Automatic Forced Sweepability

In some cases, a volume can be "forced" into a sweepable configuration by compositing surfaces on the linking surfaces. The automatic forced sweep command will attempt to automatically composite linking surfaces together to create a sweepable topology. This command can be useful in cases where there are many linking surfaces that prohibit sweepability and are not needed to define the mesh. It is assumed that the user has assigned the source and target surfaces for the sweep prior to calling this function. Trelis will try to composite linking surfaces together to get rid of problems such as 1) non-submappable linking surfaces, 2) interior angles between curves of a surface that deviate far from multiples of 90 degrees, and 3) surfaces with curves smaller than the small curve size, if a small curve size is specified. This command is incorporated into the ITEM GUI, but is also available from the command line using the following command syntax.

To use automatic forced sweepability

  1. On the Command Panel, click on Geometry and then Volume.
  2. Click on the Modify action button.
  3. Select Auto Clean from the drop-down menu.
  4. Enter in the appropriate values for Volume ID(s). This can also be done using the Pick Widget function.
  5. Enter in the appropriate value for Small Feature Threshold Size.
  6. Click Force Sweepability from the Select Auto Clean Method menu.
  7. Click Apply.

Auto_clean Volume <id_range> Force_sweepability [Small_curve_size <val>]

The small_curve_size qualifier is an optional argument. If a curve size is specified, the command will try to remove surfaces with curves smaller than this size by compositing the surface with adjacent surfaces.


The following cylinder has been webcut and had surface splits so that it is not sweepable. The split surface command has also introduced 3 small curves on the surfaces. After the source and target surfaces are set, the force sweepability command is issued to automatically composite neighboring surfaces to make the volume sweepable and remove the small curves. The results are shown in the image below.

auto_clean volume 1 force_sweepability small_curve_size .7

Figure 1. Linking surfaces are composited to force a sweepable volume topology