Pick section data

How to pick section lines and section line data points.

Pick section lines

• Use Pick > Object.

Pick section data points

• Use Pick > Point types > CV.

Set up the Pick component tool to pick only section lines

1. Choose Pick > Component p.
2. Turn off all the pickable types except Sections, then click Go.
   TipOnce you have set the options, you can drag the tool onto a shelf to have a custom tool that only picks section lines.

Sort section lines into layers

Sorts section lines into layers based on their axis orientation.

Sort section lines

1. Pick the section data.
2. Choose Curve Edit > Sort sections.

   If they do not already exist, the tool creates X_sections, Y_sections, Z_sections, and Other_sections layers.

   NoteSection lines are a type of degree 1 NURBS produced from scan data in Spider and some CAD packages.

Change the display of section data

How to show or hide scan data, change the symbol used to represent section line data points, or change the section line draw style.

Show or hide all section data

1. Choose ObjectDisplay > Draw style p.
2. Open the SectionData section and set the Show Lines option.

Change the data point symbol on section lines

1. Choose ObjectDisplay > Draw style p.
2. Open the SectionData section and click one of the Point Icon symbols.

Change the draw style of section lines

1. Choose ObjectDisplay > Draw style p.
2. Open the SectionData section and set the Line Style option to either DASHED or SOLID.

Fit a curve to a section line

How to create a high-quality NURBS curve from scan data.

Section data in reference layers can be selected from within this tool.

Fit a NURBS curve to a scan line

1. Choose Curve Edit > Fit curve.
2. Click the scan line (section data).
3. Do any of the following:
   • Drag the start and end point handles to control which part of the scan line the curve is fit to. Usually you will want to fit curves to sections with little curvature.
   • Turn on the Curvature option to show a curvature comb plot on the new curve.
   • Turn on the Deviation option to show a deviation comb plot between the new curve and the scan line.
   • Edit the settings in the Fit Curve control window to try to achieve a better fit.
     TipThe new NURBS curve has construction history.

How do I achieve a better fit?

These tips are highly dependent on the shape of the curve. You may have to adjust the options and observe their effects on the curve and the deviation comb plot to see if they can help:

• Switch between Least Squares and Hull Fit settings of the Fitting Method option to see which gives you a better fit for this curve.
• Try adjusting the Stiffness and Elasticity options. Changing these values can decrease or increase the deviation.

These tips will make the curve fit the scan line better, but will also give you a more complex curve:

• Increase Degree option.
• Increase Max Spans option.

How do I get a higher quality curve?

• Increase the Curvature Constancy option. This option enforces smoother curvature on the new curve at the cost of a less accurate fit.

Fit a surface to scan data

Use the Surface Edit > Fit scan tool to automatically reshape an existing surface to match scan data.

Fit a surface to section or polygonal data

1. Create a surface on top of the scan data.

   For example, use the Square tool to snap the corners of a surface to the corners of the scan data. Usually you will want to limit the surface to an area with little change in curvature.

2. Pick the surface and all the scan data you want to fit it to.
3. Choose Surface Edit > Fit scan p.

   The tool fits the surface to the scan data.

4. Use the controls in the Fit Scan Settings window to show the deviation between the surface and the scan data, and adjust the degree of the surface and the number of spans in the surface for a better fit.
   NoteTrimmed surfaces are also supported.

Edit point clouds

How to pick, divide, subset, or merge point clouds.

Pick only point clouds

• Choose Pick > Object types > Cloud.

Separate points out into a new cloud

1. Pick the cloud you want to divide.
2. Choose Point Clouds > Subset p.
3. Under Keep which region, choose Both, then click Go.
4. Pick the points you want to separate, then click Go.

Delete points from a cloud (take a subset)

1. Pick the cloud you want to divide.
2. Choose Point Clouds > Subset p.
3. Under Keep which region, choose whether you will pick the points you want to keep (Points inside region) or the points you want to discard (Points outside region), then click Go.
4. Pick the points, then click Go.

Merge point clouds

1. Pick the clouds.
2. Choose Point Clouds > Merge.
3. Click Go.

Project a curve onto a point cloud

Use the Project curve tool to project a curve along a reference vector onto a point cloud.

Project a curve onto a point cloud

Create or edit a reference vector

1. Pick the cloud.
2. Choose Point Clouds > Project curve.
3. Click the reference vector for the projection direction.
   TipIf you don’t click a reference vector, the tool will use the sight line of the current window.
4. Click the curve to project.
5. Do any of the following:
   • Adjust the curve’s fit to the cloud by typing a new fit tolerance.
   • Click another curve to project onto the same point cloud.

What if...?

I want a better fit between the projected curve and the point cloud?

• Increase the Maximum Iterations option.
• Set the Point Location Method option to Surface Intersection.

These options are slower but can result in a better fit.

Build a surface on a point cloud

Build new surfaces using point cloud data as a reference.

Fit a surface to a cloud from four boundary curves

1. Create four curves that will be the boundaries of the new surface. These boundary curves must intersect.

   Make curves intersect

   You can also create additional curves that will be used as internal isoparametric curves for the new surface.

   TipYou can use Point Clouds > Project curve to create curves that fit to the point cloud.
2. Pick the cloud.
3. Choose Point Clouds > Surfaces > Gridded.
4. Click the four boundary curves (in any order), then click Go.
5. Click any curves you want to use as isoparametric curves on the new surface, then click Go.

   A red grid appears when you press a mouse button, showing the sampling grid. The tool samples the point cloud at the vertices of the grid and uses the sampled points to create the surface. The default grid is 15 by 15.

6. Do any of the following:
   • Drag the to set both the U and V sampling density at the same time.
   • Drag the to set the U sampling density.
   • Drag the to set the V sampling density.
   • Type two numbers to set the number of spans in U and V. The default is 2,2.
7. Click Go.

Fit a surface to a cloud from four corner points

1. Pick the cloud.
2. Choose Point Clouds > Surfaces > Corners.
3. Click four points in the point cloud to use as the corners of the new surface.

Fit a trimmed surface to a cloud from multiple boundary curves

1. Create three or more curves that will be the boundaries of the new surface. These boundary curves must intersect.

   Make curves intersect

   TipYou can use Point Clouds > Project curve to create curves that fit to the point cloud.
2. Pick the cloud.
3. Choose Point Clouds > Surfaces > Detailed.
4. Click the boundary curves, then click Go.

What if...?

I want to see the surface more clearly after I create it?

Choose WindowDisplay > Toggles > Clouds to hide point clouds.