Loading Optitrack Motions onto Character Studio Avatars

Optitrack Arena Software enables you to export captured and trajectorized animation files in the BVH format.
Such files can be loaded onto character studio bipeds for animation.
However, the animations need to be converted to match the biped skeleton first. This can be achieved as follows:
open biped character

Choose the biped to activate the character studio panel. This can be done by pressning the "H" key and selecting the first element in the biped hierarchy:
choose the biped to activate character studio panel

Choose figure mode to save the biped structure of the avatar:
Choose Figure Mode

Save the skeletal structure of your Avatar in for example AMan0004-CS.fig file.
Save the structure of the figure

Remove the character by selecting all and pressing delete.

Create a new Biped
Create New Biped

Load BVH file onto biped

Accept Mocap Dialog by pressing OK.
Accept Mocap Dialog

Test the motion on the  biped
Test the motion on the biped

Go to Figure Mode

Load the structure of the original Avatar
Once you have pressed Load Max will adapt the existing animation to the structure of the original avatar that is contained in the .fig file.

Now we can leave the figure mode and save the biped and the animation that was loaded onto it.
Original Biped with the Optitrack motion applied

Save the biped with the whole motion sequence:
Save Biped with Motion

Remove the bipead and create a new scene.
Load the original Avatar that we used to save the .fig file for the skeletal structure.

Go into the character studio panel and load the prepared .bip file.
Load preprocessed motion onto Avatar

Thats it. Now the motion can be adapted by using layers or by segmenting it into pieces for looping and blending.