.. _interaction-analysis:

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Interaction Analysis
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FindFace Multi can provide interaction tracking and analysis. To harness this functionality, you must enable :ref:`face clustering <clusters>`. 

When tracking interactions, the system automatically determines a circle of people with whom a person has previously been in contact. For each person from the first circle, the system builds another circle of connected people, and so on. Overall, interaction analysis is three-circle deep.

.. note::
   You can track interactions between bodies and cars as well. Access this functionality via :ref:`HTTP API <api>`. Note that body and car clustering must be enabled beforehand.

The interaction analysis is available on the :guilabel:`Interaction Analysis` tab. 

|interaction_analysis_en|

.. |interaction_analysis_en| image:: /_static/interaction_analysis_en.png
   :scale: 50%

.. |interaction_analysis_ru| image:: /_static/interaction_analysis_ru.png
   :scale: 50%

.. tip::
   You can also display the circle of connected people right from the :guilabel:`Clusters` tab by clicking on the handshake icon.

   |clusters_handshake_button_en|

   .. |clusters_handshake_button_en| image:: /_static/clusters_handshake_button_en.png
      :scale: 60%

   .. |clusters_handshake_button_ru| image:: /_static/clusters_handshake_button_ru.png
      :scale: 60%

On the :guilabel:`Interaction Analysis` tab, click on a person to display their first circle of interactions and associated events. Keep on to unveil the entire tree of interactions.

|circles_en|

.. |circles_en| image:: /_static/circles_en.png
   :scale: 50%

.. |circles_ru| image:: /_static/circles_ru.png
   :scale: 50%


You can apply available filters to every circle.

.. tip::
   For example, you can find older adults or people without a face mask who are directly or indirectly related to a potentially contagious person.

.. tip::
   When searching through a circle of interactions, apply the following settings:

   * :guilabel:`Use the last event`: use the last event of an episode to analyze contacts between individuals. In this case, having found truly associated people is most probable as they simultaneously leave a camera’s field of view. If the option is disabled, the system will use the best event of an episode for interaction search.
   * :guilabel:`Relations threshold`: maximum time in seconds between the appearance of individuals to consider them related.
    
   |circles_configure_en|

   .. |circles_configure_en| image:: /_static/circles_configure_en.png
      :scale: 50%

   .. |circles_configure_ru| image:: /_static/circles_configure_ru.png
      :scale: 50%