Insert Surface Lofted Automatic


 

The Lofted Surface command enables you to create "lofted" surfaces which are best suited to the input parameters. That is to say that, once you have selected the input parameters, the program will automatically create the best suited surface among the following set of types: Ruled, Proportional, Stretched, Connect, Grid.

There are two main selection modes, to be selected in the Select As drop-down list:

Grid enabling you to select up to two orthogonal sets of parallel curves (Boundary Set A and Boundary Set B), thus allowing the automatic creation of the following types of surfaces:
  • Ruled — when two boundaries are selected in Boundary Set A and none in Boundary Set B
  • Proportional — when up to two curves are selected in Boundary Set A (the drives) and up to two curves are selected in Boundary Set B (the boundaries).
  • Proportional or Stretched — when two curves are selected in Boundary Set A and two curves are selected in Boundary Set B. Clicking the Next item in the selection list you can switch from one type to the other.
  • Grid (UV Curve - U Curve) — when two or more "parallel" curves are selected in Boundary Set A and none, one, two or more "parallel" curves are selected in Boundary Set B
    • If the first or the last curve selected is the border of an existing surface, the Continuity drop-down list will be displayed, so as to enable you to select positional or tangency continuity. If you select the latter and if each curve intersecting the selected surface border is in the tangent plane of the surface border at the point of intersection, the resulting surface will have tangency continuity with the existing one along the selected border.
    • It is possible to manage the selection of closed curves both in Boundary Set A and in Boundary Set B.
    • Finally, it is possible to manage the extension of the resulting surface in both orthogonal directions with no need to spend time providing any additional curve.

Optionally, you can create a connection surface, like the ones you obtain using the Connect Surface command.
Cycle enabling you to select a closed loop of Boundaries, thus allowing the automatic creation of Stretched surfaces.

The Type drop-down list under More Options enables you to prevent the program to automatically decide which type of surface to create and to specify exactly the surface type you want among the said ones.

A set of Quality Checks is also available, enabling you to study the shape of the resulting surface.

Associativity
The surfaces created using this command can be associative: associative surfaces are Skins, that is open solids, retaining a link to the base curves, so that if you modify the base curves the surfaces will be modified accordingly; they have a history and are displayed in the Model Structure. See " Associative Surfaces (Skins)" for details.

Cleaning curves before creating a Lofted surface and choosing the Parameterization
There can be cases where the curves selected to define a surface have non-visible sharp points. These points will be identified during the surface construction process. Using these curves directly as they are can result in a surface with strange artifacts such as creases or folds. By choosing the Clean curves or Curvilinear options in the Parameterization drop-down list under More Options - Surface Type Options, these artifacts can be greatly reduced. The original curves are not affected and the original shape is preserved by this process.
Three options are available in the Parameterization drop-down list:
  • Intrinsic
    The ordinary curve parameterization. Though this type of parameterization can be used in most of the ordinary situations, you might need to use another one in order to get a smoother surface. For example, sharp points, if any, are not detected when using the intrinsic parameterization.
  • Clean curves
    When some of the curves to be used in the creation of a lofted surface have invisible sharp points, the quality of the resulting surface might be lower than expected. As soon as a curve containing an invisible sharp point is selected, an appropriate message is displayed. By selecting this item, you can create a nicer surface. The command will not use the original curve, which will not be changed, but a local copy with no sharp points (thanks to a different parameterization).
  • Curvilinear
    A normalized arc length parameterization type (which is: the curve parameter varies proportionally to the curve arc length, so that arcs with equal length on the curve correspond to equal variations of the curve parameter).
    Using this option all the input curves are internally re-parameterized based on their arc length and you will generally get surfaces with more regular isoparametric curves.
    Please note that if the selected curves have invisible sharp points, using this option will also result in creating nicer surfaces as in the case of the Clean curves option.

See Cleaning a curve before creating a lofted surface for details.

The Restore Selection button ( ) — enabling you to use the last selections and settings again without having to repeat them all — is also available. See " Restore Selection modality for selections and settings" for details.

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