Velocity-Preserving Trajectory Compression Based on Retrace Point Detection

Algorithm 2

Trajectory velocity-preserving process.

 Input: trajectory , ratio threshold , inscribed angle threshold , velocity error μ.

 Output: compressed trajectory .

1. i =1, j=3 =Φ.

2. while j<n do

3. Calculate Maximum direction deviation ;

selected pair of anchor point and float point (with the maximum direction deviation);

4.  if

5.   ∪;

6.   i= the last index of set ;

7.   j=i+2;

8.  else:

9.   Calculate velocity error in buffer λ;

10.   if λ>=μ then

11.    ∪;

12.    i=j;

13.    j=i+2;

14.   else:

15.    j=j+1;

16.   end if

17.  end if

18. end while

Return compressed trajectory .