User Guide
User Guide
User Guide

Construct Surface by Section or Network

Use it!

(3D only) Used to construct a B-spline surface that is transformed between section elements, or elements of a network.

All section elements must be in the same direction to avoid the resulting surface from being “twisted”. Before using Construct Surface by Section or Network, use the Change Element Direction tool in the Modify Curves tool box to change the sections' directions and start points so they are in a similar position to each other. As a final check, visual aids display each element's direction as it is selected.

Tool SettingEffect
Define By

Sets how the surface is constructed.

  • Section
    • — Transformed between sections (lines, line strings, arcs, ellipses, complex chains, complex shapes, or B-spline curves). The order in the u-direction is 4. The order in the v-direction is determined by the sections.
  • Network
    • — A Gordon surface is constructed, interpolating a network of elements. Each element in the network's u-direction must intersect all elements in its v-direction, and vice-versa.
Apply Smoothing

(Define By set to Section only)

If off, the continuities of the constructed surface are those of the input cross-sections.

If on, each input cross-section is approximated by a smooth B-spline curve within the specified Tolerance value, and the surface is created from the approximation curves.

Smoothing Tolerance

(Apply Smoothing on only) Lets you change the value of the smoothing tolerance value. Smaller tolerance values cause the constructed surface to follow the construction elements more closely.

To construct a B-spline surface by cross-sections
  1. Select the Construct Surface by Section or Network tool.

  2. In the Tool Settings window, set Define By to Section.

  3. Identify the sections in the order that the transformation is to follow. (You can Reset to reject a section.)

  4. Accept to display the B-spline surface.

  5. Accept the B-spline surface.

    Top Left: Identify the section elements (1,2,3, and 4). Arrows display to verify the element direction.

    Top Right: Accept to display the B-spline surface (5) and accept again to create the surface (6).

      

    With Apply Smoothing turned on, each section element is approximated by a B-spline curve, with the resulting surface being smoother.

      

To construct a surface that interpolates a network of elements
  1. Select the Construct Surface by Section or Network tool.

  2. In the Tool Settings window, set Define By to Network.

  3. Identify the first curve in the u-direction.

  4. In order, identify the other curves in the u-direction.

  5. Accept the curves in the u-direction.

  6. Identify the first curve in the v-direction.

  7. In order, identify the other curves in the v-direction.

  8. Accept the curves in the v-direction.

  9. Accept the B-spline surface.

Key-in: CONSTRUCT SURFACE CROSSSECTION

Each element (curve) in the u-direction must intersect each element (curve) in the v-direction of the network.