## 3 Materials and Methods
### Dataset Creation
#### 3.1.9 Feature Extraction  
After the recognition of the key points mentioned above, the features were extracted as described below. Table 7 below shows the description of the additional computed features of the study. As seen in the table, the calculation of the difference in the Y-Axis of the distinct features in the spine namely (thoracic, thoracolumbar, and lumbar); the distance between nose and left or right shoulder (Trapezius Muscle); Cosine Rule for (Brach) Brachioradialis angle (computed from left/right shoulder, elbow and wrist); Cosine Rule for (TL) Thoraco-Lumbar angle (computed from left/right shoulder, thoracolumbar and lumbar); and the distance between Nose and Thoracic (neck) Distance. These additional features were used in the development of the model for the recognition of proper and improper sitting postures. The significance of these features was also computed and shown in the results.  
Figure 5: The points recognized by Mediapipe and the points recognized by the key point extraction tool.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**SN** & **Feature Name** & **Feature Description** & **Image Representation** \\ \hline \multirow{4}{*}{\(1\)} & & \multicolumn{2}{c}{The difference of three (3) points in the spine—T (Thoracic), TL (Thoracic), and L (Thoraco-Lumbar), and L (Lumbar) in the Y-Axis.} \\  & & \multicolumn{2}{c}{The distance between Left} \\  & & \multicolumn{2}{c}{Shoulder—TML (Trapezius Muscle Left) and N (Nose)} \\  & & \multicolumn{2}{c}{The distance between Right} \\
3 & \multicolumn{2}{c}{nosetorightshoulder} & \multicolumn{2}{c}{Shoulder—TML (Trapezius Muscle Right) and N (Nose)} \\  & & \multicolumn{2}{c}{The distance between Right} \\
4 & \multicolumn{2}{c}{shoulder\_elbow\_dist\_left} & \multicolumn{2}{c}{The distance between elbow} \\  & & \multicolumn{2}{c}{shoulder and elbow.} \\ \hline \multirow{4}{*}{\(5\)} & \multicolumn{2}{c}{elbow\_wrist\_dist\_left} & \multicolumn{2}{c}{The distance between elbow} \\  & & \multicolumn{2}{c}{and wrist} \\ \hline \hline \end{tabular}
\end{table}
Table 7: List of Features.  
\begin{table}
\begin{tabular}{c c c c} \hline
**SN** & **Feature Name** & **Feature Description** & **Image Representation** \\ \hline
7 & shoulder\_mid\_dist\_left & The distance between the shoulder and mid (thoracolumbar) & \\ \hline
8 & mid\_hiP\_dist\_left & The distance between the mid (thoracolumbar) and left or right hip (depending on the camera model) & \\ \hline
9 & hiP\_shoulder\_dist\_left & \\ \hline
10 & SEWangleA & \\ \hline
11 & SEWangleB & \\ \hline
13 & SEWangleC & Cosine Rule for (Brach) & \\ \hline \end{tabular}
\begin{tabular}{c c} \hline
14 & nosetoneck & The distance between Nose and Thoracic Distance \\ \hline \end{tabular}
\end{table}
Table 7: _Cont._For features 11-13, the study applies the cosine rule which follows the procedures below:  
1. First, find the distance between point \(a\) (shoulder left) and point \(b\) (elbow left) using the distance formula below: \[distance=\sqrt{[(x_{1}-x_{2})^{2}+(y_{1}-y_{2})^{2}]}\] (3)
2. Second, find the distance between point \(b\) (elbow left) and point \(c\) (wrist left)
3. Then, find the distance between point \(c\) (wrist left) and point \(a\) (shoulder left)
4. Lastly, apply the cosine rule: \[elbow\ angle=cos^{-1}\left[\frac{(a^{2}+b^{2}-c^{2})}{2 ab}\right]\] (4)