6 - Create Surfaces from Curves

One way of working in 3‑D is to draw curves that represent edges, profiles, cross-sections, or other surface features and then to use surfacing commands to create surfaces from those curves. Curves can be free-standing curves or the edges of existing surfaces.

Surface from edge curves

You can create a surface from three or four curves that define the edges of the surface.

Create a surface from edge curves

  1. Open the tutorial model EdgeSrf.3dm.

    (Help menu > Learn Rhino > Tutorials and Samples > User's Guide > EdgeSrf)

  2. On the Surface menu, click Edge Curves.

    Optional: Press F1 to review the Help topic for the EdgeSrf command.

  3. At the Select 2, 3, or 4 open curves prompt, select the four curves as shown in the illustration below.

    To select the curves, you can click each individual curve using the Shift key, or you can use a window or crossing selection to select all of the curves at once. To review selecting objects, see Chapter 3, Selecting Objects.A surface is created from the curves, which define its edges.

Extrude curves

Surfaces can be created by extruding curves in a straight line perpendicular to the construction plane.

Create an extruded surface

  1. Open the tutorial model ExtrudeCrv.3dm.

    (Help menu > Learn Rhino > Tutorials and Samples > User's Guide > Extrude)

  2. On the Surface menu, click Extrude Curve, and then click Straight.

    Optional: Press F1 to review the Help topic for the ExtrudeCrv command.

  3. At the Select curves to extrude prompt, select the curve (1) as shown in the illustration below.
  4. At the Extrusion distance prompt, drag a distance with your mouse and click.

Loft curves

Lofting creates a smooth surface that blends between selected curves. The curves define "ribs" for the surface you are creating.

Create a lofted surface

  1. Open the tutorial model Loft.3dm.

    (Help menu > Learn Rhino > Tutorials and Samples > User's Guide > Loft)

  2. On the Surface menu, click Loft.

    Optional: Press F1 to review the Help topic for the Loft command.

  3. At the Select curves to loft prompt, select the three curves (1), (2), and (3) as shown in the illustration below, and press Enter.

    Tip: Select the curves by picking near the same end where the numbers are. This avoids twisting the loft surface. In this model, you can use any selection method. The Loft command will sort out the order of the curves. In other more complex cases, picking the curves near the same end may be important, and you may have to make adjustments for the loft to work properly.
  4. in the Loft dialog box, click the drop-down menu under Style to try some of the options.
    The default style is Normal. As you change the style, the preview will update in real time to show you what the results will be.

  5. In the Loft Options dialog box, click OK.

Revolve curves

Revolving creates a surface by revolving curves about a revolve axis. The curve defines the silhouette of the revolved surface. This action is sometimes called lathing in other programs.

Create a revolved surface

  1. Open the tutorial model Revolve.3dm.

    (Help menu > Learn Rhino > Tutorials and Samples > User's Guide > Revolve)

  2. In the Status bar, click the Osnap pane to turn on the Osnap control.

  3. In the Osnap control, click End.

  4. On the Surface menu, click Revolve.

    Optional: Press F1 to review the Help topic for the Revolve command.

  5. At the Select curves to revolve prompt, select the curve (1) and press Enter.

  6. At the Start of revolve axis prompt, snap to one end of the line (2) that defines the revolve axis.

    Note: A reference line is not strictly necessary; you can pick any two points to define the axis.

  7. At the End of revolve axis prompt, snap to the other end of the line (3) that defines the revolve axis.

  8. At the Start angle... prompt, click the FullCircle option.

    The FullCircle option creates a complete 360-degree surface.

Revolve curves with a rail

Rail revolve creates a surface by revolving a profile curve around a reference axis while at the same time following a rail curve as closely as possible. The profile curve defines the silhouette of the surface, and the rail curve defines a path the profile curve will try to follow.

Create a revolved surface with a rail curve

  1. Open the tutorial model RailRevolve.3dm.

    (Help menu > Learn Rhino > Tutorials and Samples > User's Guide > RailRevolve)

  2. On the Surface menu, click Rail Revolve.

    Optional: Press F1 to review the Help topic for the RailRevolve command.

  3. At the Select profile curve prompt, select the profile curve (1).
  4. At the Select rail curve... prompt, select the rail curve the revolve will follow (2).
  5. At the Start of RailRevolve axis prompt, snap to an endpoint of the axis line (3).
  6. At the End of RailRevolve axis prompt, snap to the other end of the axis line (4).

Sweep along one rail curve

Sweeping with one rail creates a smooth surface with from multiple cross-section curves and a single rail curve. The cross-section curves define the surface shape, and the rail curve defines a path the surface will follow.

Create a sweep surface with one rail

  1. Open the tutorial model Sweep1.3dm.

    (Help menu > Learn Rhino > Tutorials and Samples > User's Guide > Sweep1)

  2. On the Surface menu, click Sweep 1 Rail.

    Optional: Press F1 to review the Help topic for the Sweep1 command.

  3. At the Select rail prompt, select the rail curve (1).
  4. At the Select cross section curves... prompt, select the cross-section curve (2), and press Enter.
    Only one cross-section curve is used in this example.
  5. At the Drag seam point to adjust... prompt, press Enter.
    No adjustment is necessary in this case.

  6. In the Sweep 1 Rail Options dialog box, click OK.

    The default Freeform option will be used.

Sweep along two rail curves

Sweeping with two rails creates a smooth surface with from multiple cross-section curves and two rail curves. The cross-section curves define the surface shape, and the rail curves define the path the two edges of the surface will follow as closely as possible. Use the Sweep2 command when you want to control the location of the edges of the surface; for example, when the using the edges of other surfaces as the rail curves.

Create a sweep surface with two rail curves

  1. Open the tutorial model Sweep2.3dm.

    (Help menu > Learn Rhino > Tutorials and Samples > User's Guide > Sweep2)

  2. On the Surface menu, click Sweep 2 Rails.

    Optional: Press F1 to review the Help topic for the Sweep2 command.

  3. At the Select first rail... prompt, select the first rail curve (1).
  4. At the Select second rail... prompt, select the second rail curve (2).
  5. At the Select cross section curves prompt, select the two cross-section curves (3) and (4), and press Enter.

  6. In the Sweep 2 Rails Options dialog box, click OK.

    No further adjustments are needed in this case.

 

 

Rhino for Windows © 2010-2018 Robert McNeel & Associates. 24-Nov-2021

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