Algorithm 3: Pseudocode for the practical experiment.

(I) Simultaneously capture the images $I_i\left(i=1,2,\dots ,n\right)$ and record the corresponding inclination data $\left({\theta }_i,{\varphi }_i\right),i=1,2,\dots ,n$. (II) Detect plumb lines in the captured image $I_i\left(i=1,2,\dots ,N,N=\frac{2}{3}n\right)$ using the Hough line detection method, and extract the endpoints of each line $\left(x_i,y_i\right),\left(i=1,2,\dots ,N\right)$. (III) Calculate the inclinometer assembly error $R_{ic}$ using the $N$ images and corresponding information. (IV) Horizontally correct the $n-N$ retained images using the calibrated matrix $R_{ic}$. (V) Detect the endpoints of the horizontal corrected images and calculate the angle with the $x$-axis on the same line.