Filtering a Cloud

You can filter a cloud of points, either with the Adaptative method or with the Homogeneous method.

This task shows you how to:

Before you begin:
  • It is impossible to filter a meshed cloud of points.
  • When you filter discrete polyline or grids, you actually filter points: filtered points are hidden and new discrete polylines or grids are created.
  • While filtering, undo cancels the last filter action.
  • Close restores the cloud as it was before starting the filtering action.
Tip: When you create a mesh from a filtered cloud of points, specify the Neighborhood value (if used) at at least 3 times the value of Homogenerous or Distance (depending on the Filter Type).

Filter a Cloud with the Homogeneous Option

You can use the Homogeneous method to hide points equally everywhere on the cloud of points.

  • A sphere passes over the cloud of points, starting on the first point met.
  • All the points that are inside this sphere are then hidden.
  • The sphere goes to the next remaining point and removes the points that it contains, and so on.

  1. Optional: Activate Undo/Redo for in-place cloud edition commands in General.
  2. From the Prepare section of the action bar, click Filter Point Cloud and select the cloud of points.
  3. Select Homogeneous.
    A sphere is displayed.
    Notes:
    • You can change its position by a simple mouse click.
    • The sphere radius value is displayed in the current unit.
    • You can enter the value in another unit, but it is computed again and displayed in the current unit.
  4. Click Apply.

    Note: 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.

  5. Optional: By default, Filter hides the points.
    1. To delete them, thus optimizing the memory requirements, select Physical removal.

      Important: Points that have been physically removed cannot be retrieved.

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

Filter a Cloud with the Adaptive Option

You can use the Adaptative method to hide more points from the planar areas than from other areas, enabling you to highlight bent areas.

  1. Optional: Activate Undo/Redo for in-place cloud edition commands in General.
  2. From the Prepare section of the action bar, click Filter Point Cloud and select the cloud of points.
    The Filter dialog box appears.
  3. Select Adaptative.

    The value to type represents the local chordal deviation.

  4. Click Apply.

    Note: 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.

  5. The free boundaries have not been respected. To preserve the shape of the part, and to avoid the creation of too heterogeneous a cloud of points, specify a threshold for filtering: Select the Distance check box and key in a value.
    Except for points that respect the chordal deviation, the distance between two remaining points in near-planar areas is at least equal to this value. The Distance is represented by a sphere.
  6. Optional: By default, filtered points are hidden.
    1. To delete them, thus optimizing the memory requirements, select Physical removal.

      Important: Points that have been physically removed cannot be retrieved.

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