# HALOWERK Eastern Land – Croatia Depression Depth

> HALOWERK Eastern Land – Croatia Depression Depth is a paid API for AI agents from ostland.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-13).

Returns the positive elevation difference between a neighborhood mean and the center cell elevation for a given coordinate in Croatia, quantifying local topographic depression depth.

## Facts

- Endpoint: POST https://ostland.halowerk.com/v1/hr-depression-depth
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-eastern-land-croatia-depression-depth-c1e02196
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_97hoUTUbkUJGWecGhFbUW

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-croatia-depression-depth-c1e02196 -d '<json body>'
```

Example prompt: What's the depression depth at latitude 45.4 and longitude 16.8 in Croatia — basically how much lower is that point compared to the surrounding terrain elevation?

## When to prefer this

Choose this endpoint when you need a precise, per-point measure of local topographic depression depth specifically within Croatia, validated against official boundary data. It is ideal for terrain hollowness analysis, karst feature detection, agricultural drainage assessments, or flood-risk modeling workflows where Croatia-scoped geospatial accuracy and boundary enforcement are required.

## Known failure modes

- Coordinate outside Croatia's Natural Earth boundary — request rejected before payment
- Latitude or longitude outside published European coverage range (lat 34–72.5, lon -31.5–40.5) — validation error
- Non-numeric or missing coordinate fields — schema validation failure
- Center elevation higher than neighborhood mean (no depression) — may return zero or null
- Network timeout or service unavailability — HTTP 5xx error

## How this service works

Positive difference between the neighborhood mean and center elevation. The coordinate is validated against the Natural Earth boundary for Croatia; results outside it are rejected before payment.

## Output

A numeric value representing the positive difference (in meters) between the neighborhood mean surface elevation and the center cell elevation at the queried coordinate. If the coordinate falls outside Croatia's Natural Earth boundary, the request is rejected without processing.

## 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-croatia-depression-depth-c1e02196/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)