An Offset surface, is a smooth surface (without edges, peaks, or singular points, where each point has a tangent plane. Examples: Spheres, ellipsoids, toroids, cylinders and planes), it is defined as follows:

sd[u, v] = s[u, v] + d n[u, v] and sd[u, v] = s[u, v] - d n[u, v]

s[u, v] it is a smooth surface, d = distance, n[u, v] it is the normal unitary vector to the surface s[u, v]. In this notebook we will obtain the offset surface of the ellipsoid:

{4 Cos[u]Cos[v],3 Sin[u]Cos[v],2 Sin[v]}.