A dynamic line of action (DLOA) is

A dynamic line of action (DLOA) is a 2D parametric surface
xdloa(s; t), where t is time and s is the parameter along the line.
This surface can be displayed as a moving line by successively
showing temporal iso-lines xdloa(s; ti); i = 0:::I. In Fig. 3, we
show a visualization of the whole DLOA surface.
In this section, we discuss how such a surface can be created from
sketches: we first investigate the extension of the standard keyframing
concept to LOAs. We then introduce a new abstraction, the
space-time curve, and explain how it can be used to quickly draft
and then refine the DLOA in a principled way.
The 2D stroke the user draws is denoted C = [c0; :::; cN