Vessel Trajectory Data Compression Algorithm considering Critical Region Identification

Algorithm 1

Node importance evaluation algorithm.

	Input: Ship latitude and longitude coordinates information Point.
	Output: Node Importance NI.
(1)	N  = Len(Point); NI = list();
(2)	for i = 1 to N − 1 then;
(3)	Calculate the distance D between Point(i − 1) and Point(i+1);
(4)	Calculate the vertical distance of Point(i);
(5)	I = /D
(6)	NI.append(I)
(7)	end for
	return NI