Polygons & AOI

The SateAIs API uses WKT (Well-Known Text) polygons to define areas of interest (AOI).

Coordinate reference system

All polygons must use EPSG:4326 (WGS84): longitude/latitude in decimal degrees. Other CRS (UTM, Web Mercator, etc.) are not accepted.

Polygon format

Use a single WKT POLYGON with coordinates in (longitude latitude) order. The ring must be closed (first and last point identical).

POLYGON((
  139.75 35.55,
  139.80 35.55,
  139.80 35.60,
  139.75 35.60,
  139.75 35.55
))

WKT uses lon lat ordering (the opposite of GeoJSON's common [lat, lon] notation in some UIs). Double-check your inputs.

Size constraints

Detection	Polygon size limit
`ship`	No hard limit (single scene per job)
`oilslick`	No hard limit (single scene per job)
`newbuilding`	30,000 km²
`timeseries`	50 km² (approximately 7 km × 7 km)

newbuilding and timeseries enforce hard size caps at the API layer. For ship / oilslick, the polygon can be arbitrarily large — but runtime grows with area (see Recommended polling interval).

How AOI is processed

When you submit a polygon (AOI), SateAIs automatically selects a Sentinel-1 GRD scene close to date on the backend, then clips the scene to the region that intersects with your polygon. Only the intersecting portion is analyzed — coverage outside the scene footprint is skipped.

Exceeding the size cap returns 400 VALIDATION_ERROR before any credits are consumed. Split large areas into multiple jobs.

Polygon vs scene ID

For ship and oilslick, you can choose between two input patterns:

scene_id (Pattern A) — process the entire Sentinel-1 GRD scene. Use when you already know the scene or want scene-wide analysis.
polygon + date (Pattern B) — SateAIs automatically selects the nearest Sentinel-1 GRD scene for the given date and clips to the polygon. Lower credit consumption for localized analysis.

See Detection APIs for the full parameter matrix.

Sanity checks

Ensure the polygon is planar and non-self-intersecting.
Keep coordinate precision reasonable (6 decimals ≈ 0.1 m is more than enough).
If your AOI crosses the antimeridian (180°/-180°), split into two polygons.

Next steps

Detection APIs

Full parameter reference for each endpoint.