# HALOWERK Eastern Land – Bulgaria Surface Elevation

> HALOWERK Eastern Land – Bulgaria Surface Elevation is a paid API for AI agents from ostland.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-15).

Returns bilinear-interpolated surface elevation for a WGS84 coordinate within Bulgaria, sourced from the Copernicus DEM GLO-30 dataset.

## Facts

- Endpoint: POST https://ostland.halowerk.com/v1/bg-elevation
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-eastern-land-bulgaria-surface-elevation-4540caec
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_eGMfzRyFoEaucrIr90M-6

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-eastern-land-bulgaria-surface-elevation-4540caec -d '<json body>'
```

Example prompt: What is the surface elevation at latitude 42.698 and longitude 23.322 in Bulgaria, using the Copernicus GLO-30 DEM?

## When to prefer this

Use this endpoint when you need high-resolution (GLO-30, ~30 m) surface elevation for a specific point within Bulgaria and want coordinate pre-validation to avoid wasted calls. Prefer it over generic elevation APIs when you specifically need Copernicus DEM data for Bulgarian territory with per-call micropayment pricing.

## Known failure modes

- Coordinate outside Bulgaria boundary — rejected with an error before payment is processed
- Coordinate within the European coverage bounding box but outside Bulgaria — validation failure
- Latitude or longitude out of the accepted European range (lat 34–72.5, lon −31.5–40.5) — input validation error
- Network or service timeout
- Payment failure via x402 protocol

## How this service works

Bilinear surface elevation from Copernicus DEM GLO-30. The coordinate is validated against the Natural Earth boundary for Bulgaria; results outside it are rejected before payment.

## Output

Returns a single bilinear-interpolated elevation value (in metres above sea level) for the queried WGS84 coordinate derived from the Copernicus DEM GLO-30 raster. Coordinates outside the Bulgaria boundary are rejected before any charge is applied.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "latitude": {
   "type": "number",
   "maximum": 72.5,
   "minimum": 34,
   "description": "WGS84 latitude inside the published European coverage."
  },
  "longitude": {
   "type": "number",
   "maximum": 40.5,
   "minimum": -31.5,
   "description": "WGS84 longitude inside the published European coverage."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-eastern-land-bulgaria-surface-elevation-4540caec/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from ostland.halowerk.com](https://www.zero.xyz/host/ostland.halowerk.com/llms.txt)