Visibility Detection of 3D Objects and Visual K-Nearest Neighbor Query Based on Convex Hull Model

Algorithm 4

Occlude algorithm.

	Input: query point q, candidate set Obj, obstacle set ObsSet;
	Output: True/False;
(1)	BEGIN
(2)	for each obs in ObsSet do
(3)	pToObs←Add(q);
(4)	Concave←BuildConcave (pToObs);
(5)	Ridge←GetRidge(Concave);
(6)	Fac←GetFac(Concave);
(7)	for each ridge in Ridge do
(8)	for each fac in Fac do
(9)	if (ridge.id ! = fac.id) then
(10)	num←IntSegTri (ridge, fac);
(11)	end if
(12)	end for
(13)	end for
(14)	if num.Contains(1) then
(15)	Lis_Obs.Add(ObsSet [ridge.id]);
(16)	end if
(17)	end for
(18)	mulObs←MulJud (q, Obs, Lis_Obs);
(19)	TorF←OneJudVisible(q, Obj, mulObs);
(20)	if TorF = = false
(21)	Return True;
(22)	else
(23)	Return False;
(24)	end if
(25)	END