# Selfie registration and search-by-id

> Register a user's selfie once, get a stable point_id, and run every later search against it at the cheaper tier.

Source: https://sightradar.com/docs/guides/selfie-registration

Search-by-image runs the model on every selfie you send. If the same person searches repeatedly (a guest refreshing their gallery, a member checking in each morning), register their selfie once and search by its id instead: no model run, and the [search-by-face-id tier](/docs/billing#tiers) at 62 credits instead of 93.

### Register the selfie

`POST /v1/collections/{id}/selfies` is Index constrained to a single face, keyed by your `userId`. `selfieId` is optional and defaults to a content hash.

```bash
curl -X POST "$SR_BASE/v1/collections/event-2026/selfies" \
  -H "Authorization: Bearer $SR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"url": "https://cdn.example.com/selfies/u_42.jpg", "userId": "u_42"}'
```

```json title="200 response"
{
  "face_found": true,
  "collection_id": "event-2026",
  "user_id": "u_42",
  "selfie_id": "9f1c…",
  "point_id": "pt_…",
  "det_score": 0.93,
  "quality_passed": true,
  "model_version": "sr-recog-1"
}
```

Store `point_id` against the user. If `face_found` is false, `reason` says why (`no_face`), and you should ask for another photo.

### Search by id

```bash
curl -X POST "$SR_BASE/v1/collections/event-2026/search-by-id" \
  -H "Authorization: Bearer $SR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"pointId": "pt_…", "limit": 50, "threshold": 0.6}'
```

The response is the same `SearchResult` shape as search-by-image. `reason: "point_not_found"` means the id does not exist in this collection, for example after the selfie was deleted.

## Make registration retry-safe

Registration is billable, and a lost response after a successful charge would leave you without the `point_id`. Send an `Idempotency-Key`: a replay of the **same** registration (same collection, `userId`, `selfieId`) returns `200` with the stored identity fields and an `Idempotent-Replay: true` header, never a second charge. Reusing a key for a different selfie returns `409`.

## Selfies are scoped to a collection

A `point_id` lives in one collection. For a user who searches several events, register once per event, or run search-by-image with the stored selfie URL for the rare cross-event case.

## Consent

Registering a selfie stores a biometric identifier of a specific, named person. Collect it for the purpose the user expects (finding their own photos), tell them how long you keep it, and delete the collection or the photo when that purpose ends. See [trust and responsible use](/trust).