isce-framework / isce-framework/isce3
Incorrect ellipsoid metadata for LAEA Europe projection
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- Dominant language
- Python
- Stars
- 239
- Forks
- 90
- Avg merge
- 13d 1h
- Merged PRs (30d)
- 5
Description
The set_get_geo_info() function is responsible for populating NISAR L2 HDF5 products with some attributes describing the coordinate reference system (CRS) of the raster grid(s) in the product.
In the implementation, some of the attributes are dependent on the EPSG code of the coordinate reference system, but three attributes related to the ellipsoid are always assumed to be WGS 84, regardless of the CRS:
However, one of the CRSes implemented by this function is LAEA Europe (EPSG:3035). The reference ellipsoid used by this coordinate system is *not* WGS 84. It uses the GRS80 reference ellipsoid, which has a different inverse flattening.
EPSG:3035 is not implemented elsewhere in ISCE3. We should remove support for it in this function (or else correctly populate the ellipsoid metadata).
Contributor guide
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Research direction
Start in python/packages/nisar/workflows/h5_prep.py at set_get_geo_info(), especially the ellipsoid metadata around lines 781–783 and the EPSG:3035 handling near lines 840–841. Verify how LAEA Europe is represented and finish by either removing EPSG:3035 support or populating its GRS80 ellipsoid metadata correctly.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- data
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100