Guided loft: Create a surface using Variation options

Description: 5 minutes; Lab exercise: 20 minutes

Choose from three variation options to modify your guided loft surface.

For non-planar or non-orthogonal profiles where the attachment point position is not clearly defined, the result may be unexpected.

Lab exercises

Create a surface with scalar variation

  1. Save the file variationOptionsScaling.pkg on your system.
  2. Load the variationOptionsScaling.pkg file.
  3. Click Surfacing .
  4. Click Guided Loft in the Create Face section.
  5. Select the line as the Spine.
  6. Select the box as the Profile Edges.
  7. Click Preview.
  8. Expand Variation Options and choose an option from the Scalar drop-down menu.
  9. As you change options in the Scalar menu, type values and weights into the dialog to see what happens to the surface with each situation. The larger the weight, the longer the scale value is kept before the other value is used for sweeping the profile along the spine.
  10. Click to complete the operation.

Scalar: Three Values with Start and Mid at 1, End at 2, Start Weight and End Weight at 1, Mid Par at 0.7.

Create a surface with angular variation

  1. Save the file variationOptionsTurning.pkg on your system.
  2. Load the variationOptionsTurning.pkg file.
  3. Click Surfacing .
  4. Click Guided Loft in the Create Face section.
  5. Select the line as the Spine.
  6. Select the box as the Profile Edges.
  7. Click Preview.
  8. Expand Variation Options and choose an option from the Angular drop-down menu.
  9. As you change options in the Angular menu, type angle values and weights into the dialog to see what happens to the surface with each situation. The larger the weight, the longer the scale value is kept before the other value is used for sweeping the profile along the spine.
  10. Click to complete the operation.

Angular: Three Values with Start and End at 0, Mid at 90.

Create a surface with offset scaling

  1. Load the reduced.pkg file.
  2. Click Surfacing .
  3. Click Guided Loft in the Create Face section.
  4. Select the long curve as the Spine.
  5. Select the smaller curves on either side of the spine as the Profile Edges.
  6. Click Preview.
  7. Expand Variation Options and choose an option from the Offset drop-down menu.
  8. Type a value in Offset. The offset is a length value applied to the profile. The value can be positive, negative, or zero.

For a specific point on the profile, the offset direction lies in the profile plane and is measured from the point toward the face normal (shiny side) of the surface. A negative offset or a negative scaling leads to an offset to the -face normal (dull side).

  1. Modify the offset value with a scaling function that will modulate the offset value along the spine. Select an option from Scale along Spine.  These options are the same as those in scalar variation.  As you change options in Scale along Spine, type values and weights into the dialog to see what happens to the surface with each situation. The larger the weight, the longer the scale value is kept before the other value is used for sweeping the profile along the spine.

Use Reverse to switch the start and end points of the 2D curve.

  1. Click to complete the operation.

   

Offset: Offset: 0.2 inches; Scale Along Spine: 2D Curve

2D Curve

The distance in the direction of the V axis is interpreted as the "value" of the function at the U position (a relative position on the spine between the start and end of the spine).

The Origin is shown by the construction point. The 2D curve has a start position at the first construction line and an end position at the second construction line. The vertical line shows the distance - in the V direction - between the U position of the spine and the origin.

 

A 2D curve that contains two V values (on the vertical line) for one U value (relative position on the spine) cannot be used as a function. If a vertical line (parallel to the V axis) intersects the curve more than once, the curve cannot be used for scaling.

The Origin is shown by the construction point.  The V direction intersects the 2D curve twice.  

 

The 2D curve cannot be negative, or smaller than the V value of the origin because the distance would be negative and the surface would be self-intersecting.

The Origin is shown by the construction point.  The 2D curve and the function become negative with respect to the V value of the Origin.