Table 6.

Signals constructed from key-points and used for feature extraction for each of the five bradykinesia items.

MDS-UPDRS item	Time-series signal	Formula
Finger Tapping	Euclidean distance between the thumb-tip key-point and the index finger tip key-point, measured in units of estimated-standing height.	$\frac{\overrightarrow{∣\left({\mathbf{P}}_{h\left(4\right)}{\mathbf{P}}_{h\left(8\right)}\right)∣}}{\mathrm{H}}$
Hand Movement	The area of the convex hull (ACH) of the four finger tips key-points and the palm key-point, measured in units of estimated-standing-height squared (H2).	$\frac{\mathrm{ACH}\left({\mathbf{P}}_{h\left(i\right)}:i\in \left(0,8,12,16,20\right)\right)}{{\mathrm{H}}^2}$
Pronation-Supination	The angular velocity of the vector from the thumb-tip key-point to the little-finger-tip key-points, measured in degrees per frame.	$\angle \left({\mathbf{V}}_{h\left(4,20\right)}^{t-1},{\mathbf{V}}_{h\left(4,20\right)}^t\right)$
Toe Tapping	The vertical distance between the small toe and the neck, measured in units of estimated-standing height.	$\frac{\left({\mathbf{y}}_{b\left(i\right)}-{\mathbf{y}}_{b\left(1\right)}\right)}{\mathrm{H}},i=\left\{\begin{array}{cc}20\hfill & \mathrm{left}\hfill \\ 23\hfill & \mathrm{right}\hfill \end{array}\right)$
Leg Agility	The Euclidean distance between the knee key-point and the neck key-point, measured in units of estimated-standing height.	$\frac{\overrightarrow{\mid {\mathbf{P}}_{b\left(i\right)}{\mathbf{P}}_{b\left(1\right)}\mid }}{\mathrm{H}},i=\left\{\begin{array}{cc}13\hfill & \mathrm{left}\hfill \\ 10\hfill & \mathrm{right}\hfill \end{array}\right)$