# HALOWERK Europe Land – Built-Up Share (Polygon)

> HALOWERK Europe Land – Built-Up Share (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 the share of ESA WorldCover 2021 pixels classified as built-up within a user-supplied WGS84 polygon across 30 European countries.

## Facts

- Endpoint: POST https://euroland.halowerk.com/v1/europe-built-up-share-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-built-up-share-polygon-b63f81cf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WflvYzHHQwU81fqWt2kKQ

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-built-up-share-polygon-b63f81cf -d '<json body>'
```

Example prompt: What share of this parcel is classified as built-up according to ESA WorldCover? The area is bounded by coordinates [[-0.12, 51.50], [-0.11, 51.50], [-0.11, 51.51], [-0.12, 51.51]] in London.

## When to prefer this

Choose this endpoint when you need the precise built-up land cover share for a custom polygon boundary within Europe, using the authoritative ESA WorldCover 2021 dataset. Prefer it over raster download approaches when you need a single standardized scalar result without handling raw satellite imagery. Use when the analysis area can be expressed as a polygon with up to 100 vertices and a maximum span of 0.25 degrees, and when coverage of any of the 30 supported European countries is sufficient.

## Known failure modes

- Polygon spans more than 0.25 degrees — request rejected
- Polygon has fewer than 3 coordinate pairs — invalid geometry error
- Coordinates fall outside the supported European bounding box (longitude -31.5 to 40.5, latitude 34 to 72.5) — out-of-coverage error
- Polygon has more than 100 vertices — input validation failure
- Malformed coordinate pairs (wrong data type or order) — schema validation error
- Payment not attached or insufficient — 402 Payment Required

## How this service works

Share of ESA WorldCover 2021 pixels classified as built-up. The service evaluates the bounded polygon supplied by the caller and returns standardized units across all 30 covered countries.

## Output

A standardized numerical value representing the share (fraction or percentage) of pixels within the provided polygon classified as built-up by ESA WorldCover 2021, covering all 30 supported European countries.

## 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-built-up-share-polygon-b63f81cf/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)