Table 1. Node selection table for eight-directional search method.

Angle α	Retained direction	Removed direction
22.5°–67.5°	1,2,3,7,8	4,5,6
67.5°–112.5°	1,2,3,4,8	5,6,7
112.5°–157.5°	1,2,3,4,5	6,7,8
157.5°–202.5°	2,3,4,5,6	1,7,8
202.5°–247.5°	3,4,5,6,7	1,2,8
247.5°–292.5°	4,5,6,7,8	1,2,3
292.5°–337.5°	1,5,6,7,8	2,3,4
337.5°–360°U0°–22.5°	1,2,6,7,8	3,4,5