Homogeneous Filtering

 

Filtering a cloud of points makes its manipulation easier.
This task shows how to filter a cloud of points homogeneously.
When you select Homogeneous, a sphere appears.
You can change its radius via the Homogeneous counter in the dialog box.
This modifies the sphere dimension on the screen and the filtering percentage:
  • The sphere passes over the cloud of points, starting on the first point met.
  • All the points that are inside the sphere are then hidden.
  • The sphere goes to the next remaining point and removes the points that it contains, and so on. 

See the Protect command to protect characteristic lines.
  • The points are hidden, not removed, unless you select the Physical removal check box.
  • Within a filtering action, Undo cancels the last filter action performed.
  • Leaving the action with Close restores the cloud as it was before starting the filtering action.
  • It is not possible to filter a meshed cloud of points.
  • When you filter scans or grids, you actually filter points: filtered points are hidden, and new scans or grids are created.
  • Points that have been physically removed can not be retrieved.
  • To avoid memory problems, do not type too low a radius value.
  • The sphere radius should not be smaller than the digitizing step.
Open the Cloud1.CATPart model the from the samples directory.

 

  1. Click Filter in the Cloud Edition toolbar and select the cloud of points. 

  2. The Filter dialog box appears.

  3. Select Homogeneous. A sphere is visualized by a green sphere.
    You can change its position by a simple mouse click.
    The sphere radius value is displayed in the current unit.
    You can type the value in another unit, but it will be recomputed and displayed in the current unit.

  4. Each time you click Apply, the computation is restarted on the whole cloud of points.
    The display of the cloud of points and the statistics are updated. 
    Step: 0 Points to be filtered: 14335 Remaining points: 14335 (100.00%)

    Step: 1 Homogeneous Radius: 4.78 Remaining points: 986 (6.88%)

    Step: 2 Homogeneous Radius: 9.56 Remaining points: 284 (1.98%)

  5. Select the Physical removal check box to delete the filtered points, thus optimizing the memory requirements.

  6. Click Reset to retrieve all the filtered points, i.e. points hidden in the present filtering action or in previous filtering actions, provided you did not select the Physical removal check box.

  7. Once you are satisfied with the result, click OK to confirm and exit the action.