In a lofted surface, two bounding entities are defined to patch a surface between them. A lofted surface is a linear surface and is created by linear interpolation between the boundary surface.

It is bounded by two arbitrary curves denoted by $P(u, 0)$ and $P(u, 1)$ and and by two segments $P(0, v)$ and $P(1, v)$ connecting them.

Surface line in the v direction are straight. Therefore surface is created by linearly interpolating between the boundary surface.

$P(u, v)=(1-v) P(u, 0)+v P(u, 1)$