CROSS SECTION

Pointcloud Operator dialog box - CROSS SECTION Operator

The CROSS SECTION operation generates a subset of polylines determined by the defined intersection of a set of parallel planes with the COP or Mesh object. The set of planes is defined by the start point, direction vector, step distance between the planes, and length. The number of planes is determined by the Step distance divided into the Length plus one.

The CROSS SECTION operator can be evaluated by the profile dimension.

To apply the CROSS SECTION operation to a pointcloud, click Cross Section Pointcloud () on the Pointcloud toolbar, or select Insert | Pointcloud | Cross Section.

From the Pointcloud or QuickCloud toolbar, click the 2D Section Slide Show button to display cross sections in the 2D view. For details, see the "Cross Section Slide Show" section of the "Show and Hide Cross Section Polylines" topic.

The list underneath the Operator list contains these options: Vector, Axis, Curve, and 2 Points. For details on how the Curve function works, see the "Creating a Cross Section along a Curve" topic. For details on the 2 Points option, see the "Creating a Cross Section between 2 Points" topic.

The CROSS SECTION operator uses the following options:

If the value in the Step box is greater than the value in the Length box, then only one section cut is created at the start point.

When you use the Smoothing Factor, PC-DMIS applies a Least Square fit with a smoothing constraint to an ordered set of points. There is a trade-off when using the Smoothing Factor, since, as the roughness of the spline is smoothed, the points move from their original position. Consequently, you should use caution when you apply the smoothing factor since it moves or changes the data. This option may be useful for smoothing points that you consider to be "noise".

There is no upper limit to the Smoothing Factor value. However, the more you increase this value, the less effect it has on your data until any noticeable change is seen. When you use a very large smoothing factor, changes occur to the original shape of the measured cross section polyline.

You should test the Smoothing Factor option with a starting value between 0.1 and 0.25. Then, depending on the result, increase the value to 0.5, 1 or 2 and re-test until you achieve the desired result.

Example with the Smoothing Factor set to 0 (zero)

 

Example with the Smoothing Factor set to 0.5

Point Spacing is also defined by the CrossSectionCopCadCrossSectionStep registry entry. For details on this registry entry, see "CrossSectionCopCadCrossSectionStep" in the PC-DMIS Settings Editor documentation.

The minimum and maximum points are recalculated each time the measurement routine is executed.

For example, if you selected surface A after the start and end points are defined, only the cross sections at B and C would be generated:

Example of a selected surface (A) limiting the cross sections to only (B) and (C)

Selected surfaces do not affect what you see when you click the View button.

When the cutting planes are visible in the Graphic Display window, you can manipulate them as follows:

When a cross section is created or edited, the cutting planes appear in a transparent view as shown above.

Click Create to:

For example:

COPSECTION3=COP/OPER,Cross Section,TOLERANCE=0.05,WIDTH=117.715,HEIGHT=227.086,

START PT = -6.439,60.097,6.276,NORMAL = 0.9684394,-0.2221293,-0.1130655,SIZE=76

REF,COP1,,

The black polylines represent the nominal CAD, the yellow polylines represent the COP polyline.

Finished cross sections showing six planes

Defining the Cross Section by Typing Values

Use the Pointcloud Operator dialog box to type the values:

Defining the Cross Section by Using the Graphic Display Window

To define some of the cross-section parameters, click the CAD model in the Graphic Display window to select the Start Point. A pink line appears. Click a second point on the CAD model to determine the Direction vector and the Length.

Creating a Profile Dimension from the Graphic Display Window

When you double-click a cross section label, a new profile dimension is created that evaluates the selected cross section.

Measuring a Radius on a Cross Section with the 2D Radius Gage

PC-DMIS provides the 2D Radius Gage to quickly measure the radius on a pointcloud cross section. For details, see "2D Radius Gage Overview".

More:

Pointcloud Operators

2D View of Cross Sections

Creating a Cross Section along a Curve

Creating a Cross Section between 2 Points

Show and Hide Cross Section Polylines

Measuring Cross Section Distances

Viewing Cross Section Labels in Reports