---
title: "Terrain-derived analysis"
method: GET
path: "/api/v1/terrain"
---

# Terrain-derived analysis

`GET /api/v1/terrain`

## Request

- Base URL: `https://offnadir-delta.com`
- URL: `https://offnadir-delta.com/api/v1/terrain`
- Auth: one of:
  - HTTP bearer
  - API key in header `X-API-Key`

Free. Two computations derived from the Copernicus DEM GLO-30, both returned from a single read. `operation=sar_geometry` over a bbox, with `incidence_deg` and `look_azimuth_deg`, returns the share of the area lost to LAYOVER and SHADOW, the share merely foreshortened, and the mean local incidence angle — the arithmetic behind whether radar can actually use that ground, which changes with the pass direction and must not be assumed. `operation=profile` between two points returns the ground along the line and a LINE-OF-SIGHT verdict including Earth curvature: where the terrain first rises above the sight line, and by how much at worst. Both state the sample spacing they were computed at, because a coarser grid reads flatter and therefore more observable than the ground is. A SURFACE model, so canopy and buildings are included. Cite the returned attribution.

## Query parameters

- `operation` 'sar_geometry' | 'profile', required
- `bbox` string
- `incidence_deg` number
- `look_azimuth_deg` number
- `lat` number
- `lon` number
- `to_lat` number
- `to_lon` number
- `observer_height_m` number

## Response `200`

The requested terrain computation.

- object
  - `operation` string
  - `sar_geometry` object: Present for operation=sar_geometry.
  - `profile` object: Present for operation=profile, including line_of_sight.
  - `attribution` string

---

[API](https://skmtc.dev/offnadir-delta/apis/off-nadir-delta-api.md) · [All operations](https://skmtc.dev/offnadir-delta/apis/off-nadir-delta-api/llms.txt) · [OpenAPI document](https://skmtc.dev/offnadir-delta/apis/off-nadir-delta-api/revisions/5cf3f2bed5a2?raw)