> For the complete documentation index, see [llms.txt](https://docs.vida.id/identity-stack/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.vida.id/identity-stack/verify/liveness/overview/zoom-liveness.md).

# Zoom Liveness

VIDA’s Zoom-based Liveness Detection adds an extra layer of security by leveraging real-time depth and motion analysis. This mode ensures that the user is physically present and responsive, reducing the risk of spoofing via static images or pre-recorded videos. 

VIDA Active Liveness offers zoom gestures along with gestures like smiling, blinking, and head shaking, further enhancing the system's ability to verify the user's presence. Users are prompted to act like blinking, smiling, or turning their heads. The system verifies that the user's responses to prompts are timely and match expected patterns. 

### Supported Gestures

VIDA active liveness detection incorporates basic gestures to ensure user authenticity. \
\
These gestures are categorized into two distinct sets. Actions from one set cannot be combined with actions from the other set. If no gesture is specified when active liveness is enabled, the ZOOM\_FACE gesture set will be used by default.

* `ZOOM_FACE` : When the gesture is set to ZOOM\_FACE, the user is prompted to adjust their face within three consecutive, randomly-sized concentric frames.
* `SMILE/ BLINK/ SHAKE_HEAD` : Users respond to prompts for smiling, blinking, and head shaking, with VIDA analyzing these actions to confirm they are genuine and appropriate.

<table><thead><tr><th width="178.0703125">Gesture</th><th width="284.125">Description</th><th>Representation</th></tr></thead><tbody><tr><td>Head Shake Movements</td><td>Users are prompted to shake their heads. VIDA detects if the head shake is matching expected patterns.</td><td><div><figure><img src="/files/aMabtNiYyPfn6EVegEhY" alt="" width="141"><figcaption></figcaption></figure></div></td></tr><tr><td>Blink</td><td>Users are prompted to blink. VIDA detects if the head shake is matching expected patterns.</td><td><div><figure><img src="/files/xAlpsh2Usp68P3N0Y5h1" alt="" width="141"><figcaption></figcaption></figure></div></td></tr><tr><td>Smile</td><td>Users are prompted to smile. VIDA detects if the head shake is matching expected patterns.</td><td><div><figure><img src="/files/3sEJ24vwdmyQPndkmADE" alt="" width="142"><figcaption></figcaption></figure></div></td></tr></tbody></table>

### Product Configuration Recommendation

| Gesture Combination | Case                                                                                                                                                                                                                                                                     | Example                                                                                   |
| ------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------- |
| **Zoom Gesture**    | Zoom gesture offers the highest level of security by analyzing depth and detailed facial features. It's ideal for high-security environments where preventing fraud is critical. This gesture is harder to spoof and provides a robust defence against advanced threats. | The user is prompted to come closer to the frame, and repeated for different frame sizes. |

### **How It Works**

The user is prompted to adjust their face within three consecutively appearing concentric frames of varying sizes. This zoom-in gesture mimics natural movement and depth changes, which are validated in real time by the SDK.

### **Gesture Validation**

The SDK analyses facial motion and alignment as the user moves their face closer or further from the camera. Only after successful validation of the zoom gesture does the SDK proceed to the liveness verification stage.

### **Benefits**

* Adds motion-based depth analysis for spoof resistance
* Simple and intuitive for users to follow
* Effective against printed photos and screen replays