What is a ʼLoftʼ operation in Rhino?

Short Answer

A Loft operation in Rhino creates a surface or polysurface that smoothly spans between two or more profile curves using the Loft command. It’s the most common professional method for building transitional forms from section curves. Limitation: Loft quality depends heavily on clean, well-aligned input curves.

What You Need to Know Before

Warning: If your section curves have mismatched directions, different seam locations, or inconsistent point structures, Rhino can generate a twisted or uneven loft. This is especially common with closed curves and often goes unnoticed until later surfacing or trimming fails.

How to Do It

• Command: Loft

• Shortcut: Loft

• Quick Steps:

  1. In the viewport, select the profile curves in order, then run Loft from the Surface menu or type Loft in the command line.
  2. In the Loft options, choose a common method such as Normal and check curve direction if Rhino previews a twist.
  3. Set options like Closed Loft or adjust Rebuild with ___ control points if needed, then press Enter to create the surface.

Variables & Settings

• Key Setting: Style / Loft Type

  This option controls how Rhino interpolates between the selected section curves. Normal is the most common professional choice for general surfacing, while Loose, Tight, and Straight sections change how closely the loft follows the curve shapes.

Why it Fails

• Cause 1 (Geometry): Curves are selected out of sequence, have reversed directions, or closed curves have mismatched seams, causing twists or pinching.
• Cause 2 (layers/Locks): One or more section curves are on a locked layer, hidden layer, or are accidentally unselectable, so the loft chain is incomplete.
• Cause 3 (Command/Logic): Loft is being used where section curves differ too drastically, creating a poor surface that should have been built with Sweep, NetworkSrf, or Patch instead.

Quick Fix & Best Practice

• Quick Fix: Run Dir to check curve directions and adjust closed-curve seams before using Loft again.
• Manager’s Verdict: Use Loft for clean transitional surfaces between ordered section curves, but avoid it for complex multi-directional shapes where Sweep 2 or NetworkSrf gives better control.

FAQ

Can Loft work with closed curves?

Yes, but seam alignment must be managed carefully to avoid twisting.

Does Loft create a solid in Rhino?

Only if the input curves and options produce a closed volume or are later capped/joined.

What is the difference between Loft and Sweep in Rhino?

Loft uses section curves only, while Sweep uses one or more rail curves to control the surface path.

.