s1_lia

s1_lia is a Python package for searching, downloading, and merging Sentinel-1 local incidence angle (LIA) files. It simplifies access to static OPERA RTC products by handling AOI validation, ASF search, reliable downloading, and data merging by relative orbit.

Features

• Validate and normalize Areas of Interest (AOI) from WKT, GeoJSON, Shapely, or GeoPandas objects.
• Search ASF for static OPERA Sentinel-1 RTC products overlapping the AOI.
• Download local incidence angle GeoTIFF files robustly with retry support.
• Merge downloaded files by relative orbit into combined GeoTIFFs.
• Generates human-readable file name stems based on AOI centroid and optional reverse geocoding.

Installation

Install via pip:

pip install s1_lia

Usage

Simple aoi designation, data search and download (packaged into get_opera_lia), and plotting to check results.

See documentation of get_opera_lia for all optional arguments including to select only a certain relative orbit and setting file names.

import s1_lia

# Define AOI as WKT polygon string
aoi_wkt = 'POLYGON((-107.5 37.6,-107.5 38.0,-108.0 38.0,-108.0 37.6,-107.5 37.6))'

# Define directory to store downloaded and merged files
data_dir = "./data"

# Run full workflow: search, download, merge
merged_files = s1_lia.get_opera_lia(aoi_wkt, data_dir)

print("Merged incidence angle files:")
for f in merged_files:
    print(f)

import xarray as xr
import shapely
import matplotlib.pyplot as plt
xr.open_dataarray(merged_files[0]).rio.reproject('EPSG:4326').plot()
x, y = shapely.from_wkt(aoi_wkt).exterior.xy
plt.gca().plot(x,y, color = 'k', linewidth = 4)

Functions

find_static_opera_files(aoi, relative_orbit=None, ...): Search ASF for matching OPERA products.

download_results(results, data_directory, ...): Download local incidence angle files.

merge_lia_by_relative_orbit(downloaded_files, output_directory, name_stem): Merge downloaded files by relative orbit.

generate_name_stem(aoi, use_place_name=True): Generate descriptive filename stem based on AOI centroid.

get_opera_lia(...): Runs full workflow combining above steps.

Development

To install in development mode:

git clone https://github.com/zachhoppinen/s1_lia.git
cd s1_lia
pip install -e .

Run tests

pytest tests/

License

This project is licensed under the MIT License. See the LICENSE file for details.

Acknowledgments

Built on top of the ASF Search Python API.

Uses Shapely, GeoPandas, xarray, and rioxarray.

Data from: https://www.earthdata.nasa.gov/data/catalog/asf-opera-l2-cslc-s1-v1-1 https://d2pn8kiwq2w21t.cloudfront.net/documents/ProductSpec_RTC-S1.pdf

Please use citation:

NASA/JPL/OPERA. (2023). OPERA Co-registered Single Look Complex from Sentinel-1 validated product (Version 1) [Data set]. NASA Alaska Satellite Facility Distributed Active Archive Center. https://doi.org/10.5067/SNWG/OPERA_L2_CSLC-S1_V1 Date Accessed: 2025-08-08

Inspiration from: https://github.com/egagli/generate_sentinel1_local_incidence_angle_maps

Contact

For questions or feedback, open an issue or contact Zach Hoppinen @ zmhoppinen@alaska.edu

To bump version and trigger pypi upload

bump2version patch # or minor major
git push origin vx.x.x # TODO this should not be needed.