Fire Detection Algorithms Using Multimodal ... - Bilkent University

CHAPTER 2. FLAME DETECTION IN VISIBLE RANGE VIDEO 27Both the 1-D temporal wavelet analysis described in Subsection 2.2.3 andthe 2-D spatial wavelet analysis are computationally efficient schemes because amultiplierless filter bank is used for both 1-D and 2-D wavelet transform computation[34], [45]. Lowpass and highpass filters have weights { 1, 1, 1 −1} and { , 1, −1},4 2 4 4 2 4respectively. They can be implemented by register shifts without performing anymultiplications.The wavelet analysis based steps of the algorithm are very important in fireand flame detection because they distinguish ordinary motion in the video frommotion due to turbulent flames and fire.2.3 Decision FusionIn this section, we describe a voting based decision fusion strategy. However,other data fusion methods can be also used to combine the decision of four stagesof the flame and fire detection algorithm.Voting schemes include unanimity voting, majority voting, and m-out-of-nvoting. In m-out-of-n voting scheme, an output choice is accepted if at leastm votes agree with the decisions of n sensors [60]. We use a variant of m-outof-nvoting, the so-called T -out-of-v voting in which the output is accepted ifH = ∑ i w iv i > T where the w i ’s are user-defined weights, the v i ’s are decisionsof the four stages of the algorithm, and T is a user-defined threshold. Decisionparameter v i can take binary values 0 and 1, corresponding to normal case andthe existence of fire, respectively. The decision parameter v 1 is 1 if the pixel isa moving pixel, and 0 if it is stationary. The decision parameter v 2 is taken as1 if the pixel is fire-colored, and 0 otherwise. The decision parameter v 3 is 1 ifthe probability value of flame model is larger than that of non-flame model. Thedecision parameter v 4 is defined in Equation (2.12).In uncontrolled fire, it is expected that the fire region should have a nonconvexboundary. To gain a further robustness to false alarms, another stepchecking the convexity of the fire region is also added to the proposed algorithm.