NURBS

NURBS, which stands for non-uniform rational basis spline, is a highly precise method for creating curved surfaces within computer modeling and Computer Aided Design (CAD) applications. As opposed to 3D polygon mesh models that use points and faces to define an object in 3D space, with NURBS, a surface can be defined in 3D space using spline shapes.

The history of NURBS can be traced back to manual design processes in marine and car manufacturing, which required some ingenious ideas when needing, for example, to create accurate curves on boat designs. As technology advanced, the process of creating spline shapes was transferred to computers and became a feature of CAD and other 3D design applications. Here we have some examples of 3D models created with spline shapes and saved to the STEP format:

A small cog designed using the STEP format

Another detailed gear saved as a STEP file

A smooth, curved surface is demonstrated in the 3D bowl model

Several 3D modeling and CAD file formats are either based on or support the use of NURBS. Formats such as 3DM, STEP and others can be used to create NURBS-based 3D models. The main advantage of the NURBS approach compared to a triangle-mesh-based model is that there is no loss in detail or precision when enlarging or zooming in on sections of the model.