# L2 Global ReLocalization Component

## Detailed Description
**L2 Global ReLocalization** addresses the "Kidnapped Robot" problem. It is triggered when L1 fails (tracking lost) or periodically to drift-correct. It uses **AnyLoc (DINOv2 + VLAD)** to describe the current UAV image and queries the **Map Data Provider's** Faiss index to find the most similar satellite tiles.

It does NOT give a precise coordinate, but rather a "Top-K" list of candidate tiles (coarse location).

## API Methods

### `localize_coarse`
- **Input:** `frame: FrameObject`, `top_k: int`
- **Output:** `List[CandidateLocation]`
- **Description:**
    1. Runs DINOv2 inference on the frame to get feature map.
    2. Aggregates features via VLAD to get a global descriptor vector.
    3. Queries Map Data Provider's Global Index.
    4. Returns list of candidates.
        - **CandidateLocation:** `{ tile_id: str, similarity_score: float, center_gps: LatLon }`
- **Test Cases:**
    - Input Frame A -> Returns Satellite Tile covering Frame A's location in Top-3.
    - Input Black/Occluded Image -> Returns Low confidence or random.

## Integration Tests
- **Recall Test:** Run on dataset where ground truth is known. Verify that the correct tile is within the returned Top-5 for > 80% of queries.

## Non-functional Tests
- **Query Time:** Vector search must be extremely fast (< 50ms) even with large indices. DINOv2 inference is the bottleneck.