To create a set of curves using edit point curves

1. Set the Z-scans layer to Visible and Set state > Pickable.
2. Isolate one scan line that encompasses the model.
3. Hide the unselected scan lines. (Use the ObjectDisplay > Hide Unselected menu item).

   

4. Create a degree 2 edit point curve at the middle portion of the scan line by snapping the endpoints to the scan line. (Use the Curves > New Curves > New Edit Point Curve tool).

   

5. Pick the middle CVs and move the CVs in the Y-direction until you fit the shape of the scan line.

With flat shapes, you may find it difficult to judge the shape of your curve. To get a better view of your work, go to the Viewing Panel by pressing + (Windows) or + (Mac). Inside the Viewing Panel, examine the four icons in the bottom rectangle. Make sure that the box beside the Perspective option does not contain a check mark. Inside the bottom rectangle, choose the square icon. You will now be able to dolly your view in a non-proportional manner that should provide for a better view of how your curve fits to the scan line.

To use the icons in the Viewing Panel

1. Press + (Windows) or + (Mac) and hold down the buttons.
2. Make sure that the Perspective option does not contain a check mark.
3. Choose the square icon. The icon will turn white to show that it is engaged.
4. Keep holding down the + (Windows) or + (Mac) keys. (The Viewing Panel must remain open to execute the view change).
5. Use the mouse buttons to scale the view.
   NoteThe scales the view both horizontally and vertically, the operates on the horizontal scale, and the is reserved for the vertical scale.
6. To return to the original view, choose the Perspective option and then remove the check mark. The view should return to the natural scale in the orthographic view.
7. If the non-proportional view is not sufficient, choose the circled arrow icon at the bottom of the Viewing Panel to spin the view. To return to the original view, use the black arrows that surround the car icons in the middle of the Viewing Panel.
8. To fashion the front/rear curve, use the same technique employed on the X-scans.

Tips for creating a set of curves using edit point curves

• Use the Curve Edit > Fit Curve tool.

  

• Mirror the fitted curves.

  

• Create two degree 5 edit point curves.

  

• Shape the degree 5 curves to fit the scan line. Remember to move corresponding CVs to maintain the curve’s symmetry. As well, when moving CVs in the Y-direction, use the non-proportional scale and center the pivot.

  

When creating the transition between the front portion of the curve and the middle portion of the curve, use a degree 5 edit point curve to bridge the endpoints.

After completing work on the Z-scan line, the degree 5 edit point curve looks similar to the curve used in blending the center line. Note that the current straight line is not a blend curve. Instead, it is a degree 5 edit point curve that allows for the use of Object Edit > Align > Align 2008

To use the Align tool for aligning two curves

1. Choose the Z-scan layer option Set state > Reference.
2. Double-click the Object Edit > Align > Align 2008 tool icon to produce the option box.
3. Select the edit point curve at the marked point (blue arrow) to align the curve beginning with the selected end.
4. Select the top reference curve at the marked point (red arrow) to align the first picked curve to the second picked reference.

   

5. Set the Object Edit > Align > Align 2008 tool options as shown above.

   By setting the Continuity option to TANGENT, you will notice that just the first and the second CVs are highlighted in yellow. If you change the Continuity to CURVATURE you will notice that the third CV is highlighted as well.

6. Repeat Steps 3-5 for the other side.

The Continuity level determines how many CVs are highlighted, or influenced. This knowledge is crucial to understanding the alignment of surfaces later in the tutorial.

The basic concepts behind the primary Continuity settings

1. POSITION means the first CV will be moved to the reference.
2. TANGENT means the first and the second CVs have to be moved to achieve the quality.
3. CURVATURE means that, in addition to the first and second CVs, the third CV will also have to be moved to achieve the quality.

Now, it should be clear that in order to achieve curvature continuity on both sides of the curve, a minimum number of 6 CVs is required. Use a degree 5 single span edit point curve to achieve these results.

To direct model a curve

To fit the curve to the scan line you can now use the SLIDE option in the CV Move shelf located at the bottom of the Control Panel. After sliding a CV, the Object Edit > Align > Align 2008 tool will always bring the CV back into alignment. By proceeding in controlled steps, you will achieve a proper deviation.

Also, don’t forget the possibility of changing the start points of the reference curves. Click the first CV of the reference curve and move the CV while pressing + (Windows) or + (Mac) (curve snap) along the scan line.

Three additional curves will have to be fitted to the Z-scan lines. The new curves will serve as guides for developing the front end surface and the transition surface. Use the methods previously described in this section to fit the Z-scan lines.

Your completed curves should resemble the image below - the spheres mark the endpoints of the curves.

To clean-up your work

1. Create a new layer and name it “Z CRV”.
2. Assign the curves to the layer.
3. Make the scan line layers invisible.
4. Make all new curve layers visible.
5. Save your work.