Dynamic Shadow Elimination with Occluder light suppression

I read one more paper today by the same author. This paper is an advancement of his earlier paper on shadow elimination. The new technique not only eliminates shadows but also removes the light falling on the occluder i.e. the person presenting the slides. This prevents the presenter of the annoying bright light falling on his/her face.

The logic is an advanced version of the one used in simple shadow elimination, explained in my earlier post. The shadow elimination part is same. But now we need to identify which projector's light is being blocked by the presenter and turn off the blocked pixels of that projector. For that the author uses a cyclic check. The author defines a new alpha this time, which is not the same for the corresponding pixels of all the projectors. Its different for each of the projectors.
da_jt = (da_jt)_SE + (da_jt)_LS,
where d stands for the triangle - symbol for delta and a stands for alpha. SE is shadow elimination and LS is light suppression. Delta alpha jt SE is the same old alpha of last post.
(da_jt)_SE = - y(Z_t - Z_o),
where y stands for gamma which was choosen as 0.25 by the author. This shadow elimination alpha is same as before. The new thing is:-
(da_jt)_LS = - B(da²_j(t-N))/(dZ²_(t-N)+e),
where B stands for a beta(a constant) and e for epsilon just added to prevent the denominator from being 0. Now if changing the alpha valus of projector j does not change Z i.e. dZ is 0, then that projector is being occluded and its alpha should go to 0. so when dZ goes 0, denominator becomes very low, so the overall fraction becomes very high and the minus sign leads to subtractiion which makes the alpha near to 0. So thats how Light suppression works. LS has to be done in a cyclic way. Changing alpha LS for the projectors one at a time. For 2 projectors its pretty easy.
Now the author clips da_jt = (da_jt)_SE + (da_jt)_LS, to between 1 and 0 to prevent it from going out of bound.