Deal with Arbitrary Field Layout
===================================

.. figure:: res/arbitrary/input.png
    :align: center

    Example of an arbitrary layout

An arbitrary field layout is a type of plot arrangement that 
there's no consistant number of plots exisitng in a row/column.
To deal with such scenario, users have to additionally 
assign centroids for the extra plots. Make sure **every plot** in the 
image get assigned a centroid, and it's ok to have some centroids 
occupying empty space without plot. 

.. figure:: res/arbitrary/centroid.png
    :align: center

    The way to define centroids for an arbitrary layout


.. figure:: res/arbitrary/seg.png
    :align: center

GRID will automatically detect whether the centroid has plot occupied or not,
shrinking the space of the empty spots and 
expanding borders for ones that really cover plots.