QTMTools

Matlab Toolbox for handling mocap data from QTM. QTMTools supports reading of Matlab exported QTM files.

Mocap data includes:

• 3D trajectory data
• 6DOF rigid body data
• skeleton data

Examples of use.

Read QTM mat file:

mc = mocapdata('myfile.mat')

Indexing:

Retrieve trajectory with label "RightElbow" using the label as index (see labeladmin2 for more info).

relb = mc.Trajectories("RightElbow");

Transform segment from global to parent:

Hips_global = mc.Skeletons(1).Segments('Hips'); % Copy Hips segment (not necessary, but just for clarity)
Spine_local = mc.Skeletons(1).Segments('Spine').global2local(Hips_global);

For more example scripts, see the folder "Examples".

Note: Other types of data, for example analog data, are currently not implemented.

Install

Add the folders including subfolders to the Matlab path, for example using addpath(genpath(...)).

Mocap data classes

mocapdata

Mocap data class. Contains mocap data from QTM files:

• Trajectories (trajectory array)
• RigidBodies (rigidbody array)
• Skeletons (skeleton array)

trajectory

Trajectory data class. Superclasses: labeladmin2 Contains trajectory data:

• Position (vec3d array)
• Residual (double array)
• Type (double array)
• Label (string, from labeladmin2)

rigidbody

Rigid body data class. Superclasses: pose6d, labeladmin2 Contains rigid body data:

• Parent (string)
• Position (vec3d array)
• Rotation (quaternion array)
• Label (string, from labeladmin2)

Methods:

• global2local: transform rigid body to reference coordinate sytem. Overloading pose6d:global2local.

skeleton

Skeleton data class. Superclasses: labeladmin2 Contains skeleton data:

• Segments (segment array)
• Label (string, from labeladmin2)

segment

Segment data class. Super clases: pose6d, labeladmin2 Contains segment data:

• Parent (string)
• Position (vec3d array)
• Rotation (quaternion array)
• Label (string, from labeladmin2)

Methods:

• global2local: transform segment to reference coordinate system. Overloading pose6d:global2local.

Data representation classes

pose6d

Represention of 6DOF data. Properties:

• Position (vec3d array)
• Rotation (quaternion array)

Methods:

• global2local: transform pose6d object to reference coordinate system. Reference system is another pose6d based object of compatible size.
• eulerAngles: retrieve Euler angles based on specified rotation order.
• unitVectors: retrieve unit vectors of local coordinate system.

vec3d

Representation of 3D vector.

Properties: x, y, z

Methods: overloading of relevant basic mathematical operations for vector calculations, e.g., addition, multiplication. Posible to use operators, e.g., p1 + p2. Most methods support binary singleton expansion.

quaternion

Representation of rotation.

Adapted from: Mark Tincknell (2020). quaternion (https://www.mathworks.com/matlabcentral/fileexchange/33341-quaternion), MATLAB Central File Exchange.

Properties: w, x, y, z

Methods: overloading of relevant basic mathematical operations for quaternion calculations, e.g., addition, multiplication. Posible to use operators, e.g., q1 + q2. Most methods support binary singleton expansion.

Helper classes

labeladmin2

Superclass for labeling and subreferencing.

Supports subreferencing using labels, for example: mc.Trajectories('RightElbow') returns the trajectory with label "RightElbow". Label indices can be specified as:

• char array, e.g., 'RightElbow'
• cell array of char, e.g., {'RightElbow', 'LeftElbow'}
• string, e.g., "RightElbow"
• string array, e.g., ["RightElbow", "LeftElbow"]

Properties:

• Label

Methods:

• LabelIndex: retrieve index to object array.
• LabelCheck: check if labels are present.
• LabelList: get list of labels from object array.

Utilities

Helper functions used by the classes.