insar-management-system-v2/docs/LANDSAR_DEM_PREPARATION_CONTRACT_20260618.md

LandSAR DEM Preparation Contract

Updated: 2026-06-18

Decision

LandSAR D-InSAR and LandSAR SBAS must not run directly against the full global DEM.

The maintained flow is:

1. Convert the global DEM once into an uncompressed Int16 GeoTIFF.
2. Configure LandSAR with that global Int16 GeoTIFF as the DEM source.
3. Before each LandSAR task executes, crop a task-level DEM from the global Int16 source.
4. Write the task-level crop path into 200014.txt or 280039.txt.

The global Int16 file is a reusable source DEM. The actual LandSAR console input is the small crop stored under the run work directory.

Paths

Prepared global DEM source:

D:\DEM\SRTMDEM_RSP_SARscape_global_int16.tif

Runtime task crop location:

<run work root>\...\dem_crop\<task>_<bbox-hash>_dem.tif

Production configuration:

LANDSAR_DEM_PATH=D:\DEM\SRTMDEM_RSP_SARscape_global_int16.tif
LANDSAR_SBAS_DEM_PATH=D:\DEM\SRTMDEM_RSP_SARscape_global_int16.tif

Commands

One-time global conversion:

Set-Location D:\Code\Insar_management_system_v2; & C:\ProgramData\anaconda3\envs\InSAR\python.exe scripts\prepare_landsar_dem_int16.py --source D:\DEM\SRTMDEM_RSP_SARscape.wgs84 --target D:\DEM\SRTMDEM_RSP_SARscape_global_int16.tif --block-size 1024 --overwrite

Optional manual crop test from the prepared global GeoTIFF:

Set-Location D:\Code\Insar_management_system_v2; & C:\ProgramData\anaconda3\envs\InSAR\python.exe scripts\prepare_landsar_dem_int16.py --source D:\DEM\SRTMDEM_RSP_SARscape_global_int16.tif --crop-only --bbox 120,42,136,54 --target D:\DEM\landsar_prepared\SRTMDEM_RSP_SARscape_ne_china_int16.tif --block-size 2048 --overwrite

The manual crop command is for verification or emergency operation. Normal D-InSAR/SBAS production performs task-level cropping automatically.

Guardrails

• LANDSAR_DEM_PATH and LANDSAR_SBAS_DEM_PATH point to the global prepared Int16 GeoTIFF source.
• D-InSAR derives the crop bbox from master/slave LT-1 XML corner coordinates.
• LandSAR SBAS derives the crop bbox from all selected Input_Data LT-1 XML corner coordinates.
• The crop bbox is expanded by a margin before writing the task DEM.
• The source DEM must be Int16; Float/ENVI sources are rejected at runtime.
• Each crop writes a JSON manifest next to the crop tif.
• Run metadata records both dem_source_path and the actual task dem_path.