Use this command to create a trimmed face that passes through a set of points or a point block referred to as a point cloud. With this approach you can divide up an overly complex set of point data into separate sections.  Instead of one very large surface, several smaller, tangentially connected patches may be generated. Each patch can be based on a portion of the input point data for which a common projection direction does not exist.

 

This should both speed up the overall process and also enable the processing of "360" degree scan data.  The only required inputs are the input points the face must pass through and the set of boundary curves used to trim the face.  This command can be used on imported STL data.  Refer to the Optional Inputs section below.

 

 

 

Use this command to create an untrimmed face that passes through a set of points referred to as a point cloud. The only required input are the points the face must pass through.

 

The optional inputs are numerous. They include defining the U direction, the total number of control points for the face, the U/V ratio and additional FEM settings such as spring constant and bending resistance. You can also modify an existing face to pass through the point cloud.  Refer to the Optional Inputs section below.

 

 

 

Use this command to create an untrimmed face that passes through a set of points (referred to as a point cloud) read from a point file. The point file should be in ASCII format and adhere to the structure described below.

 

The only required input is the point file. The optional inputs are numerous. They include defining the U direction, the total number of control points for the face, the U/V ratio and additional FEM settings such as spring constant and bending resistance. You can also modify an existing face to pass through the point cloud.

 

 

Point File Format

 

<group_label> and the Z coordinate are optional. When you enter a group label, only points from that group are imported. The file may contain comments preceded by a pound sign (#).

 

#comment   <group label> x,y,z x,y,z    .    .    .   <group label> x,y,z x,y,z    .    .    .

 

 

  Notes

 

• If you have a point file, using this command to create the face will be much faster than using the Import Points from File command and then using the Fit Face to Points command. The selection and sorting of the points after they are imported will slow the process down. The point file is imported based on the default part units. Use the Part Settings Form to modify the part units if desired before importing the point file.
   

• VX stores the contents of the point file with the point cloud feature. The stored data is updated every time the part is regenerated. If the file is lost or corrupted, a record of the last data that was read from the file is always available for regenerating the part.
   

 

 

Delimiter

Specify the delimiter format of the imported point cloud file.  Comma and Space are currently supported.

 

Face

Select an untrimmed base face to modify or middle-click to create a new face.  If a face is selected, edges are handled automatically such that the tangency is largely maintained across a seam. The continuity across a seam edge depends on the point data near the edge.

 

FEM Settings

Spring Constant, Bending Resistance

These commands create surfaces based on energy minimization.  Use the slider bars to set the spring constant and bending resistance values.  See Finite Element Methods (FEM) for Surface Creation for more information.

 

Label

Define a label for the feature if desired.

 

Normal - Use this to define the base face direction.  This allows you to re-orient the overall direction of the fitted shape, in case the built-in method does not detect it properly or you wish to use a different direction as a preference. Occasionally, less than ideal scan data can cause such ambiguities.

 

Num point

This option sets the total number of control points for the resulting face. The lower limit and the default value (with no other input) is100. Entering a lower value will be changed to 100. If a less defined face is desired, use the FEM Settings below to make additional adjustments.

 

If you select a set of sample points and then middle-click, a logarithmic scale is used to generate a value based on the total number of points selected.  For example, if 30,900 points are selected (see image above) this value will be 2,808.  This then becomes the new default value but only AFTER the point selection is made. You can accept this value or override it with another either from this Options Form or in the text input field.

 

If you edit this field first BEFORE points are selected, the value you enter will not change even after a point selection is made. This can be used to reduce or increase the number of sample points for the resulting face. Also refer to the Notes section below.

 

Optimize point data

Use this option to optimize the point data.  By default, this option is checked.  If unchecked, the resulting surface is calculated with no optimization.  While this may help improve surface detail, it will take significantly longer to calculate and also limit the amount of point data the commands can handle.  During the Untrimmed Face from Point Cloud File command (see above), this option works in conjunction with the Reduce point set option (see below) based on the specified Tolerance value (see below).

 

Reduce point set

Check this box to reduce the total number of points used from the point cloud file and enter a tolerance value (see below). The total number of points that can be reduced is unlimited.

 

Refit base face

When the Face option (see above) is used, check this box to refit the base face during the command.  This means that more control points can be added to the surface, if necessary, to better fit the point cloud data.

 

If unchecked, you can prevent the command from adding more control points before the surface is fitted through the point data. It will use existing control

points as degrees of freedom and try to fit the data.

 

This will speed up the process and will also keep the same UV surface parameter values for the sample data points throughout multiple surface fitting iterations.  This helps to prevent a "shifting" or "pinching" effect that can arises if slightly different UV parameter values are assigned during each iteration.

 

Reset

Use this option to reset the FEM Settings (see above) sliders to their system default positions.

 

Specify sample density, Density - Use this to set the sample point density.

 

• If you check this box - In the Density field, enter the average number of sampling points on the boundary curves. VX then computes the actual number of sampling points according to the relative length of each curve with regards to the total length of all curves.

 

• If you do not check this box - VX automatically uses a discretization method for sampling the points on the boundary curves.

 

Tangent at boundary - Check this box to enforce tangent continuity across the resulting surface boundary.

 

Tolerance

This command spatially sorts points and keeps only one point in each tolerance-sized region.  If the tolerance is set to zero or left blank, a guess is made at a reasonable tolerance. Fewer points mean less accuracy but greater system performance.  For lower tolerances, use the Create point block option above.

Also refer to Common Optional Inputs (see below) for options not listed here.

 

U degree, V degree - This is the degree of the resulting surface. Lowering the degree values will generally result in a simpler surface.

 

U-direction, V/U ratio

The U-direction is used in conjunction with the U/V ratio to better distribute the available control points. Once the U-direction is specified, the U/V ratio can be used to control how many points there are per row in the U and V directions. The allowed value range is 0.01-100.

 

For example, the resulting face is to be about 10 times longer in the V direction. Increasing the U/V ratio to 10 will assign more control points to the V direction. The maximum value of 100 will work for even larger ratios since most of the control points will be assigned in the V direction anyway.  Refer to the Notes section below for more information.

 

 

 

 

 

 

 

 

 

 

• The number of entities picked that is echoed in the Text Input Field may not be the actual number of points if point blocks are included in the point selection.
   

• The maximum number of control points for the given fitted surface is approximately 100,000 (9 minimum). This number allows more complex surfaces to be fitted without overly sacrificing system performance.