# HALOWERK Eastern Land – Bulgaria Terrain Aspect

> HALOWERK Eastern Land – Bulgaria Terrain Aspect 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 the circular direction of the dominant surface gradient (aspect) at a given coordinate, clockwise from north, validated against Bulgaria's boundary.

## Facts

- Endpoint: POST https://ostland.halowerk.com/v1/bg-aspect
- 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-terrain-aspect-b4aa5539
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__qkNUK1deisrmaBgWbEwJ

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-terrain-aspect-b4aa5539 -d '<json body>'
```

Example prompt: What direction does the terrain face at latitude 42.15, longitude 24.75 in Bulgaria — give me the aspect angle clockwise from north.

## When to prefer this

Choose this endpoint when you need terrain aspect (slope-facing direction) specifically for coordinates within Bulgaria, and want boundary validation before incurring payment. Prefer this over generic DEM APIs when you need a lightweight, pay-per-call micro-service focused on Bulgarian land coverage with built-in coordinate validation.

## Known failure modes

- Coordinate outside Bulgaria's Natural Earth boundary — request rejected with error before payment
- Latitude or longitude out of the accepted European coverage range (lat 34–72.5, lon -31.5–40.5) — validation error
- Invalid or missing coordinate fields — schema validation failure
- No terrain data available for the given coordinate — possible no-data response

## How this service works

Circular direction of the dominant surface gradient, clockwise from north. The coordinate is validated against the Natural Earth boundary for Bulgaria; results outside it are rejected before payment.

## Output

A numeric value representing the clockwise angle in degrees from north (0–360) indicating the direction of the dominant surface gradient at the queried coordinate. Points outside Bulgaria's Natural Earth 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-terrain-aspect-b4aa5539/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)