Figure 2: (a) The endocardial surface (green) shown with the curve (orange) and associated cylinder that approximates the surface. (b) The curve (orange) and a discrete sampling of the outward-pointing unit normal vector (black) to the curve shown alongside the induced vector field (blue). (c) The induced curvilinear coordinate system. Plot shows lines of constant (solid black), lines of constant (dashed black), an individual solution trajectory for (dashed blue), and the original curve (orange).