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The Subjects tab of the Resources pane enables you to prepare and manage the subjects whose motion data you want to capture and analyze in Vicon Nexus.

The Subjects tab contains the following sections:

Subjects toolbar

Create or manage subject nodes for Vicon labeling skeleton templates (.vst files) or Vicon labeling skeletons (.vsk files) using the following buttons in the toolbar at the top of the Subjects Resources pane:

  • Create a blank subject Create a new subject node in the Resources tree. You can subsequently create, attach, or import .vst or .vsk files for the blank node. The node automatically includes the minimum sub nodes for the elements required for a .vst file.
  •  Create a new subject from a labeling skeleton Create a new subject node in the Resources tree based on an existing .vst file. The node automatically includes any sub nodes and data for the elements defined in the selected .vst file.
  •  Load an existing subject Load an existing labeling skeleton (.vsk file) into a subject node in the Resources tree. The node automatically contains sub nodes and data for all elements defined in the selected .vsk file.

Subjects Resources tree

Enable a subject for motion capture and data recording in the tree in the Subjects Resources pane.

Expand ( > ) or collapse ( V ) the following sub-nodes to display or hide a list of subject elements that you can use for selecting, editing, or showing in graph traces:

  • Markers Model markers defined in the .vst or .vsk file as well as trajectories for markers visible in the capture volume or from a loaded .c3d file. The marker text is gray if the marker is not physically present in the capture volume.
  • Segments Segments defined in the .vst or .vsk file.
  • Joints Joints defined in the .vst or .vsk file. The names of the segments that the joint connects are shown in parentheses after the joint name.
  • Model Outputs Components of variables calculated for a kinematic model (such as Angles, Forces, Moments, Powers, or Bones) created by Vicon Plug-in Gait and available in Nexus from a loaded .c3d file.

You can perform commands to manage specific nodes by right-clicking on the node in the Subjects Resources tree and selecting the desired command from the displayed menu.

The color-coded symbols displayed for entries in the Markers and Segments lists correspond to the colors defined for each model marker and joint in the .vst or .vsk file. This provides a helpful visual aid when you are manually labeling a subject. The symbols for entries in the Joints list and the Traces list are not color coded: the same joint symbol is displayed for all joints, and the same model outputs symbol is displayed for all model outputs.

If no markers, segments, or joints have yet been defined for a new subject, the lists may not contain any entries.

Subjects properties

The Properties section at the bottom of the Subjects Resources pane enables you to view or edit properties of the node selected in the Subjects tree. The properties displayed depend upon the subject node, sub node, or element selected in the System Resources tree (marker, segment, joint, or trace). For details on how to specify settings for properties, see Set properties in Vicon Nexus in the Vicon Nexus User Guide.

For more information, see:

Subject node context menu

You can select the following commands from the context menu displayed when you right-click on a subject node:

  • Attach Labeling Skeleton Template In the Choose a Subject file dialog box, navigate to and select the .vst or .vsk file to be attached to this subject node and then click Open. Nexus attaches the specified .vst or .vsk file, closes the dialog box, and updates the subject node with sub nodes and data contained in the specified file.
  • Save Subject Nexus saves the contents of the subject node in a .vsk file in the currently active session of the motion capture database.
  • Save Labeling Skeleton as Template In the Choose a Subject file dialog box, navigate to the folder in which you want to save the Vicon labeling skeleton template, enter the name for the .vst file, and then click Save.

Nexus saves the contents of the subject node in the specified .vst file. It also generates a corresponding marker file with the same base name and a .mkr extension in the same folder. If you subsequently run a BodyBuilder model that requires a marker file, this .mkr file is automatically copied to the relevant session folder.

Save your .vst file in the default Nexus model templates folder (C:\Program Files(x86)\Vicon\Nexus2.#\ModelTemplates) to make it available from the list of available .vst files displayed when you create a new subject node from a template.

  • Revert to Uncalibrated Nexus discards any calibration data in the .vsk file and reverts to the template values within the .vsk.
  • Delete Subject and VSK In the Warning confirmation message, click Yes to proceed.
  • Nexus deletes the subject node from the Subjects Resources pane, unloads the .vsk file from the current session, and unlabels the trajectories associated with that subject

Subject node Properties pane

The Properties section of the Subjects Resources pane enables you to edit the properties of a Vicon labeling skeleton template (.vst file).

You can configure the following settings for a Subject node:

  • Name The name of the selected subject node. This name is used when the Vicon labeling skeleton template is saved in a .vst file or the Vicon labeling skeleton is saved in a .vsk file. You can change this either by overtyping the current name or by clicking the ellipsis (...) to display the Name dialog box in which you can overtype the existing node name with a text string.
  • Color Not currently applicable.
  • Add Parameter Enables you to add a custom parameter (measurement) to the model. In the Add Subject Parameter dialog box, supply a name, specify whether the measurement is required to run the model, specify the units, value and default for your new measurement. 
  • Set All to Default Sets all the selected subject's parameters to their default values.

In the remaining sections, properties vary depending on the labeling skeleton used for the subject selected in the Subjects tree (the following example properties are from a subject based on Plug-in Gait):

General section

  • Bodymass The subject's body mass (in kg).
    Default: As defined in the .vsk or .vst file, or user-specified.
  • Height The subject's height (in mm).
    Default: As defined in the .vsk or .vst file or user-specified
  • InterAsisDistance The distance (in mm) between the subject's left and right anterior superior iliac spine (ASIS).
    Default: As defined in the .vsk or .vst file or user-specified
  • HeadOffset Patient's head offset (in degrees).

