Table 6. The horizontal field of view range.

The field of view	$\mathit{d}$ (m)	$\mathit{l}$ (m)	$\mathit{\theta }$ ( ${}^{\circ }$)	L (m)
Conference room	1.2	1.330	29	3.0
Laboratory	1.5	1.662	29	4.2
Classroom	1.8	1.996	29	4.8