# HALOWERK Europe Land – Bilinear Surface Elevation (Polygon)

> HALOWERK Europe Land – Bilinear Surface Elevation (Polygon) is a paid API for AI agents from euroland.halowerk.com, paid per call via x402, $0.006/call, status unknown (last checked 2026-09-15).

Returns bilinear-interpolated surface elevation statistics from Copernicus DEM GLO-30 for a user-supplied WGS84 polygon across 30 European countries.

## Facts

- Endpoint: POST https://euroland.halowerk.com/v1/europe-elevation-parcel
- Price: $0.006/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-europe-land-bilinear-surface-elevation-polygon-048ddbf8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_SbTEFQObbsIVFYTpoLBQo

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability halowerk-europe-land-bilinear-surface-elevation-polygon-048ddbf8 -d '<json body>'
```

Example prompt: What is the surface elevation for this parcel in France — the polygon corners are at [2.35, 48.85], [2.36, 48.85], [2.36, 48.86], [2.35, 48.86]?

## When to prefer this

Choose this endpoint when you need Copernicus GLO-30 bilinear elevation for a specific polygon boundary in Europe (up to 0.25° span) rather than a circular buffer or point lookup. It is the right choice for parcel-level, property, or site-boundary elevation queries across the 30 supported European countries where standardized DEM data is required.

## Known failure modes

- Polygon outside the 30 covered European countries — service returns an error or no data
- Polygon span exceeds 0.25 degrees — request rejected
- Fewer than 3 coordinate pairs supplied — invalid polygon error
- Coordinates outside WGS84 bounds (lon -31.5 to 40.5, lat 34 to 72.5) — out-of-range error
- Payment not processed — x402 payment required response
- Malformed coordinate array — schema validation failure

## How this service works

Bilinear surface elevation from Copernicus DEM GLO-30. The service evaluates the bounded polygon supplied by the caller and returns standardized units across all 30 covered countries.

## Output

A standardized elevation value (in metres) derived via bilinear interpolation from Copernicus DEM GLO-30 for the area enclosed by the submitted polygon. The response reflects the surface elevation across the parcel geometry.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "polygon": {
   "type": "array",
   "items": {
    "type": "array",
    "items": [
     {
      "type": "number",
      "maximum": 40.5,
      "minimum": -31.5
     },
     {
      "type": "number",
      "maximum": 72.5,
      "minimum": 34
     }
    ],
    "maxItems": 2,
    "minItems": 2,
    "additionalItems": false
   },
   "maxItems": 100,
   "minItems": 3,
   "description": "WGS84 polygon ring. The closing coordinate is optional; maximum span is 0.25 degrees."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-europe-land-bilinear-surface-elevation-polygon-048ddbf8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from euroland.halowerk.com](https://www.zero.xyz/host/euroland.halowerk.com/llms.txt)