InsertPointExtract Zones

The Extract Zones command enables you to extract zones on Mesh (or couple of Meshes) based on the specified criteria and then create associated set of points. Primarily the command processes point data which is sourced from the Mesh nodes of a selected mesh. However, you can also use ASCII file (point cloud data), or Standalone points.

The Extract Zones command has diverse application and hence is available both with Compensator and HQ Reverse Engineering.

• In the context of Compensator it extracts zones from the two meshes simultaneously in a homogeneous way (since the two meshes will be used to define a displacement field and from & to points).
• In the context of HQ Reverse Engineering it is used for extracting zones from a single Mesh (that has been analyzed by the Mesh Analyzer command, and would be an input for the Super Capping command).

For the cases where you make two sets of input, the extraction criteria is evaluated on the Leading Points (hence is always mandatory), and the extraction is performed in a homogeneous way on the Leaded Points (optional) to preserve a valid displacement field definition.

The various criteria for zone extraction can be selected from the Mode drop-down list.

• Noise: used to estimate noise on the mesh.
  
  
• Small curvature radius: used to estimate the minimum curvature radius of the mesh
  
  
• Curvature variation: used to estimate the variation of the computed curvature on one point with the curvature computed on its neighboring points. This criterion tends to be zero on all points in a zone with the same curvature.
  
  
• Curvature difference %: used to estimate the percentage of curvature difference between one point on the leading mesh and its corresponding one on the leaded mesh. This criterion tends to be zero in zones that have same curvatures in both meshes. Note that for this criterion, it is mandatory to provide both First Points and Second Points inputs.
  
  
• Free boundary: used to check the free boundaries on the mesh.
  
  

If the input point data is coming from existing support surfaces, you can optionally select these surfaces for Leading Surfaces (or for First surfaces and Second surfaces in case of Curvature difference %) and to act as reference so that the curvatures are evaluated more precisely (on these surface).

The Max. presumed distance check box can then be selected to speed up the finding of corresponding points on these surfaces.

Irrespective of the selected criteria, you can force the computation to include or exclude the points on the free boundaries. Select Include free boundary nodes check box to include nodes on free boundaries even if some of them don't match the criteria. Select the Exclude Free Boundary Nodes check box to exclude nodes on free boundaries even if some of them match the criteria. Note that you can only select either of the check boxes at a time.

You can optionally decide to include only those free boundaries of holes which enclose an area greater than the specified threshold. To do so, select the Ignore Holes with Small Area check box and specify the threshold value in the corresponding text box.

After making the required selections and settings, select the Preview button to perform the analysis. The key values of the analysis result are displayed in the selection list. Also, the distribution of the result can be viewed graphically by selecting the Graph option. In case of Mesh, you would also see a color map over it. You can choose the required threshold value to be used on the given criteria to create the associated set of points.