Hello
I wanted to start this conversation by suggesting that Mcneel might benefit from exploring Autodesk Alias’s approach to SubD. I think Rhino SubD has been very great tool that solves a lot of modeling problems, however, it somewhat lacks maturity and features. There’s something about Alias’s method that, in my opinion, truly stands out and could offer some insights.
What’s truly striking about Alias’s approach is its unique subdivision system. Differing from the more traditional Subdivision Tools and even from T-spline tools, which many perceive as the bridge between SubD and NURBS, Alias’s system seems to capture this middle ground more effectively. Through its use of a “Limit Surface” to depict the SubD surface, Alias has essentially integrated NURBS-like continuity. This not only lends Alias its SubD-NURBS hybrid characteristics but also allows for direct application of numerous NURBS operations – from Trims and Fillets to Blends and Offsets – right onto the SubD, bypassing any need for conversions.
Now, I’m not suggesting that Mcneel totally revamp the Subd tools. I think the Subd tools is already great but could benefit by adding features to it. I just think there are areas for improvement:
- “Box to Smooth Mode issues”
1.1 Rule of Three Method: I understand that the Rule of Three is fundamental to how NURBS curves work in Rhino, but its translation to box mode can often complicate the modeling process, especially with complex designs involving many edges. There are instances where points and edges self-intersect within the model. These can be hard to spot and result in an overall messy appearance. Perhaps a potential solution could be the integration of a feature to control the curvature through CV weights.
1.2 Inserting Edge: While inserting an edge in Rhino’s SubD usually works well, there are times when it excessively changes the curvature of the geometry. Comparatively, in Autodesk Alias, inserting an edge ensures that the model’s overall continuity remains consistent. Notably, the Box Mode in Alias remains closely aligned with the Smooth mode. In essence, the representation between these modes is consistent, without unexpected or drastic deviations of edges and points in box mode.
- Aligning/Matching Subd Edge to Curves - Now I think anyone who used T-Splines knows that it does a good job of matching a curve. Right now there seems to be 2 types of Subd Vertices, one in Box mode and one in Smooth mode.
As you can see, when I used the align command, it only aligns the Box mode Vertex -
But when in smooth mode, the desired curvature is not attained. Rhino has to align the Smooth Mode Vertex as shown. Note: I had to manually move the Smooth mode Vertex to the target curve because using the align command only aligns the Box mode Vertex.
Naturally, with this the Box mode Vertex is not aligned to the curve.
So I’ve given my two cents. I hope that this thread will be only seen as humble attempt to maybe improve Subd . Thank you 