.. _deduplication:

Deduplicate Events
=========================

.. rubric:: In this section:

.. contents::
   :local:

Consider enabling Deduplication to exclude coinciding object recognition events within one camera group.


Enable Deduplication
--------------------------

To enable event deduplication, do the following:

#. Enable the offline video detection mode for each camera in the group. See :ref:`add-camera` for details.
#. Navigate to the :guilabel:`Preferences` tab. Click :guilabel:`Camera Groups`.
#. Open the camera group settings.
#. Check :guilabel:`Deduplicate Events` and specify the deduplication interval in seconds.

How It Works
---------------------

The deduplication algorithm works as follows. In the offline mode, the server receives one best object snapshot per tracking session on a camera.

.. note::
   A tracking session continues until an object disappears from the camera field.
 
If there are several tracking sessions on a camera(s) of a camera group within the specified deduplication interval, FindFace Multi handles the received snapshots in the following way:

* If there is a match with a dossier within the preceding deduplication interval, FindFace Multi drops a newly acquired snapshot. Otherwise, it saves the snapshot to the database.
* For unmatched objects, FindFace Multi considers both the similarity between objects and snapshot quality when performing deduplication. As a result, FindFace Multi drops all snapshots within the deduplication interval unless a new object snapshot is of higher quality. Thus, it guarantees the system deduplicates events without skipping high-quality objects, which are essential for further video analytics.