Once a motion is loaded, you can associate additional motion data with the loaded motion or add files to color the muscles in your model. Read more about each feature below:
Associate Motion Data
If you load a kinematics file for walking, you can associate the corresponding ground reaction force file or trc file with marker data. You can also use the associate feature to visualize the results of analyses, like a Joint Reactions Analysis or Induced Acceleration Analysis. To associate data from a motion file to a motion that is already loaded into OpenSim:
OpenSim will then load the data file (as in preview motion data) and try to guess based on the contents of the file what objects it contains and display these objects (either markers in trc file or forces extracted from an .mot file). The user can then revisit those guesses to affect the definition of these objects as described below. The user can also save the definition into an ExternalLoads file to be used by other tool
Editing Motion Objects
If you don't see the motion object you created, it might be because it is very small. Try changing the Force display size in the Property Editor and Outputs List. You can also change the color of vector, it's also possible that OpenSim couldn't automatically detect any known objects (markers or forces) in the file because the labels don't follow expected conventions.
The xml configuration file for visualizing motion data is the same as the one used to specify External Loads for Inverse Dynamics and other tools (see How to Use the Inverse Dynamics Tool). Note that the Applied to setting has no effect on visualization, but does affect applied External Loads. The Component selection used for visualization does not affect applied External Loads–all components selected are applied in Inverse Dynamics and other tools.
Coloring Muscles from File
As of OpenSim 3.2, you can also associate a file to dictate muscle coloring. This is useful, for example to visualize the activation results from Static Optimization.
The color data muscle be included in an OpenSim storage (.sto) file. The file should have columns with the muscles names of interest, with values (e.g., activations) ranging from 0 to 1. Muscles with a value of zero will appear blue. Muscles with a value of one or greater will appear red. The file should have an overlapping time range.
As with Associate Motion Data above, you must first load a motion. Then you can right click on the motion, select Color Muscles From File... and choose the storage file with muscle color data. Now, when you playback the motion the muscles will be colored according to your storage file.