A D-NURBS surface has a similar structure to the curve. Proceeding analogously from (2), we define
Again, the control points and weights comprise the generalized coordinates and are assembled into vectors , , and . Two subscripts are now associated with the generalized coordinates, reflecting the surface parameters u and v. For concreteness, we order the components in these vectors such that the second subscript varies faster than the first, although this convention does not affect the derived results.
As before, we can write instead of . By analogy to in (4) and (6), we obtain for the D-NURBS surface
However, the contents of the Jacobian differ from those in the curve case. To arrive at an explicit expression for , let , for , and , be a diagonal matrix whose entries are
and let the 3-vector
As before, the and are assembled into and , respectively. Hence,
Note that is now a matrix.