andard
frame</em>.</p>

<p>For example, a point $(x,y)$ can be seen as the translated version
of the origin $(0,0)$ taken as canonical point frame. Likewise, a
circle with center $(x,y)$ and radius $\sigma$ can be seen as the
translated and rescaled version of a unit circle centered at the
origin, taken as canonical circular frame.</p>

<p>In general, different classes of frames are closed under different
classes of 2D transformations. For instance, points are closed under
all transformations, while disks a