Clean up data

If your visual assessment and Vicon Shogun Post's diagnostic tools have revealed issues with your recorded data (see Check data quality), you can use its cleanup tools to correct mislabels and fill any gaps.

The following topics provide an introduction to fixing data issues:

See also the related Vicon videos: 5 - Shogun Post – Labeling Data and 6 - Shogun Post - Marker Editing.

Note that each time you finish cleaning up a range, you must check its solve (see Solve during cleanup).

Find and fix bad data

To help you identify and fix bad data, you can use the Marker Editing panel.

To find and remove bad data:

1. To open the Marker Editing panel, in the Processing menu, select Marker Editing (or select Marker Editing on the Processing tab of the ribbon).
2. In the Remove Bad Data section, go to the Find Bad Data button and notice the options:
   
   • Threshold Allowable deviation
   • Cut-Off Data filter. Decreasing this value filters the data more heavily.
   • Sensitivity Amplifies the effect of the Cut-Off filter.

     

3. Select Find Bad Data.
4. Experiment with these values to find out what works best for your data.
5. When you have identified the bad data, remove it by selecting the appropriate Cut button, and apply a fill (see Gap-filling options).

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:

1. In a Graph view, ALT+drag to select it.

   

2. 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.
3. 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.

   

4. 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:

1. In the Marker Editing panel, expand the Filter section and select Smooth In/Out.

2. 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.

Use the Labeling panel

You can fix labeling issues using the tools in the Labeling panel. The following steps introduce the main components of the labeling panel. To go straight to examples of how to use it to fix labeling issues, see Fix common labeling issues.

To use the Labeling panel:

1. On the Processing tab on ribbon, select Labeling.
2. In the toolbar at the top of the Shogun Post window, ensure that the required subject is selected in the Current Subject list.

   Tip: By default, the selection in the Current Subject list at the top (middle) of the Shogun Post window determines which subject to label. If All is selected in the Current Subject list, the labeler uses the last subject it was set to. If you want to select a subject different from that specified in the Current Subject list, in the Labeling panel, clear the Use Current Subject box and select the required subject from the Subject list at the left of the check box.

   On the left of the Labeling panel, a list of labels for the selected subject is displayed. The color variations indicate marker issues:
   • Yellow: Mislabels or missing labels (the depth of the color indicates the severity of the issue, eg, more or fewer gaps)
   • Red: Labels for this marker are missing from the current frame

   

3. To display a 3D representation of your labels for the current subject, click the 3D button at the top of the Labeling panel. The 3D view helps you to quickly identify where the markers should be. You can drag and drop labels from the 3D Labeling view to the 3D Scene view pane (and vice versa).

   

   You can use the usual mouse actions (click and drag, right-click and drag, left- and right-click and drag) in the 3D view, in the same way as in a 3D Scene view.
4. At the top of the Labeling panel, in the Manual Labeling Options section, select the Mode option (Select or Label), which affects the way in which you select and label markers.
   
   • Select: Select a marker on your subject in a 3D Scene view and then select a label name in the list in the Labeling panel.
   • Label: Select the name of the label in the marker list and then select the required marker on the subject in the 3D Scene view.

   Tip: To quickly switch between labeling and select modes when labeling a subject, you can use the default hot key (L) that duplicates the functionality of the Label and Select buttons at the top of the Labeling panel.

5. In the Direction line, choose to label forward (through time) or backward . You can also select both options (ie, label both forward and backward), but to help you avoid confusion, at least initially, choose either backward or forward and use only that option.

6. From the Type options, select the way in which labeling will be applied:

   

   • Whole Labels entire trajectory.
   • Fragment Labels the trajectory that intercepts the current frame.
   • Cliff Labels the current frame and continues until a specified value is encountered, which stops the labeling (see the text below in theLabeling panel, for example, the default is to skip gaps smaller than 5 frames and stop labeling at cliffs that are larger than 50 mm).
   • Ranges Lets you select an area on your graph or timeline and label only the selected time range.

In the Manual Labeling Tools section in the middle of the Labeling panel, you can correct swaps, unlabel information, and unlabel markers.

In the Semi-Automated Labelers section, you can access the Velocity Labeler, which is normally used after automated labeling, on a partially labeled take. You can use it to correct labeling where the path of a single marker consists of multiple trajectories that are consecutive in time with a small gap in between where the marker is unlabeled over part of its trajectory. The Velocity Label option is useful when a marker has been labeled for a range of time, and then becomes unlabeled, yet going forward or backward in time there are multiple trajectories that do not have a large gap between them and are all the same marker. It is best suited for cases when unlabeled trajectories are not many frames away from the labeled marker and the velocity of the marker around the end of the labeled marker and the start of the unlabeled trajectory is fairly constant.

Processing during cleanup

Note that the previous steps for fixing data issues assume that your existing .mcp data is largely of acceptable quality. However, in some circumstances (for example when you are trying to produce better quality data), rather than persisting in trying to fix a problematic .mcp file, you may need to clear the scene and start from the .x2d file, or unlabel all the data first. In this case, do not just open the Processing panel and click Reconstruct or Label or run other Combined Processing operations as this will not fix problems with the underlying data.

Clear existing data

To remove all unlabeled data and clear existing labels and solves, at the top of the Processing panel, select the Reset Scene check box. You can then run Reconstruct, etc. Note that you can't undo the reset.

To remove existing labels from the current file, on the Labeling tab of the Processing panel, select Clear Existing Labels and then run Labeling as required.

To remove occlusion fixing from your data, in the Marker Editing panel, expand the Restore section and select the required option.

Solve during cleanup

During the cleanup operation, each time you finish cleaning up a range, check its solve. To do this:

1. Ensure the range you cleaned up is selected.
2. On the Processing tab on the ribbon, select the arrow on the Solve Solving button.
3. Select Solve Solving Ranges.
   The selected range is solved, enabling you to quickly check that your cleanup has been successful, without having to solve the whole take.
4. Proceed to clean up the next range that contains mislabels, gaps or noisy markers, etc. After you have completed all the cleanup required, finish by solving the entire take. For more information see Solve the data.