# A Non-Contact Measurement of Animal Body Size Based on Structured Light
## 4 Discussion  
The parameters calculated from the live rabbit body point cloud are shown in Table 6. Our equipment's average margin of error of measurement is 4.9% compared to that of the manual measurement. The maximum average margin of error is 5.5%, and the minimum average margin of error is 4.3%. The average margin error of measurement obtained with the depth camera is 13.8%, the maximum average margin of error is 18.7%, and the minimum average margin of error is 8.9%. Because the 3D scanner is not instantaneous, it cannot obtain the body point cloud of a live rabbit. The parameters calculated from the fox specimen body point cloud are shown in Table 6. Our equipment's average margin of error of measurement is 2.7%, the maximum \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Animal** & **Parameter** & **Body Length** & **Body Width** & **Tail Length** & **Neck Width** \\ \hline \multirow{8}{*}{Live Rabbit} & manual measurement (cm) & 29.1 & 13.9 & - & - \\  & our equipment (cm) & 27.5 & 13.3 & - & - \\  & error (cm) & 1.6 & 0.6 & - & - \\  & error (\%) & 5.5 & 4.3 & - & - \\  & depth camera (cm) & 31.7 & 11.3 & - & - \\  & error (cm) & 2.6 & 2.6 & - & - \\  & error (\%) & 8.9 & 18.7 & - & - \\ \hline \multirow{8}{*}{Goat Specim} & manual measurement (cm) & 54.2 & 24.9 & - & 9.9 \\  & our equipment (cm) & 54.8 & 24.7 & - & 10.1 \\  & error (cm) & 0.6 & 0.2 & - & 0.2 \\  & error (\%) & 1.1 & 0.8 & - & 2.0 \\  & depth camera (cm) & 62.0 & 24.5 & - & 7.3 \\  & error (cm) & 7.8 & 0.4 & - & 2.6 \\  & error (\%) & 14.4 & 1.6 & - & 26.3 \\  & 3D Scanner (cm) & 62.9 & 25.2 & - & 10.8 \\  & error (cm) & 8.7 & 0.3 & - & 0.9 \\  & error (\%) & 16.1 & 1.2 & - & 9.1 \\ \hline \multirow{8}{*}{Fox Specim} & manual measurement (cm) & 40.1 & 18.1 & 25.0 & - \\  & our equipment (cm) & 38.9 & 17.9 & 24.0 & - \\  & error (cm) & 1.2 & 0.2 & 1.0 & - \\  & error (\%) & 3.0 & 1.1 & 4.0 & - \\  & depth camera (cm) & 43.4 & 15.9 & 26.9 & - \\  & error (cm) & 3.3 & 2.2 & 1.9 & - \\  & error (\%) & 8.2 & 12.1 & 7.6 & - \\  & 3D Scanner (cm) & 39.7 & 16.4 & 25.7 & - \\  & error (cm) & 0.4 & 1.7 & 0.7 & - \\  & error (\%) & 1.0 & 9.4 & 2.8 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Animal body parameters measurement result. average margin of error is 4.0%, and the minimum average margin of error is 1.1%. The average margin of error of measurement obtained with the depth camera is 9.3%, the maximum average margin of error is 12.1%, and the minimum average margin of error is 7.6%. The average margin of error of measurement obtained using the 3D scanner is 4.4%, the maximum average margin of error is 9.4%, and the minimum average margin of error is 1.0%. The parameters calculated from the goat specimen body point cloud are shown in Table 6. Our equipment's average margin of error of measurement is 1.3%, the maximum average margin of error is 2.0%, and the minimum average margin of error is 0.8%. The average margin of error of measurement obtained via the depth camera is 14.1%, the maximum average margin of error is 26.3%, and the minimum average margin of error is 1.61%. The average margin of error of measurement obtained using the 3D scanner is 8.8%, the maximum average margin of error is 16.1%, and the minimum average margin of error is 1.2%. The results of the animal body parameter measurements show that our algorithm successfully alleviates the problem of light scattering on animal fur and has the characteristics of being both instantaneous and robust, which also presents that our equipment has better accuracy compared to the depth camera and 3D scanner on these three animals. The parameter results show that these three types of equipment have high accuracy in determining body width and in determining the measurements for the fox specimen, which is middle-sized. Nevertheless, when the object is transformed into a big-sized animal such as a goat, the drawback of the depth camera and 3D scanner is obvious, while our equipment still has near accuracy.