In computer graphics, a T-spline is a mathematical model for defining freeform surfaces.
To represent a three-dimensional solid object, or a patch of one, B-Spline or NURBS curves are extended to surfaces.
Modeling surfaces with T-splines can reduce the number of control points in comparison to NURBS surfaces and make pieces easier to merge, but increases the book-keeping effort to keep track of the irregular connectivity.
To smoothly join at points where more than three surface pieces meet, T-splines have been combined with geometrically continuous constructions of degree 3 by 3 (bi-cubic)[4] and, more recently, of degree 4 by 4 (bi-quartic).
Polygon meshes can represent exact intersections but lack the shape quality required in industrial design.
Pixar's variant of the subdivision surfaces has the advantage of edge weights.