# Halowerk Polygon Area & Centroid Calculator

> Halowerk Polygon Area & Centroid Calculator is a paid API for AI agents from geo.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-13).

Calculates the planar area and centroid of a polygon defined by a sequence of (x, y) coordinate pairs in caller-declared units

## Facts

- Endpoint: POST https://geo.halowerk.com/v1/polygon-ops
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-polygon-area-centroid-calculator-c36785fd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_f9SVuU8CuTE94bLeLPakP

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-polygon-area-centroid-calculator-c36785fd -d '<json body>'
```

Example prompt: Calculate the area and centroid of this polygon: the vertices are (0,0), (10,0), (10,5), (5,8), (0,5) — they're in meters.

## When to prefer this

Choose this endpoint when you need fast, deterministic planar polygon area and centroid computation from raw coordinate data without any geographic projection assumptions. Ideal for coordinate systems other than WGS84 (e.g. CAD units, game world units, local planar projections) where you supply your own coordinate frame. Prefer this over GIS-specific tools when you don't need reprojection and want transparent method disclosure.

## Known failure modes

- Polygon with fewer than 3 vertices returns validation error
- Coordinates outside ±1,000,000,000,000 range rejected
- Self-intersecting or degenerate polygons may produce unexpected area values
- Exceeding 100,000 vertex limit returns error
- Malformed coordinate objects missing x or y fields rejected

## How this service works

Calculates planar polygon area and centroid in caller-declared coordinate units. Missing facts are returned as null and named in unavailable_fields where applicable. Derived values disclose their method; source-backed values disclose source, time window and age. 

## Output

Returns the computed planar area of the polygon and the (x, y) coordinates of its centroid in the same units as the input. Any values that could not be computed are returned as null and listed in an unavailable_fields array. Derived values include a disclosure of the calculation method used.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "polygon": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "x",
     "y"
    ],
    "properties": {
     "x": {
      "type": "number",
      "maximum": 1000000000000,
      "minimum": -1000000000000,
      "description": ""
     },
     "y": {
      "type": "number",
      "maximum": 1000000000000,
      "minimum": -1000000000000,
      "description": ""
     }
    },
    "additionalProperties": false
   },
   "maxItems": 100000,
   "minItems": 3
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-polygon-area-centroid-calculator-c36785fd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from geo.halowerk.com](https://www.zero.xyz/host/geo.halowerk.com/llms.txt)