Algorithm 2 Visible points detection in the cell

1:$map(r,\theta ,\varphi )\leftarrow ConvertCoordinate(X_{str},center)$ 2:$\delta \psi =kta{n}^{-1}(0.01/min\left(r\right))$ 3:for$i=1:\delta \psi :2\pi$do 4: for $j=1:\delta \psi :\pi$ do 5:  $X_{vis}(i,j)\leftarrow f(map,center,i,j,\delta \psi )$ 6: end for 7:end for 8:$X_{vis}=\bigcup X_{vis}(i,j)$