Return the tracked body's centroid at the first frame for scene alignment.
Defaults to "pelvis", falling back to the first available body, but the
tracked body key is configurable since not every 3D view is guaranteed to
include a body named "pelvis".
Return the tracked body's centroid at the first frame for scene alignment.
Defaults to
"pelvis", falling back to the first available body, but the tracked body key is configurable since not every 3D view is guaranteed to include a body named"pelvis".