Versions Compared

Old Version 39

changes.mady.by.user Ayman Habib

Saved on

compared with

New Version Current

changes.mady.by.user Henry Kwong

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

...

Starting with OpenSim 4.0, C3D reading and conversion into OpenSim formats is available. Currently, use of C3D reading is limited to C++ and scripting and we will be working to support direct C3D reading in the GUI in future releases. The easiest way to use OpenSim to read your C3D data is through the Matlab interface. Once you have setup OpenSim use in Matlab, you can read C3D files and write marker and force data to .trc and .mot file formats, easily. 

...

  • read a C3D file containing markers and forces, 
  • get some information about the data (rate, number of markers, and number of forces), 
  • rotate the data, and 

  • then write the markers to a .trc file, and the forces to a .mot file. 

    Expand

...


  • Code Block
    languagejava
    titleExport C3D Matlab
        %% Load OpenSim libs
    import org.opensim.modeling.*
    
    %% Get the path to a C3D file
    [filename, path] = uigetfile('*.c3d');
    c3dpath = fullfile(path,filename);
    
    %% Construct an opensimC3D object with input c3d path
    % Constructor takes full path to c3d file and an integer for forceplate
    % representation in output forces file (0 = electrical center, 1 = COP). 
    c3d = osimC3D(c3dpath,useCenterOfPressureAsMomentsPoint);
    
    %% Get some stats...
    % Get the number of marker trajectories
    nTrajectories = c3d.getNumTrajectories();
    % Get the marker data rate
    rMakers = c3d.getRate_marker();
    % Get the number of forces 
    nForces = c3d.getNumForces();
    % Get the force data rate
    rForces = c3d.getRate_force();
    
    % Get Start and end time
    t0 = c3d.getStartTime();
    tn = c3d.getEndTime();
    
    %% Rotate the data 
    c3d.rotateData('x',-90)
    
    %% Get the c3d in different forms
    % Get OpenSim tables
    markerTable = c3d.getTable_markers();
    forceTable = c3d.getTable_forces();
    % Get as Matlab Structures
    [markerStruct forceStruct] = c3d.getAsStructs();
    
    %% Convert COP (mm to m) and Moments (Nmm to Nm)
    if convertLengthUnits
        c3d.convertMillimeters2Meters();
    end
    
    %% Write the marker and force data to file
    % Define output file names
    basename = strtok(filename,'.');
    markersFilename = strcat(basename,'_markers.trc');
    
    switch useCenterOfPressureAsMomentsPoint
        case 0
            forcesFilename = strcat(basename,'_forces_EC.mot');
        case 1
            forcesFilename = strcat(basename,'_forces_COP.mot');
    end
    
    % Write marker data to trc file.
    c3d.writeTRC(markersFilename);
    
    % Write force data to mot file.
    c3d.writeMOT(forcesFilename);



Reading C3D files through Python and C++

...