Algorithm 2 ODP algorithm
Input: $trj$(trajectory), $eps$(threshold)
Output: $s\_trj$(simplified trajectory)
1:	function Obstacle_DP$\left(trj,eps,s\_trj\right)$
2:	n $=$ $trj$.size()
3:	$index$, $d_{max}$ = PerpendicularGeoDistance ($trj$, $trj\left[1\right],trj\left[n\right]$)
4:	if $d_{max}>eps$ or LineIntersectPoly $\left(trj\left[1\right],trj\left[n\right]\right)$
5:	result1 $=$ Obstacle_DP $\left(trj\left[1\left],trj\right[1\right]+\mathrm{index}\right)$
6:	result2 $=$ Obstacle_DP $\left(trj\left[1\right]+\mathrm{index},trj\left[n\right]\right)$
7:	s_trj = [result1 result2]
8:	else
9:	s_trj = [$trj\left[1\right]$ $trj\left[n\right]$]
10:	end if
11:	end function