply ionospheric corrections to phase data,
• Interpolate metadata cubes (e.g., incidenceAngle and baseline), including mapping these variables to the same grid as the data products.
• Save data and interpolated metadata cubes to binary or geotiff files, and
• Write a .vrt file to link multiple data layers so they can be read back in as xarray.

At present classes have been developed for RSLC, ROFF, RUNW, RIFG, GOFF, GUNW, and GCOV products. A tutorial notebook for each of these data types is included in the Notebook folder of this repository.

Documentation

• Overview — package overview and class hierarchy
• BaseClasses — base HDF reader classes
• RangeDopplerProducts — RSLC, ROFF, RUNW, RIFG classes
• GeocodedProducts — GOFF, GUNW, GCOV classes
• nisarh5toimage — command-line HDF5 extraction utility
• showimage — interactive viewer for NISAR HDF5, VRT, and GeoTIFF images
• Utilities — supporting utility functions

Command line utilities

nisarh5toimage — docs

While HDF5 is a powerful format for archiving, other formats such as tiff and simple binary can be easier for many users to work with. To facilitate working with NISAR data for these users, nisarh5toimage can:

• Provide a quick summary of what's in the file (bands etc) along with essential meta data (e.g., time, orbit, frame, track, center lat/lon, etc.)
• Pull the individual bands from NISAR hdfs and write them to tiff or binary files.
• Produce an accompanying .vrt file that makes it easy to import multiband products into Python (e.g., rioxarray) or GIS packages.
• Downsample products (useful for large hi-res GCOV products).
• Produce quickLook PNG files with .vrt for geospatial information.

The nisarh5toimageTutorial notebook includes several examples of how to use this program.

showimage (new) — docs

An interactive image viewer for NISAR HDF5, VRT, and GeoTIFF files. showimage can:

• Display 1–3 images side by side with synchronized (or independent) scrolling.
• Open NISAR HDF5 products directly (RIFG, RUNW, ROFF, GUNW, GOFF, GCOV) — no intermediate conversion step needed.
• Switch between bands interactively via palette buttons, with optional band caching for fast revisits.
• Extract pixel values, column/row profiles, and line profiles interactively with click-based tools.
• Control colormap, colour range (vmin/vmax), and modulo wrapping per pane.
• Display velocity fields from two-band VRT files (--vel) with optional log-scale HSV rendering.