NURBS meets SubD Surfaces in a new add-on. No one product can yet do it all.

Over the years as 3D CAD has matured, a technology gap has formed and widened between specifying shapes with precision—but in a tightly constrained fashion—and the ability to model in freeform style, as with working with clay. New products are starting to come to market to bridge the gap.

The two primary technologies are NURBS (Non-Uniform Rational B-Splines) boundary representation (Brep) and SubD (Sub-Division) surface modeling. NURBS are precise but don’t work well in what-if situations such as early concept modeling. They are the primary technology for describing curves in parametric modelers such as Creo (formerly Pro/Engineer), SolidWorks, and most other 3D solid modeling CAD products. SubD is a way to represent smooth surfaces using polygon meshes, by subdividing each polygonal face into smaller faces that better approximate the smooth surface. It is the technology behind most freeform modelers used in media and entertainment design tools.

Recently we reported on new software from Luxology that bridges the gap for Modo users, and Autodesk recently bought another player in this field, T-Splines. Now there is a similar product for Rhino called Clayoo from TDM Solutions of Barcelona.

Rhino uses NURBS to describe solid models. Clayoo is a SubD surface modeler that runs inside Rhino.  TDM Solutions has created several add-ins for Rhino, primarily targeting specific design tasks such as shoe design or jewelry. Clayoo is more general purpose, for creating freeform shapes with the fluidity of SubD that can be immediately converted into the precision of a Rhino model. Once a Clayoo model is restated as a Rhino model, it can then be used in downstream applications that support NURBS surfaces and solids. As shown in the image below, Clayoo surfaces also work with Rhino’s surface analysis tools.

Clayoo allows the user to start with geometry type: solids, surfaces, meshes, or sketches. It can also be used for retopology (modification of topology) to build clean surfaces on top of poor quality imported data, such as 3D scans or STL files.

Best of both worlds

The users of 3D grahpics software are less likely today to settle for the capabilities of only one piece of software. NURBS-based 3D solid modelers were originally designed for precision in product deisgn, and it is not trivial for software vendors to add in the flexibility of freeform modeling. Working from the other way, SubD programs were built to work more like clay modeling than drafting in three dimensions. For now the  best of both worlds comes from creating best-of-breed solutions with add-in products like Clayoo. It will take next-generation development projects—and a whole lot of clever algorithmic hacks—to deliver one product that does it all.