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Elevation Data & Configuration

Copernicus GLO-30 (COP30, 30 m, TanDEM-X derived) is the recommended default. Its interferometric phase center falls inside the canopy — it is neither a faithful DSM (surface, including canopy) nor a faithful DTM (bare earth). Runs should therefore be made with both:

  • GLO-30 — surface-ish, via the OpenTopography globaldem API.
  • FABDEM — bare-earth correction of GLO-30/GLO-90.

and the envelope between them reported as vegetation uncertainty. The Robustness matrix algorithm sweeps both sources automatically for exactly this reason.

FABDEM licensing

FABDEM is CC BY-NC-SA 4.0 (non-commercial) and must never be committed to this repository. Resolve licensing in writing before using it in a paid deliverable; without it, GLO-30 alone remains defensible with the limitation declared. config/jamaica.yaml's FABDEM entry is marked dev/validation-only for this reason.

DEM vertical datum

Both GLO-30 and FABDEM report elevation relative to the EGM2008 geoid. The DEM_VERTICAL_DATUM parameter on every algorithm is recorded in the manifest for traceability only — it is not used in computation, since the engine works entirely in relative heights (H_min, beam height) referenced to the radar's own antenna height h0.

Case configuration format

config/*.yaml describes one case's radars, DEM sources, importance layer, and scan parameters. See config/jamaica.yaml:

radars:
  - name: "Cooper's Hill Doppler Weather Radar, Saint Andrew Parish"
    lat: 18.07330822439374
    lon: -76.8527864446781
    ground_elevation_m: 765.6  # FABDEM bare-earth sample at this point
    tower_height_m: 30  # measured antenna height AGL, existing structure
dem:
  sources:
    - path: examples/jamaica/glo30_jamaica.tif
      label: GLO-30
      vertical_datum: EGM2008 geoid
    - path: examples/jamaica/fabdem_jamaica.tif
      label: FABDEM
      vertical_datum: EGM2008 geoid
importance_layer: null
scan:
  earth_radius_factor_k: [1.0, 1.3333, 2.0]  # normal / 4/3 / superrefractive
  tower_height_m: [10, 15, 20, 25, 30]

This file is a plan/example artifact for the Jamaica case, not yet consumed by the QGIS algorithms directly (each algorithm takes its parameters through the Processing dialog) — see notebooks/fase0_motor_horizonte_bech.ipynb for where it is read today.

Example data

examples/jamaica/ ships cropped GLO-30 and FABDEM rasters over Jamaica (south=17.65, north=18.55, west=-78.4, east=-76.2) plus a sample manifest.json, for running the notebook and the plugin against a real case without downloading data first. This extent does not cover Cuba/Haiti terrain within a 250 km radar range — traded off to keep the repository checkout small.

Effective earth-radius factor k

Standard values used across the toolkit's defaults and config/jamaica.yaml:

k Meaning
1.0 No atmospheric refraction correction
4/3 (1.3333) Standard tropospheric refraction (the conventional default)
2.0 Superrefractive conditions

k is swept, not fixed, in the Robustness matrix — the tropics can depart from the standard 4/3 assumption, and the plan treats this as a modeling uncertainty to be shown, not resolved by picking one value.