> For the complete documentation index, see [llms.txt](https://doc.ozforensics.com/oz-knowledge/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.ozforensics.com/oz-knowledge/guides/developer-guide/api/oz-api/basic-scenarios/biometry.md).

# Biometry (Face Matching)

The Biometry algorithm is intended to compare two or more photos and detect the level of similarity of the spotted faces. As a source media, the algorithm takes photos, videos, and documents (with photos).

### Requirements

1. You're [authorized](/oz-knowledge/guides/developer-guide/api/oz-api/use-cases/authentication.md).
2. You have already [created a folder and added your media](/oz-knowledge/guides/developer-guide/api/oz-api/use-cases/uploading-media.md) marked by correct tags into this folder.

### Processing steps

1\. Initiate the analysis for the folder: `POST /api/folders/{{folder_id}}/analyses/`

If you want to use a webhook for response, add it to the payload at this step, as described [here](/oz-knowledge/guides/developer-guide/api/oz-api/use-cases/using-a-webhook-to-get-results.md).

{% code title="request body" %}

```javascript
{
  "analyses": [{
    "type": "biometry",
    // optional; omit to include all media from the folder
    "source_media": [
      "1111aaaa-11aa-11aa-11aa-111111aaaaaa", 
      "2222bbbb-22bb-22bb-22bb-222222bbbbbb" 
      ]
  }]
}
```

{% endcode %}

You'll need`analysis_id` or `folder_id` from response.

2\. If you use a webhook, just wait for it to return the information needed. Otherwise, initiate polling:

* `GET /api/analyses/{{analysis_id}}` – for the `analysis_id` you have from the previous step.
* `GET /api/folders/{{folder_id}}` – for all analyses performed on media in the folder with the `folder_id` you have from the previous step.

Repeat until the `resolution_status` and `resolution` fields change status to any other except `PROCESSING`, and treat this as a result.


---

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