Test Blocks: Examples
---------------------

To illustrate the logical of IntPhys, we provide 4 examples of test blocks, each
one being devoted to a particular principle of intuitive physics. A more
complete list of blocks is to be found in the :ref:`future` page.

.. note::

   The test dataset is available at the :ref:`download` page.


Block O1: object permanence
~~~~~~~~~~~~~~~~~~~~~~~~~~~

This block tests wether a vision system has object permanence, that is, the
principle that macroscopic objects dont pop in and out of existence. The
computational challenge of this block is to achieve multi-object tracking
through (some times rather long) occlusions.

The events are either occluded or visible, and the timing of the occlusion and
objects motions is varied randomly from case to case, making it difficult to
rely on simple tricks to discriminate between possible and impossible events.


* Examples of possible events

  .. image:: ../../data/examples/O1_d2_o/possible.gif
     :width: 650 px


* Examples of impossible events

  .. image:: ../../data/examples/O1_d2_o/impossible.gif
     :width: 650 px


Block O2: shape constancy
~~~~~~~~~~~~~~~~~~~~~~~~~

This block tests wether a vision system has shape constancy, that is, the
principle that (solid) macroscopic objects keep they overall shapes (even though
they may change their appearance. The computational challenge of this block is
to achieve multi-object tracking through changes in appearance and/or partial
occlusion.


* Examples of possible events

  .. image:: ../../data/examples/O2_s_o/possible.gif
     :width: 650 px


* Examples of impossible events

  .. image:: ../../data/examples/O2_s_o/impossible.gif
     :width: 650 px


Block O3: spatio-temporal continuity
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This block tests wether a vision system encodes spatio-temporal continuity, that
is, the principle that macroscopic objects cannot teleport across space without
going to all of the intermediate steps. The computational challenge of this
block goes beyond standard object tracking and requires to perform trajectory
prediction (in order to detect that an object tracking is anomalous).

Here, the examples are given without occluders.


* Examples of possible events

  .. image:: ../../data/examples/O3_d1_v/possible.gif
     :width: 650 px


* Examples of impossible events

  .. image:: ../../data/examples/O3_d1_v/impossible.gif
     :width: 650 px


Block O4: energy conservation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This block tests wether a vision system encodes the principle of energy (and
momentum) conservation. It states that the total energy (and momentum) of
macroscopic objects has to stay constant when there is no friction. The
computational challenge of this block requires rather precise trajectory
prediction (in order to detect that an object tracking is anomalous).


* Examples of possible events

  .. image:: ../../data/examples/O4_d1_o/possible.gif
     :width: 650 px


* Examples of impossible events

  .. image:: ../../data/examples/O4_d1_o/impossible.gif
     :width: 650 px