Find and fix noise

Noise can be easily identified in a Graph view:

It also produces flickering as you play through a take in the 3D Scene view. You can fix it with the filtering options in the Marker Editing panel.

To fix noisy data:

In a Graph view, ALT+drag to select it.
At the bottom of the Marker Editing panel, expand the Filter section, and select whether filtering applies to Ranges, as above, or to Selected Keys.
If you're not sure how much filtering to apply to your data, keep the default settings (Cut Off: 0.3 and Threshold: 15) and select Apply. You can reapply this as many times as required.
In the Graph view and 3D Scene view, check that the trajectory is now smooth over the selected range.
Tip: To display a tooltip for any of the controls, hover the mouse pointer over the relevant control.

Ensure smooth start and end to filtered trajectories

When you apply filtering, the Smooth In/Out option in the Marker Editing panel provides smooth blending at the start and end of the filtered section of a trajectory curve.

The following example shows a Graph view of a trajectory curve that requires smoothing.

With Smooth In/Out cleared, when filtering is applied, the curve is made smoother, but the start and end does not take into account what is on either side of the smoothed section, resulting in a straight line, with an unwanted angle at the end.

For details, see the following steps or watch Vicon Shogun 1.3 Post Tutorial - Filter in/out Smoothing on YouTube.

To give a smoother start and end to the filtered section of a trajectory:

In the Marker Editing panel, expand the Filter section and ensure Smooth In/Out is selected.
If you want to change how much of the trajectory is affected on either side of the gap, edit the value of the adjacent field. The default is 0.2 (20%). Smoothing works by blending between the original and filtered result by progressively more or less, across the smoothing range.
The filtered section is smoothed at the start and end.