# HALOWERK Eastern Land – Surface Aspect (Croatia)

> HALOWERK Eastern Land – Surface Aspect (Croatia) 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), measured clockwise from north, for a given coordinate within Croatia.

## Facts

- Endpoint: POST https://ostland.halowerk.com/v1/hr-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-surface-aspect-croatia-93176d49
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_m-E5u8n1panXmeDB6JSrU

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-surface-aspect-croatia-93176d49 -d '<json body>'
```

Example prompt: What direction does the terrain face at latitude 45.32, longitude 16.18 in Croatia — 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 Croatia, particularly when boundary validation is important to avoid charging for out-of-area queries. Prefer over generic elevation APIs when you need the directional gradient rather than elevation values, and when you need the result expressed as a compass bearing in degrees.

## Known failure modes

- Coordinate outside Croatia boundary returns a rejection error before payment is processed
- Latitude or longitude outside the published European coverage range (lat 34–72.5, lon -31.5–40.5) returns a validation error
- Malformed or missing coordinate fields return a schema validation error
- Payment failure returns HTTP 402 with payment-required details

## How this service works

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

## Output

A numeric value representing the dominant surface gradient direction in degrees, measured clockwise from north (0–360°), computed for the requested coordinate within Croatia's Natural Earth boundary. Coordinates outside Croatia 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-surface-aspect-croatia-93176d49/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)