insar-management-system-v2/experiments/isce2_sbas_timeseries/notes/PHASE0_REPO_READER_FINDINGS.md

Phase 0 Repo Reader Findings

Updated: 2026-04-03

Existing repo reader path

The current repository already has a stable LT-1 single-scene metadata ingestion path.

Main code path:

• backend/app/services/data_service.py
  • scan_radar_data()
• backend/app/utils.py
  • parse_lt1_radar_filename()
  • find_xml_file()
  • parse_xml_metadata()

What the existing reader does

1. Folder-name parsing

parse_lt1_radar_filename() extracts from the directory name:

• satellite
• satellite_mode
• receiving_station
• imaging_mode
• orbit_circle
• scene_center_lon
• scene_center_lat
• imaging_date
• acquisition_time_utc
• product_type
• polarization
• product_level
• product_unique_id

Example supported name:

LT1B_MONO_SYC_STRIP1_018153_E135.4_N48.3_20250701_SLC_HH_S2A_0000790171

2. XML discovery

find_xml_file() prefers:

• *.meta.xml

and falls back to:

• the only XML file in the directory, if there is just one

3. XML parsing

parse_xml_metadata() extracts:

• orbit_direction
• imaging_mode
• polarization
• receiving_station
• satellite_mode
• orbit_circle from absOrbit
• scene_center_lon
• scene_center_lat
• acquisition_time_utc
• product_type
• product_level
• product_unique_id
• look_direction
• corner coordinates and coverage polygon

4. Merge rule

scan_radar_data() merges:

• folder-name metadata
• XML metadata

with XML preferred for most fields, except product_unique_id where the folder-name value is preserved if present.

Why this matters for SBAS experiments

This means the SBAS experiment should not invent a separate metadata interpretation unless absolutely necessary.

Recommended rule:

• reuse the same field semantics already used by RadarDataORM
• reuse the same .meta.xml discovery logic
• treat scan_radar_data() output as the canonical single-scene asset layer

Data layout check against F:\Insar_data_pool_1

Sample scene directories under F:\Insar_data_pool_1 are compatible with the current single-scene reader:

• one folder per scene
• directory name matches LT-1 parser expectations
• contains *.meta.xml
• contains *.tiff
• contains preview and auxiliary files

Example sample directory:

F:\Insar_data_pool_1\LT1A_MONO_KSC_STRIP1_017030_E123.3_N46.1_20250315_SLC_HH_S2A_0000678238

Example files inside:

• ...meta.xml
• ...tiff
• ...rpc
• ...browse.jpg
• ...thumb.jpg

Practical implication

For phase 1 design and experiments:

• the current repo already knows how to ingest these LT-1 scene folders as RadarData
• stack preparation should build on top of this asset layer
• the real unknown is not scene metadata parsing
• the real unknown is how to transform these scene folders into a stack layout acceptable to stripmapStack