Curve commands have SubD friendly options, and of course, there’s a number of primitives. Surface commands such as Loft, Revolve, Sweep1, Sweep2 and Extrude, all have the option of creating SubD output.

Rhino’s new SubD objects can be created in a number of ways. This means that SubD geometry can be created accurately in Rhino and this gets over one of the major criticisms of mesh based SubD workflows that are often regarded as being approximate. So, just as with Rhino NURBS objects, they provide a continuous description of curve geometry. The new SubD objects in Rhino are spline based. So, the underlying geometry was a mesh which was smoothed to approximate a curvature continuous surface or poly-surface. These brought a SubD workflow to Rhino but crucially, these were mesh based. If you’ve been a Rhino3d user for some time, then you may be familiar with plugins such as T-Splines and Clayoo. The mesh edges are extrapolated from these vertices by tracing a straight path through pairs of points and flat mesh faces are then created between three or four mesh edges. If we look at the example of the mesh sphere, then only the mesh vertices are touching the notional sphere. Meshes on the other hand, can only approximate curve geometry. Depending on the degree and the control point layout, NURBS curves and surfaces can hold constant radii or can be used to describe curvature continuous freeform shapes. In very simple terms, NURBS surfaces can be regarded as being a continuous description of, in this case, a curved volume. If we step back to version 6, we have NURBS objects and meshes. So, first of all, what is SubD? SubD, or SubDivision surfaces are a new object type inside of Rhino. Here, I’m using a work in progress version of the software, and so some features may be further developed by the time the product ships. This is Phil at Simply Rhino, and today, I’d like to take a look at SubD modelling which is new in Rhino v7. We’ve made a transcript of the video for anyone who would like to follow the video by script. Introduction to SubD tools in Rhino v7 Video Transcript.

Watch the Introduction to SubD tools in Rhino v7 Video: The video starts by examining SubD surfaces and how these compare to NURBS before moving on to look at some examples of how and why SubD can be used alongside the traditional NURBS workflow in Rhino.

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