> For the complete documentation index, see [llms.txt](https://docs.unitlab.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.unitlab.ai/documentation/multimodal-annotations/multi-camera-video.md).

# Multi-camera video

Multi-camera annotation keeps several views of one event together while preserving the perspective of each camera. Use a Data Group and a deliberate layout so annotators can maintain object identity, compare occlusion, and review geometry without opening unrelated tasks.

## See multi-camera annotation

{% embed url="<https://homepage-files.s3.us-east-2.amazonaws.com/hero-videos/hero/multimodal-1.mp4>" %}

![Four synchronized camera views with perspective-aligned cuboids](/files/j3bcITcPmAT1cxWXFXSv)

*Each tile represents its own camera perspective; the Data Group represents the shared event.*

## Design the group before annotation

Define:

* the file or camera naming rule;
* the grouping key that identifies one shared event;
* one tile per expected camera or sensor;
* the layout and tile order;
* whether timestamps are synchronized exactly or within a documented tolerance;
* the object-identity policy across views;
* the ontology geometry and properties required per view;
* the review route for missing, late, corrupted, or unsynchronized feeds.

Use [Data Groups and layouts](/documentation/data/data-groups-and-layouts.md) to create or audit the groups before attaching them to a project.

## Annotate one event

{% stepper %}
{% step %}

#### 1. Open the grouped item

Confirm the group identity, expected camera tiles, timestamps, and current workflow stage. Missing or duplicate views should be resolved before labeling.
{% endstep %}

{% step %}

#### 2. Choose the active camera

Activate the view with the clearest seed geometry. Passive views remain visible for identity and occlusion context.
{% endstep %}

{% step %}

#### 3. Create the annotation

Select the ontology class and draw the required box, mask, polygon, keypoints, skeleton, or cuboid in the active view.
{% endstep %}

{% step %}

#### 4. Compare sibling views

Inspect the same object in the other cameras. Preserve shared identity according to the project rule while keeping perspective-specific geometry distinct.
{% endstep %}

{% step %}

#### 5. Review time and occlusion

Scrub synchronized video where available. Check entrances, exits, occlusion, reappearance, camera delay, track continuity, and dynamic properties.
{% endstep %}

{% step %}

#### 6. Save and route the group

Resolve required values and issues, save the active annotation state, and submit the grouped work item through the configured review stage.
{% endstep %}
{% endstepper %}

## Quality controls

| Review focus    | Production guidance                                                                           |
| --------------- | --------------------------------------------------------------------------------------------- |
| Synchronization | Define and test timestamp tolerance before production.                                        |
| Identity        | One real object should keep the intended cross-view identity.                                 |
| Geometry        | Do not copy perspective-specific coordinates directly between cameras.                        |
| Missing views   | Surface absent or corrupted feeds as an explicit group state.                                 |
| Delivery        | Preserve group membership, tile role, camera identity, time basis, and annotation provenance. |

{% hint style="warning" %}
A multi-camera layout provides context; it does not automatically calibrate cameras or convert one view’s geometry into another view’s coordinates.
{% endhint %}

## Next steps

* Configure the general [Multiview Workbench](/documentation/multimodal-annotations/multiview-workbench.md).
* Review [Video Annotation](/documentation/annotations/video-annotation.md) for tracking and timeline behavior.
* Use [Multimodal overview](/documentation/multimodal-annotations/multimodal-overview.md) for cross-modal groups.