Left section and Right section

  • LegLength The length (in mm) of the subject's leg.
    Default: As defined in the .vsk or .vst file or user-specified
  • AsisTrocanterDistance The distance (in mm) between the subject's ASIS and greater trochanter.
    Default: As defined in the .vsk or .vst file or user-specified
  • KneeWidth The width (in mm) of the subject's knee.
    Default: As defined in the .vsk or .vst file or user-specified
  • AnkleWidth The width (in mm) of the subject's ankle.
    Default: As defined in the .vsk or .vst file or user-specified
  • TibialTorsion The torsion (in deg) of the subject's tibia.
    Default: As defined in the .vsk or .vst file or user-specified
  • SoleDelta The distance in millimeters between the thickness of the sole at the toe and at the heel. 
  • ShoulderOffset The vertical distance (in millimeters) from the base of the acromion marker to the shoulder joint center.
  • ElbowWidth The width (in millimeters) of the elbow along flexion axis. 
  • WristWidth The anterior/posterior width (in millimeters) of the wrist.
  • HandThickness The anterior/posterior width (in millimeters) of the hand.

For more details on these measurements, see Take subject measurements for Plug-in Gait in the Vicon Nexus User Guide.

Markers context menus

You can select the following command from the context menu displayed when you right-click on the Markers node:

  • Reorder Displays the Reorder Markers dialog box, where you can change the order in which the markers are displayed.

You can select the following command from the context menu displayed when you right-click on a sub node for a specific marker:

  • Detach Marker The marker is detached from the subject and is no longer displayed in the list of markers on the Subjects tab (and is removed from the VSK) or the Manual Labeling list in the Label/Edit Tools pane.

Markers properties

You can configure the following settings in the Properties section for the markers:

  • Name The name of the Vicon marker. You can rename a marker by overtyping it.
    Default: As defined in .vsk or .vst file or as specified in the Labeling Template Builder.
  • Color The color in which to display the Vicon marker in a 3D Perspective view pane. You can assign either a specific color or the associated context color.
    Default: As defined in .vsk or .vst file or as specified in the Labeling Template Builder.
  • Radius The size of the Vicon marker attached to subject during trial capture. This setting also dictates the size of the marker displayed in the 3D Perspective view pane. You can change the radius by either overtyping the current value or dragging the slider bar left to decrease the value or right to increase it.
    Default: As defined in .vsk or .vst file or as specified in the Labeling Template Builder
  • Status The requirement for the marker's inclusion in a .vst file for static trials (used for calibration) and/or the .vsk file calibrated from the .vst file for dynamic trials (used for analysis):
  • Required: Marker must be present for both static and dynamic trials.
  • Optional: Marker can optionally be left off. If the marker is not present for the calibration, the autolabeler will not look for it in the dynamic trials. If the marker is present in the static trial, it will also form part of the dynamic marker set and will be used to aid tracking and to provide redundancy.
  • Calibration Only: Marker must be present for static trials to align coordinate systems, but it must be removed for dynamic trials.
    Default: Required

Segments context menu

You can select the following commands from the context menu displayed when you right-click on a sub node for a specific segment:

  • Pick as Kinematic Fill Source Enables you to copy the kinematics from the selected segment to fill a gap.
    The suggested fill is displayed in purple in the 3D Perspective window. You can also view the suggested fill options as colored dotted lines in the Graph view.
  • Delete Segment Deletes the selected segment.

Segments properties

You can configure the following settings in the Properties section for the segments:

  • Name The name of the skeleton segment.
    Default: As defined in .vsk or .vst file or as specified in the Labeling Template Builder
  • Color The color in which to display the skeleton segment in a 3D Perspective view pane. You can assign either a specific color or the associated context color.
    Default: As defined in .vsk or .vst file or as specified in the Labeling Template Builder  

Joints context menu

You can select the following command from the context menu displayed when you right-click on a sub node for a specific Joint:

  • Unlink Joint Unlinks the selected segments.

Joints properties

  • Name The names of the segments connected by the joint.Default: As defined in .vsk or .vst file or as specified in the Labeling Template Builder.
  • Output Format The joint angle output format (if appropriate):
    • XYZ Euler Angles
    • ZYX Euler Angles
    • XZY Euler Angles
    • ZX Euler Angles
    • YXZ Euler Angles
    • ZXY Euler Angles
    • Helical Axis
    Default: Helical Axis

Model Output properties

  • Name The names of the model outputs in a loaded .c3d file.
    Default: As defined in the .c3d file

Model Outputs context menu

Model outputs depend upon the modeling that is performed, but can include some or all of the following:

  • Angles
  • Forces
  • Moments
  • Powers
  • Scalars
  • Bones

You can delete a single model output, groups of model outputs or all the outputs under a single output sub-node by right-clicking on the relevant node(s) in the Subjects Resources tree and then clicking Delete. (You can also delete model outputs using the Delete Model Outputs pipeline operation, available in the Data Processing operations on the Pipeline Tools pane.)

Element color properties

In the Color property for Markers and Segments, you can specify the default color for these subject elements using one of the following methods:

  • Assign a specific color using the color map.
  • Click the current color in the entry field to display the Select Color dialog box.
  • In the Basic colors area, click the square for the desired color, or in the Custom colors areas define a new color.
  • Specify the default color of its associated context (if any) using the Context Color macro.
  • Click the Color property context menu button and select Macro. Context Color is displayed in the entry field. A marker inherits its context from the segment to which it is attached. A segment's context is derived from its name, for example "LeftFemur" has a left context. To turn off the context color macro, clear Macro in the Color property context menu.
ContextDefault Color
GeneralOrange
LeftRed
RightGreen